DATAMONGO-2246 - Release version 2.1.7 (Lovelace SR7).

Ensure to have to DbRefResolver operate within the session while reusing the MappingContext.

Original Pull Request: #734

.travis.yml

@@ -13,12 +13,12 @@ before_install:
   - |-
     downloads/mongodb-linux-x86_64-ubuntu1604-${MONGO_VERSION}/bin/mongo --eval "rs.initiate({_id: 'rs0', members:[{_id: 0, host: '127.0.0.1:27017'}]});"
     sleep 15
-    
+
 env:
   matrix:
     - PROFILE=ci
   global:
-    - MONGO_VERSION=3.7.9
+    - MONGO_VERSION=4.0.0
 
 addons:
   apt:

README.md

@@ -83,7 +83,7 @@ You can have Spring automatically create a proxy for the interface by using the
 class ApplicationConfig extends AbstractMongoConfiguration {
 
   @Override
-  public Mongo mongo() throws Exception {
+  public MongoClient mongoClient() throws Exception {
     return new MongoClient();
   }
 
@@ -138,6 +138,42 @@ public class MyService {
 }
 ```
 
+### MongoDB 4.0 Transactions
+
+As of version 4 MongoDB supports [Transactions](https://www.mongodb.com/transactions). Transactions are built on top of
+ `ClientSessions` and therefore require an active session.
+
+`MongoTransactionManager` is the gateway to the well known Spring transaction support. It allows applications to use 
+[managed transaction features of Spring](http://docs.spring.io/spring/docs/current/spring-framework-reference/html/transaction.html).
+The `MongoTransactionManager` binds a `ClientSession` to the thread. `MongoTemplate` automatically detects those and operates on them accordingly.
+
+```java
+@Configuration
+static class Config extends AbstractMongoConfiguration {
+
+	@Bean
+	MongoTransactionManager transactionManager(MongoDbFactory dbFactory) {
+		return new MongoTransactionManager(dbFactory);
+	}
+
+	// ...
+}
+
+@Component
+public class StateService {
+
+	@Transactional
+	void someBusinessFunction(Step step) {
+
+		template.insert(step);
+
+		process(step);
+
+		template.update(Step.class).apply(Update.set("state", // ...
+	};
+});
+```
+
 ## Contributing to Spring Data
 
 Here are some ways for you to get involved in the community:

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>2.0.14.RELEASE</version>
+	<version>2.1.7.RELEASE</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data MongoDB</name>
@@ -15,7 +15,7 @@
 	<parent>
 		<groupId>org.springframework.data.build</groupId>
 		<artifactId>spring-data-parent</artifactId>
-		<version>2.0.14.RELEASE</version>
+		<version>2.1.7.RELEASE</version>
 	</parent>
 
 	<modules>
@@ -27,9 +27,9 @@
 	<properties>
 		<project.type>multi</project.type>
 		<dist.id>spring-data-mongodb</dist.id>
-		<springdata.commons>2.0.14.RELEASE</springdata.commons>
-		<mongo>3.5.0</mongo>
-		<mongo.reactivestreams>1.6.0</mongo.reactivestreams>
+		<springdata.commons>2.1.7.RELEASE</springdata.commons>
+		<mongo>3.8.2</mongo>
+		<mongo.reactivestreams>1.9.2</mongo.reactivestreams>
 		<jmh.version>1.19</jmh.version>
 	</properties>
 
@@ -179,6 +179,11 @@
 			<id>spring-plugins-release</id>
 			<url>https://repo.spring.io/plugins-release</url>
 		</pluginRepository>
+		<pluginRepository>
+			<id>spring-libs-milestone</id>
+			<url>https://repo.spring.io/libs-milestone</url>
+		</pluginRepository>
+
 	</pluginRepositories>
 
 </project>

spring-data-mongodb-benchmarks/pom.xml

@@ -7,7 +7,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.14.RELEASE</version>
+		<version>2.1.7.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb-cross-store/pom.xml

@@ -6,7 +6,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.14.RELEASE</version>
+		<version>2.1.7.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -50,7 +50,7 @@
 		<dependency>
 			<groupId>org.springframework.data</groupId>
 			<artifactId>spring-data-mongodb</artifactId>
-			<version>2.0.14.RELEASE</version>
+			<version>2.1.7.RELEASE</version>
 		</dependency>
 
 		<!-- reactive -->

spring-data-mongodb-cross-store/src/main/java/org/springframework/data/mongodb/crossstore/MongoChangeSetPersister.java

@@ -204,7 +204,7 @@ public class MongoChangeSetPersister implements ChangeSetPersister<Object> {
 
 	/**
 	 * Returns the collection the given entity type shall be persisted to.
-	 * 
+	 *
 	 * @param entityClass must not be {@literal null}.
 	 * @return
 	 */

spring-data-mongodb-cross-store/src/test/java/org/springframework/data/mongodb/crossstore/CrossStoreMongoTests.java

@@ -39,7 +39,7 @@ import org.springframework.transaction.support.TransactionTemplate;
 
 /**
  * Integration tests for MongoDB cross-store persistence (mainly {@link MongoChangeSetPersister}).
- * 
+ *
  * @author Thomas Risberg
  * @author Oliver Gierke
  */

spring-data-mongodb-distribution/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.14.RELEASE</version>
+		<version>2.1.7.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 

spring-data-mongodb/pom.xml

@@ -11,7 +11,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>2.0.14.RELEASE</version>
+		<version>2.1.7.RELEASE</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
@@ -20,6 +20,7 @@
 		<equalsverifier>1.7.8</equalsverifier>
 		<java-module-name>spring.data.mongodb</java-module-name>
 		<project.root>${basedir}/..</project.root>
+		<multithreadedtc>1.01</multithreadedtc>
 	</properties>
 
 	<dependencies>
@@ -245,6 +246,20 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+			<groupId>edu.umd.cs.mtc</groupId>
+			<artifactId>multithreadedtc</artifactId>
+			<version>${multithreadedtc}</version>
+			<scope>test</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>javax.transaction</groupId>
+			<artifactId>jta</artifactId>
+			<version>1.1</version>
+			<scope>test</scope>
+		</dependency>
+
 		<!-- Kotlin extension -->
 		<dependency>
 			<groupId>org.jetbrains.kotlin</groupId>
@@ -264,25 +279,12 @@
 			<version>${kotlin}</version>
 			<scope>test</scope>
 		</dependency>
+
 		<dependency>
-			<groupId>com.nhaarman</groupId>
-			<artifactId>mockito-kotlin</artifactId>
-			<version>1.5.0</version>
+			<groupId>io.mockk</groupId>
+			<artifactId>mockk</artifactId>
+			<version>${mockk}</version>
 			<scope>test</scope>
-			<exclusions>
-				<exclusion>
-					<groupId>org.jetbrains.kotlin</groupId>
-					<artifactId>kotlin-stdlib</artifactId>
-				</exclusion>
-				<exclusion>
-					<groupId>org.jetbrains.kotlin</groupId>
-					<artifactId>kotlin-reflect</artifactId>
-				</exclusion>
-				<exclusion>
-					<groupId>org.mockito</groupId>
-					<artifactId>mockito-core</artifactId>
-				</exclusion>
-			</exclusions>
 		</dependency>
 
 	</dependencies>

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/BulkOperationException.java

@@ -25,7 +25,7 @@ import com.mongodb.BulkWriteResult;
 
 /**
  * Is thrown when errors occur during bulk operations.
- * 
+ *
  * @author Tobias Trelle
  * @author Oliver Gierke
  * @since 1.9
@@ -39,7 +39,7 @@ public class BulkOperationException extends DataAccessException {
 
 	/**
 	 * Creates a new {@link BulkOperationException} with the given message and source {@link BulkWriteException}.
-	 * 
+	 *
 	 * @param message must not be {@literal null}.
 	 * @param source must not be {@literal null}.
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/ClientSessionException.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import org.springframework.dao.NonTransientDataAccessException;
+import org.springframework.lang.Nullable;
+
+/**
+ * {@link NonTransientDataAccessException} specific to MongoDB {@link com.mongodb.session.ClientSession} related data
+ * access failures such as reading data using an already closed session.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public class ClientSessionException extends NonTransientDataAccessException {
+
+	/**
+	 * Constructor for {@link ClientSessionException}.
+	 *
+	 * @param msg the detail message. Must not be {@literal null}.
+	 */
+	public ClientSessionException(String msg) {
+		super(msg);
+	}
+
+	/**
+	 * Constructor for {@link ClientSessionException}.
+	 *
+	 * @param msg the detail message. Can be {@literal null}.
+	 * @param cause the root cause. Can be {@literal null}.
+	 */
+	public ClientSessionException(@Nullable String msg, @Nullable Throwable cause) {
+		super(msg, cause);
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/CodecRegistryProvider.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import java.util.Optional;
+
+import org.bson.codecs.Codec;
+import org.bson.codecs.configuration.CodecConfigurationException;
+import org.bson.codecs.configuration.CodecRegistry;
+import org.springframework.util.Assert;
+
+/**
+ * Provider interface to obtain {@link CodecRegistry} from the underlying MongoDB Java driver.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+@FunctionalInterface
+public interface CodecRegistryProvider {
+
+	/**
+	 * Get the underlying {@link CodecRegistry} used by the MongoDB Java driver.
+	 *
+	 * @return never {@literal null}.
+	 * @throws IllegalStateException if {@link CodecRegistry} cannot be obtained.
+	 */
+	CodecRegistry getCodecRegistry();
+
+	/**
+	 * Checks if a {@link Codec} is registered for a given type.
+	 *
+	 * @param type must not be {@literal null}.
+	 * @return true if {@link #getCodecRegistry()} holds a {@link Codec} for given type.
+	 * @throws IllegalStateException if {@link CodecRegistry} cannot be obtained.
+	 */
+	default boolean hasCodecFor(Class<?> type) {
+		return getCodecFor(type).isPresent();
+	}
+
+	/**
+	 * Get the {@link Codec} registered for the given {@literal type} or an {@link Optional#empty() empty Optional}
+	 * instead.
+	 *
+	 * @param type must not be {@literal null}.
+	 * @param <T>
+	 * @return never {@literal null}.
+	 * @throws IllegalArgumentException if {@literal type} is {@literal null}.
+	 */
+	default <T> Optional<Codec<T>> getCodecFor(Class<T> type) {
+
+		Assert.notNull(type, "Type must not be null!");
+
+		try {
+			return Optional.of(getCodecRegistry().get(type));
+		} catch (CodecConfigurationException e) {
+			// ignore
+		}
+		return Optional.empty();
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoCollectionUtils.java

@@ -23,7 +23,7 @@ import org.springframework.util.StringUtils;
  * <p/>
  * <p/>
  * Mainly intended for internal use within the framework.
- * 
+ *
  * @author Thomas Risberg
  * @since 1.0
  */
@@ -38,7 +38,7 @@ public abstract class MongoCollectionUtils {
 
 	/**
 	 * Obtains the collection name to use for the provided class
-	 * 
+	 *
 	 * @param entityClass The class to determine the preferred collection name for
 	 * @return The preferred collection name
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoDatabaseUtils.java

@@ -0,0 +1,240 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import org.springframework.lang.Nullable;
+import org.springframework.transaction.support.ResourceHolderSynchronization;
+import org.springframework.transaction.support.TransactionSynchronization;
+import org.springframework.transaction.support.TransactionSynchronizationManager;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.client.ClientSession;
+import com.mongodb.client.MongoDatabase;
+
+/**
+ * Helper class for managing a {@link MongoDatabase} instances via {@link MongoDbFactory}. Used for obtaining
+ * {@link ClientSession session bound} resources, such as {@link MongoDatabase} and
+ * {@link com.mongodb.client.MongoCollection} suitable for transactional usage.
+ * <p />
+ * <strong>Note:</strong> Intended for internal usage only.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @currentRead Shadow's Edge - Brent Weeks
+ * @since 2.1
+ */
+public class MongoDatabaseUtils {
+
+	/**
+	 * Obtain the default {@link MongoDatabase database} form the given {@link MongoDbFactory factory} using
+	 * {@link SessionSynchronization#ON_ACTUAL_TRANSACTION native session synchronization}.
+	 * <p />
+	 * Registers a {@link MongoSessionSynchronization MongoDB specific transaction synchronization} within the current
+	 * {@link Thread} if {@link TransactionSynchronizationManager#isSynchronizationActive() synchronization is active}.
+	 *
+	 * @param factory the {@link MongoDbFactory} to get the {@link MongoDatabase} from.
+	 * @return the {@link MongoDatabase} that is potentially associated with a transactional {@link ClientSession}.
+	 */
+	public static MongoDatabase getDatabase(MongoDbFactory factory) {
+		return doGetMongoDatabase(null, factory, SessionSynchronization.ON_ACTUAL_TRANSACTION);
+	}
+
+	/**
+	 * Obtain the default {@link MongoDatabase database} form the given {@link MongoDbFactory factory}.
+	 * <p />
+	 * Registers a {@link MongoSessionSynchronization MongoDB specific transaction synchronization} within the current
+	 * {@link Thread} if {@link TransactionSynchronizationManager#isSynchronizationActive() synchronization is active}.
+	 *
+	 * @param factory the {@link MongoDbFactory} to get the {@link MongoDatabase} from.
+	 * @param sessionSynchronization the synchronization to use. Must not be {@literal null}.
+	 * @return the {@link MongoDatabase} that is potentially associated with a transactional {@link ClientSession}.
+	 */
+	public static MongoDatabase getDatabase(MongoDbFactory factory, SessionSynchronization sessionSynchronization) {
+		return doGetMongoDatabase(null, factory, sessionSynchronization);
+	}
+
+	/**
+	 * Obtain the {@link MongoDatabase database} with given name form the given {@link MongoDbFactory factory} using
+	 * {@link SessionSynchronization#ON_ACTUAL_TRANSACTION native session synchronization}.
+	 * <p />
+	 * Registers a {@link MongoSessionSynchronization MongoDB specific transaction synchronization} within the current
+	 * {@link Thread} if {@link TransactionSynchronizationManager#isSynchronizationActive() synchronization is active}.
+	 *
+	 * @param dbName the name of the {@link MongoDatabase} to get.
+	 * @param factory the {@link MongoDbFactory} to get the {@link MongoDatabase} from.
+	 * @return the {@link MongoDatabase} that is potentially associated with a transactional {@link ClientSession}.
+	 */
+	public static MongoDatabase getDatabase(String dbName, MongoDbFactory factory) {
+		return doGetMongoDatabase(dbName, factory, SessionSynchronization.ON_ACTUAL_TRANSACTION);
+	}
+
+	/**
+	 * Obtain the {@link MongoDatabase database} with given name form the given {@link MongoDbFactory factory}.
+	 * <p />
+	 * Registers a {@link MongoSessionSynchronization MongoDB specific transaction synchronization} within the current
+	 * {@link Thread} if {@link TransactionSynchronizationManager#isSynchronizationActive() synchronization is active}.
+	 * 
+	 * @param dbName the name of the {@link MongoDatabase} to get.
+	 * @param factory the {@link MongoDbFactory} to get the {@link MongoDatabase} from.
+	 * @param sessionSynchronization the synchronization to use. Must not be {@literal null}.
+	 * @return the {@link MongoDatabase} that is potentially associated with a transactional {@link ClientSession}.
+	 */
+	public static MongoDatabase getDatabase(String dbName, MongoDbFactory factory,
+			SessionSynchronization sessionSynchronization) {
+		return doGetMongoDatabase(dbName, factory, sessionSynchronization);
+	}
+
+	private static MongoDatabase doGetMongoDatabase(@Nullable String dbName, MongoDbFactory factory,
+			SessionSynchronization sessionSynchronization) {
+
+		Assert.notNull(factory, "Factory must not be null!");
+
+		if (!TransactionSynchronizationManager.isSynchronizationActive()) {
+			return StringUtils.hasText(dbName) ? factory.getDb(dbName) : factory.getDb();
+		}
+
+		ClientSession session = doGetSession(factory, sessionSynchronization);
+
+		if (session == null) {
+			return StringUtils.hasText(dbName) ? factory.getDb(dbName) : factory.getDb();
+		}
+
+		MongoDbFactory factoryToUse = factory.withSession(session);
+		return StringUtils.hasText(dbName) ? factoryToUse.getDb(dbName) : factoryToUse.getDb();
+	}
+
+	/**
+	 * Check if the {@link MongoDbFactory} is actually bound to a {@link ClientSession} that has an active transaction, or
+	 * if a {@link TransactionSynchronization} has been registered for the {@link MongoDbFactory resource} and if the
+	 * associated {@link ClientSession} has an {@link ClientSession#hasActiveTransaction() active transaction}.
+	 *
+	 * @param dbFactory the resource to check transactions for. Must not be {@literal null}.
+	 * @return {@literal true} if the factory has an ongoing transaction.
+	 * @since 2.1.3
+	 */
+	public static boolean isTransactionActive(MongoDbFactory dbFactory) {
+
+		if (dbFactory.isTransactionActive()) {
+			return true;
+		}
+
+		MongoResourceHolder resourceHolder = (MongoResourceHolder) TransactionSynchronizationManager.getResource(dbFactory);
+		return resourceHolder != null && resourceHolder.hasActiveTransaction();
+	}
+
+	@Nullable
+	private static ClientSession doGetSession(MongoDbFactory dbFactory, SessionSynchronization sessionSynchronization) {
+
+		MongoResourceHolder resourceHolder = (MongoResourceHolder) TransactionSynchronizationManager.getResource(dbFactory);
+
+		// check for native MongoDB transaction
+		if (resourceHolder != null && (resourceHolder.hasSession() || resourceHolder.isSynchronizedWithTransaction())) {
+
+			if (!resourceHolder.hasSession()) {
+				resourceHolder.setSession(createClientSession(dbFactory));
+			}
+
+			return resourceHolder.getSession();
+		}
+
+		if (SessionSynchronization.ON_ACTUAL_TRANSACTION.equals(sessionSynchronization)) {
+			return null;
+		}
+
+		// init a non native MongoDB transaction by registering a MongoSessionSynchronization
+
+		resourceHolder = new MongoResourceHolder(createClientSession(dbFactory), dbFactory);
+		resourceHolder.getRequiredSession().startTransaction();
+
+		TransactionSynchronizationManager
+				.registerSynchronization(new MongoSessionSynchronization(resourceHolder, dbFactory));
+		resourceHolder.setSynchronizedWithTransaction(true);
+		TransactionSynchronizationManager.bindResource(dbFactory, resourceHolder);
+
+		return resourceHolder.getSession();
+	}
+
+	private static ClientSession createClientSession(MongoDbFactory dbFactory) {
+		return dbFactory.getSession(ClientSessionOptions.builder().causallyConsistent(true).build());
+	}
+
+	/**
+	 * MongoDB specific {@link ResourceHolderSynchronization} for resource cleanup at the end of a transaction when
+	 * participating in a non-native MongoDB transaction, such as a Jta or JDBC transaction.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	private static class MongoSessionSynchronization extends ResourceHolderSynchronization<MongoResourceHolder, Object> {
+
+		private final MongoResourceHolder resourceHolder;
+
+		MongoSessionSynchronization(MongoResourceHolder resourceHolder, MongoDbFactory dbFactory) {
+
+			super(resourceHolder, dbFactory);
+			this.resourceHolder = resourceHolder;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.transaction.support.ResourceHolderSynchronization#shouldReleaseBeforeCompletion()
+		 */
+		@Override
+		protected boolean shouldReleaseBeforeCompletion() {
+			return false;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.transaction.support.ResourceHolderSynchronization#processResourceAfterCommit(java.lang.Object)
+		 */
+		@Override
+		protected void processResourceAfterCommit(MongoResourceHolder resourceHolder) {
+
+			if (resourceHolder.hasActiveTransaction()) {
+				resourceHolder.getRequiredSession().commitTransaction();
+			}
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.transaction.support.ResourceHolderSynchronization#afterCompletion(int)
+		 */
+		@Override
+		public void afterCompletion(int status) {
+
+			if (status == TransactionSynchronization.STATUS_ROLLED_BACK && this.resourceHolder.hasActiveTransaction()) {
+				resourceHolder.getRequiredSession().abortTransaction();
+			}
+
+			super.afterCompletion(status);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.transaction.support.ResourceHolderSynchronization#releaseResource(java.lang.Object, java.lang.Object)
+		 */
+		@Override
+		protected void releaseResource(MongoResourceHolder resourceHolder, Object resourceKey) {
+
+			if (resourceHolder.hasActiveSession()) {
+				resourceHolder.getRequiredSession().close();
+			}
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoDbFactory.java

@@ -15,11 +15,14 @@
  */
 package org.springframework.data.mongodb;
 
+import org.bson.codecs.configuration.CodecRegistry;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.core.MongoExceptionTranslator;
 
+import com.mongodb.ClientSessionOptions;
 import com.mongodb.DB;
+import com.mongodb.client.ClientSession;
 import com.mongodb.client.MongoDatabase;
 
 /**
@@ -27,8 +30,9 @@ import com.mongodb.client.MongoDatabase;
  *
  * @author Mark Pollack
  * @author Thomas Darimont
+ * @author Christoph Strobl
  */
-public interface MongoDbFactory {
+public interface MongoDbFactory extends CodecRegistryProvider, MongoSessionProvider {
 
 	/**
 	 * Creates a default {@link MongoDatabase} instance.
@@ -54,5 +58,65 @@ public interface MongoDbFactory {
 	 */
 	PersistenceExceptionTranslator getExceptionTranslator();
 
+	/**
+	 * Get the legacy database entry point. Please consider {@link #getDb()} instead.
+	 *
+	 * @return
+	 * @deprecated since 2.1, use {@link #getDb()}. This method will be removed with a future version as it works only
+	 *             with the legacy MongoDB driver.
+	 */
+	@Deprecated
 	DB getLegacyDb();
+
+	/**
+	 * Get the underlying {@link CodecRegistry} used by the MongoDB Java driver.
+	 *
+	 * @return never {@literal null}.
+	 */
+	@Override
+	default CodecRegistry getCodecRegistry() {
+		return getDb().getCodecRegistry();
+	}
+
+	/**
+	 * Obtain a {@link ClientSession} for given ClientSessionOptions.
+	 *
+	 * @param options must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	ClientSession getSession(ClientSessionOptions options);
+
+	/**
+	 * Obtain a {@link ClientSession} bound instance of {@link MongoDbFactory} returning {@link MongoDatabase} instances
+	 * that are aware and bound to a new session with given {@link ClientSessionOptions options}.
+	 *
+	 * @param options must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default MongoDbFactory withSession(ClientSessionOptions options) {
+		return withSession(getSession(options));
+	}
+
+	/**
+	 * Obtain a {@link ClientSession} bound instance of {@link MongoDbFactory} returning {@link MongoDatabase} instances
+	 * that are aware and bound to the given session.
+	 *
+	 * @param session must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	MongoDbFactory withSession(ClientSession session);
+
+	/**
+	 * Returns if the given {@link MongoDbFactory} is bound to a {@link ClientSession} that has an
+	 * {@link ClientSession#hasActiveTransaction() active transaction}.
+	 *
+	 * @return {@literal true} if there's an active transaction, {@literal false} otherwise.
+	 * @since 2.1.3
+	 */
+	default boolean isTransactionActive() {
+		return false;
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoResourceHolder.java

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import org.springframework.lang.Nullable;
+import org.springframework.transaction.TransactionDefinition;
+import org.springframework.transaction.support.ResourceHolderSupport;
+
+import com.mongodb.client.ClientSession;
+
+/**
+ * MongoDB specific {@link ResourceHolderSupport resource holder}, wrapping a {@link ClientSession}.
+ * {@link MongoTransactionManager} binds instances of this class to the thread.
+ * <p />
+ * <strong>Note:</strong> Intended for internal usage only.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ * @see MongoTransactionManager
+ * @see org.springframework.data.mongodb.core.MongoTemplate
+ */
+class MongoResourceHolder extends ResourceHolderSupport {
+
+	private @Nullable ClientSession session;
+	private MongoDbFactory dbFactory;
+
+	/**
+	 * Create a new {@link MongoResourceHolder} for a given {@link ClientSession session}.
+	 *
+	 * @param session the associated {@link ClientSession}. Can be {@literal null}.
+	 * @param dbFactory the associated {@link MongoDbFactory}. must not be {@literal null}.
+	 */
+	MongoResourceHolder(@Nullable ClientSession session, MongoDbFactory dbFactory) {
+
+		this.session = session;
+		this.dbFactory = dbFactory;
+	}
+
+	/**
+	 * @return the associated {@link ClientSession}. Can be {@literal null}.
+	 */
+	@Nullable
+	ClientSession getSession() {
+		return session;
+	}
+
+	/**
+	 * @return the required associated {@link ClientSession}.
+	 * @throws IllegalStateException if no {@link ClientSession} is associated with this {@link MongoResourceHolder}.
+	 * @since 2.1.3
+	 */
+	ClientSession getRequiredSession() {
+
+		ClientSession session = getSession();
+
+		if (session == null) {
+			throw new IllegalStateException("No session available!");
+		}
+
+		return session;
+	}
+
+	/**
+	 * @return the associated {@link MongoDbFactory}.
+	 */
+	public MongoDbFactory getDbFactory() {
+		return dbFactory;
+	}
+
+	/**
+	 * Set the {@link ClientSession} to guard.
+	 *
+	 * @param session can be {@literal null}.
+	 */
+	public void setSession(@Nullable ClientSession session) {
+		this.session = session;
+	}
+
+	/**
+	 * Only set the timeout if it does not match the {@link TransactionDefinition#TIMEOUT_DEFAULT default timeout}.
+	 *
+	 * @param seconds
+	 */
+	void setTimeoutIfNotDefaulted(int seconds) {
+
+		if (seconds != TransactionDefinition.TIMEOUT_DEFAULT) {
+			setTimeoutInSeconds(seconds);
+		}
+	}
+
+	/**
+	 * @return {@literal true} if session is not {@literal null}.
+	 */
+	boolean hasSession() {
+		return session != null;
+	}
+
+	/**
+	 * @return {@literal true} if the session is active and has not been closed.
+	 */
+	boolean hasActiveSession() {
+
+		if (!hasSession()) {
+			return false;
+		}
+
+		return hasServerSession() && !getRequiredSession().getServerSession().isClosed();
+	}
+
+	/**
+	 * @return {@literal true} if the session has an active transaction.
+	 * @since 2.1.3
+	 * @see #hasActiveSession()
+	 */
+	boolean hasActiveTransaction() {
+
+		if (!hasActiveSession()) {
+			return false;
+		}
+
+		return getRequiredSession().hasActiveTransaction();
+	}
+
+	/**
+	 * @return {@literal true} if the {@link ClientSession} has a {@link com.mongodb.session.ServerSession} associated
+	 *         that is accessible via {@link ClientSession#getServerSession()}.
+	 */
+	boolean hasServerSession() {
+
+		try {
+			return getRequiredSession().getServerSession() != null;
+		} catch (IllegalStateException serverSessionClosed) {
+			// ignore
+		}
+
+		return false;
+	}
+
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoSessionProvider.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.client.ClientSession;
+
+/**
+ * A simple interface for obtaining a {@link ClientSession} to be consumed by
+ * {@link org.springframework.data.mongodb.core.MongoOperations} and MongoDB native operations that support causal
+ * consistency and transactions.
+ *
+ * @author Christoph Strobl
+ * @currentRead Shadow's Edge - Brent Weeks
+ * @since 2.1
+ */
+@FunctionalInterface
+public interface MongoSessionProvider {
+
+	/**
+	 * Obtain a {@link ClientSession} with with given options.
+	 *
+	 * @param options must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @throws org.springframework.dao.DataAccessException
+	 */
+	ClientSession getSession(ClientSessionOptions options);
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoTransactionException.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * A specific {@link ClientSessionException} related to issues with a transaction such as aborted or non existing
+ * transactions.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public class MongoTransactionException extends ClientSessionException {
+
+	/**
+	 * Constructor for {@link MongoTransactionException}.
+	 *
+	 * @param msg the detail message. Must not be {@literal null}.
+	 */
+	public MongoTransactionException(String msg) {
+		super(msg);
+	}
+
+	/**
+	 * Constructor for {@link ClientSessionException}.
+	 *
+	 * @param msg the detail message. Can be {@literal null}.
+	 * @param cause the root cause. Can be {@literal null}.
+	 */
+	public MongoTransactionException(@Nullable String msg, @Nullable Throwable cause) {
+		super(msg, cause);
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/MongoTransactionManager.java

@@ -0,0 +1,526 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
+import org.springframework.transaction.TransactionDefinition;
+import org.springframework.transaction.TransactionException;
+import org.springframework.transaction.TransactionSystemException;
+import org.springframework.transaction.support.AbstractPlatformTransactionManager;
+import org.springframework.transaction.support.DefaultTransactionStatus;
+import org.springframework.transaction.support.ResourceTransactionManager;
+import org.springframework.transaction.support.SmartTransactionObject;
+import org.springframework.transaction.support.TransactionSynchronizationManager;
+import org.springframework.transaction.support.TransactionSynchronizationUtils;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.MongoException;
+import com.mongodb.TransactionOptions;
+import com.mongodb.client.ClientSession;
+
+/**
+ * A {@link org.springframework.transaction.PlatformTransactionManager} implementation that manages
+ * {@link ClientSession} based transactions for a single {@link MongoDbFactory}.
+ * <p />
+ * Binds a {@link ClientSession} from the specified {@link MongoDbFactory} to the thread.
+ * <p />
+ * {@link TransactionDefinition#isReadOnly() Readonly} transactions operate on a {@link ClientSession} and enable causal
+ * consistency, and also {@link ClientSession#startTransaction() start}, {@link ClientSession#commitTransaction()
+ * commit} or {@link ClientSession#abortTransaction() abort} a transaction.
+ * <p />
+ * Application code is required to retrieve the {@link com.mongodb.client.MongoDatabase} via
+ * {@link MongoDatabaseUtils#getDatabase(MongoDbFactory)} instead of a standard {@link MongoDbFactory#getDb()} call.
+ * Spring classes such as {@link org.springframework.data.mongodb.core.MongoTemplate} use this strategy implicitly.
+ * <p />
+ * By default failure of a {@literal commit} operation raises a {@link TransactionSystemException}. One may override
+ * {@link #doCommit(MongoTransactionObject)} to implement the
+ * <a href="https://docs.mongodb.com/manual/core/transactions/#retry-commit-operation">Retry Commit Operation</a>
+ * behavior as outlined in the MongoDB reference manual.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @currentRead Shadow's Edge - Brent Weeks
+ * @since 2.1
+ * @see <a href="https://www.mongodb.com/transactions">MongoDB Transaction Documentation</a>
+ * @see MongoDatabaseUtils#getDatabase(MongoDbFactory, SessionSynchronization)
+ */
+public class MongoTransactionManager extends AbstractPlatformTransactionManager
+		implements ResourceTransactionManager, InitializingBean {
+
+	private @Nullable MongoDbFactory dbFactory;
+	private @Nullable TransactionOptions options;
+
+	/**
+	 * Create a new {@link MongoTransactionManager} for bean-style usage.
+	 * <p />
+	 * <strong>Note:</strong>The {@link MongoDbFactory db factory} has to be {@link #setDbFactory(MongoDbFactory) set}
+	 * before using the instance. Use this constructor to prepare a {@link MongoTransactionManager} via a
+	 * {@link org.springframework.beans.factory.BeanFactory}.
+	 * <p />
+	 * Optionally it is possible to set default {@link TransactionOptions transaction options} defining
+	 * {@link com.mongodb.ReadConcern} and {@link com.mongodb.WriteConcern}.
+	 *
+	 * @see #setDbFactory(MongoDbFactory)
+	 * @see #setTransactionSynchronization(int)
+	 */
+	public MongoTransactionManager() {}
+
+	/**
+	 * Create a new {@link MongoTransactionManager} obtaining sessions from the given {@link MongoDbFactory}.
+	 *
+	 * @param dbFactory must not be {@literal null}.
+	 */
+	public MongoTransactionManager(MongoDbFactory dbFactory) {
+		this(dbFactory, null);
+	}
+
+	/**
+	 * Create a new {@link MongoTransactionManager} obtaining sessions from the given {@link MongoDbFactory} applying the
+	 * given {@link TransactionOptions options}, if present, when starting a new transaction.
+	 *
+	 * @param dbFactory must not be {@literal null}.
+	 * @param options can be {@literal null}.
+	 */
+	public MongoTransactionManager(MongoDbFactory dbFactory, @Nullable TransactionOptions options) {
+
+		Assert.notNull(dbFactory, "DbFactory must not be null!");
+
+		this.dbFactory = dbFactory;
+		this.options = options;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doGetTransaction()
+	 */
+	@Override
+	protected Object doGetTransaction() throws TransactionException {
+
+		MongoResourceHolder resourceHolder = (MongoResourceHolder) TransactionSynchronizationManager
+				.getResource(getRequiredDbFactory());
+		return new MongoTransactionObject(resourceHolder);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#isExistingTransaction(java.lang.Object)
+	 */
+	@Override
+	protected boolean isExistingTransaction(Object transaction) throws TransactionException {
+		return extractMongoTransaction(transaction).hasResourceHolder();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doBegin(java.lang.Object, org.springframework.transaction.TransactionDefinition)
+	 */
+	@Override
+	protected void doBegin(Object transaction, TransactionDefinition definition) throws TransactionException {
+
+		MongoTransactionObject mongoTransactionObject = extractMongoTransaction(transaction);
+
+		MongoResourceHolder resourceHolder = newResourceHolder(definition,
+				ClientSessionOptions.builder().causallyConsistent(true).build());
+		mongoTransactionObject.setResourceHolder(resourceHolder);
+
+		if (logger.isDebugEnabled()) {
+			logger
+					.debug(String.format("About to start transaction for session %s.", debugString(resourceHolder.getSession())));
+		}
+
+		try {
+			mongoTransactionObject.startTransaction(options);
+		} catch (MongoException ex) {
+			throw new TransactionSystemException(String.format("Could not start Mongo transaction for session %s.",
+					debugString(mongoTransactionObject.getSession())), ex);
+		}
+
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format("Started transaction for session %s.", debugString(resourceHolder.getSession())));
+		}
+
+		resourceHolder.setSynchronizedWithTransaction(true);
+		TransactionSynchronizationManager.bindResource(getRequiredDbFactory(), resourceHolder);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doSuspend(java.lang.Object)
+	 */
+	@Override
+	protected Object doSuspend(Object transaction) throws TransactionException {
+
+		MongoTransactionObject mongoTransactionObject = extractMongoTransaction(transaction);
+		mongoTransactionObject.setResourceHolder(null);
+
+		return TransactionSynchronizationManager.unbindResource(getRequiredDbFactory());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doResume(java.lang.Object, java.lang.Object)
+	 */
+	@Override
+	protected void doResume(@Nullable Object transaction, Object suspendedResources) {
+		TransactionSynchronizationManager.bindResource(getRequiredDbFactory(), suspendedResources);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doCommit(org.springframework.transaction.support.DefaultTransactionStatus)
+	 */
+	@Override
+	protected final void doCommit(DefaultTransactionStatus status) throws TransactionException {
+
+		MongoTransactionObject mongoTransactionObject = extractMongoTransaction(status);
+
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format("About to commit transaction for session %s.",
+					debugString(mongoTransactionObject.getSession())));
+		}
+
+		try {
+			doCommit(mongoTransactionObject);
+		} catch (Exception ex) {
+
+			throw new TransactionSystemException(String.format("Could not commit Mongo transaction for session %s.",
+					debugString(mongoTransactionObject.getSession())), ex);
+		}
+	}
+
+	/**
+	 * Customization hook to perform an actual commit of the given transaction.<br />
+	 * If a commit operation encounters an error, the MongoDB driver throws a {@link MongoException} holding
+	 * {@literal error labels}. <br />
+	 * By default those labels are ignored, nevertheless one might check for
+	 * {@link MongoException#UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL transient commit errors labels} and retry the the
+	 * commit. <br />
+	 * <code>
+	 *     <pre>
+	 * int retries = 3;
+	 * do {
+	 *     try {
+	 *         transactionObject.commitTransaction();
+	 *         break;
+	 *     } catch (MongoException ex) {
+	 *         if (!ex.hasErrorLabel(MongoException.UNKNOWN_TRANSACTION_COMMIT_RESULT_LABEL)) {
+	 *             throw ex;
+	 *         }
+	 *     }
+	 *     Thread.sleep(500);
+	 * } while (--retries > 0);
+	 *     </pre>
+	 * </code>
+	 *
+	 * @param transactionObject never {@literal null}.
+	 * @throws Exception in case of transaction errors.
+	 */
+	protected void doCommit(MongoTransactionObject transactionObject) throws Exception {
+		transactionObject.commitTransaction();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doRollback(org.springframework.transaction.support.DefaultTransactionStatus)
+	 */
+	@Override
+	protected void doRollback(DefaultTransactionStatus status) throws TransactionException {
+
+		MongoTransactionObject mongoTransactionObject = extractMongoTransaction(status);
+
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format("About to abort transaction for session %s.",
+					debugString(mongoTransactionObject.getSession())));
+		}
+
+		try {
+			mongoTransactionObject.abortTransaction();
+		} catch (MongoException ex) {
+
+			throw new TransactionSystemException(String.format("Could not abort Mongo transaction for session %s.",
+					debugString(mongoTransactionObject.getSession())), ex);
+		}
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doSetRollbackOnly(org.springframework.transaction.support.DefaultTransactionStatus)
+	 */
+	@Override
+	protected void doSetRollbackOnly(DefaultTransactionStatus status) throws TransactionException {
+
+		MongoTransactionObject transactionObject = extractMongoTransaction(status);
+		transactionObject.getRequiredResourceHolder().setRollbackOnly();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * org.springframework.transaction.support.AbstractPlatformTransactionManager#doCleanupAfterCompletion(java.lang.Object)
+	 */
+	@Override
+	protected void doCleanupAfterCompletion(Object transaction) {
+
+		Assert.isInstanceOf(MongoTransactionObject.class, transaction,
+				() -> String.format("Expected to find a %s but it turned out to be %s.", MongoTransactionObject.class,
+						transaction.getClass()));
+
+		MongoTransactionObject mongoTransactionObject = (MongoTransactionObject) transaction;
+
+		// Remove the connection holder from the thread.
+		TransactionSynchronizationManager.unbindResource(getRequiredDbFactory());
+		mongoTransactionObject.getRequiredResourceHolder().clear();
+
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format("About to release Session %s after transaction.",
+					debugString(mongoTransactionObject.getSession())));
+		}
+
+		mongoTransactionObject.closeSession();
+	}
+
+	/**
+	 * Set the {@link MongoDbFactory} that this instance should manage transactions for.
+	 *
+	 * @param dbFactory must not be {@literal null}.
+	 */
+	public void setDbFactory(MongoDbFactory dbFactory) {
+
+		Assert.notNull(dbFactory, "DbFactory must not be null!");
+		this.dbFactory = dbFactory;
+	}
+
+	/**
+	 * Set the {@link TransactionOptions} to be applied when starting transactions.
+	 *
+	 * @param options can be {@literal null}.
+	 */
+	public void setOptions(@Nullable TransactionOptions options) {
+		this.options = options;
+	}
+
+	/**
+	 * Get the {@link MongoDbFactory} that this instance manages transactions for.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public MongoDbFactory getDbFactory() {
+		return dbFactory;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.transaction.support.ResourceTransactionManager#getResourceFactory()
+	 */
+	@Override
+	public MongoDbFactory getResourceFactory() {
+		return getRequiredDbFactory();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
+	 */
+	@Override
+	public void afterPropertiesSet() {
+		getRequiredDbFactory();
+	}
+
+	private MongoResourceHolder newResourceHolder(TransactionDefinition definition, ClientSessionOptions options) {
+
+		MongoDbFactory dbFactory = getResourceFactory();
+
+		MongoResourceHolder resourceHolder = new MongoResourceHolder(dbFactory.getSession(options), dbFactory);
+		resourceHolder.setTimeoutIfNotDefaulted(determineTimeout(definition));
+
+		return resourceHolder;
+	}
+
+	/**
+	 * @throws IllegalStateException if {@link #dbFactory} is {@literal null}.
+	 */
+	private MongoDbFactory getRequiredDbFactory() {
+
+		Assert.state(dbFactory != null,
+				"MongoTransactionManager operates upon a MongoDbFactory. Did you forget to provide one? It's required.");
+
+		return dbFactory;
+	}
+
+	private static MongoTransactionObject extractMongoTransaction(Object transaction) {
+
+		Assert.isInstanceOf(MongoTransactionObject.class, transaction,
+				() -> String.format("Expected to find a %s but it turned out to be %s.", MongoTransactionObject.class,
+						transaction.getClass()));
+
+		return (MongoTransactionObject) transaction;
+	}
+
+	private static MongoTransactionObject extractMongoTransaction(DefaultTransactionStatus status) {
+
+		Assert.isInstanceOf(MongoTransactionObject.class, status.getTransaction(),
+				() -> String.format("Expected to find a %s but it turned out to be %s.", MongoTransactionObject.class,
+						status.getTransaction().getClass()));
+
+		return (MongoTransactionObject) status.getTransaction();
+	}
+
+	private static String debugString(@Nullable ClientSession session) {
+
+		if (session == null) {
+			return "null";
+		}
+
+		String debugString = String.format("[%s@%s ", ClassUtils.getShortName(session.getClass()),
+				Integer.toHexString(session.hashCode()));
+
+		try {
+			if (session.getServerSession() != null) {
+				debugString += String.format("id = %s, ", session.getServerSession().getIdentifier());
+				debugString += String.format("causallyConsistent = %s, ", session.isCausallyConsistent());
+				debugString += String.format("txActive = %s, ", session.hasActiveTransaction());
+				debugString += String.format("txNumber = %d, ", session.getServerSession().getTransactionNumber());
+				debugString += String.format("closed = %d, ", session.getServerSession().isClosed());
+				debugString += String.format("clusterTime = %s", session.getClusterTime());
+			} else {
+				debugString += "id = n/a";
+				debugString += String.format("causallyConsistent = %s, ", session.isCausallyConsistent());
+				debugString += String.format("txActive = %s, ", session.hasActiveTransaction());
+				debugString += String.format("clusterTime = %s", session.getClusterTime());
+			}
+		} catch (RuntimeException e) {
+			debugString += String.format("error = %s", e.getMessage());
+		}
+
+		debugString += "]";
+
+		return debugString;
+	}
+
+	/**
+	 * MongoDB specific transaction object, representing a {@link MongoResourceHolder}. Used as transaction object by
+	 * {@link MongoTransactionManager}.
+	 *
+	 * @author Christoph Strobl
+	 * @author Mark Paluch
+	 * @since 2.1
+	 * @see MongoResourceHolder
+	 */
+	protected static class MongoTransactionObject implements SmartTransactionObject {
+
+		private @Nullable MongoResourceHolder resourceHolder;
+
+		MongoTransactionObject(@Nullable MongoResourceHolder resourceHolder) {
+			this.resourceHolder = resourceHolder;
+		}
+
+		/**
+		 * Set the {@link MongoResourceHolder}.
+		 *
+		 * @param resourceHolder can be {@literal null}.
+		 */
+		void setResourceHolder(@Nullable MongoResourceHolder resourceHolder) {
+			this.resourceHolder = resourceHolder;
+		}
+
+		/**
+		 * @return {@literal true} if a {@link MongoResourceHolder} is set.
+		 */
+		final boolean hasResourceHolder() {
+			return resourceHolder != null;
+		}
+
+		/**
+		 * Start a MongoDB transaction optionally given {@link TransactionOptions}.
+		 *
+		 * @param options can be {@literal null}
+		 */
+		void startTransaction(@Nullable TransactionOptions options) {
+
+			ClientSession session = getRequiredSession();
+			if (options != null) {
+				session.startTransaction(options);
+			} else {
+				session.startTransaction();
+			}
+		}
+
+		/**
+		 * Commit the transaction.
+		 */
+		public void commitTransaction() {
+			getRequiredSession().commitTransaction();
+		}
+
+		/**
+		 * Rollback (abort) the transaction.
+		 */
+		public void abortTransaction() {
+			getRequiredSession().abortTransaction();
+		}
+
+		/**
+		 * Close a {@link ClientSession} without regard to its transactional state.
+		 */
+		void closeSession() {
+
+			ClientSession session = getRequiredSession();
+			if (session.getServerSession() != null && !session.getServerSession().isClosed()) {
+				session.close();
+			}
+		}
+
+		@Nullable
+		public ClientSession getSession() {
+			return resourceHolder != null ? resourceHolder.getSession() : null;
+		}
+
+		private MongoResourceHolder getRequiredResourceHolder() {
+
+			Assert.state(resourceHolder != null, "MongoResourceHolder is required but not present. o_O");
+			return resourceHolder;
+		}
+
+		private ClientSession getRequiredSession() {
+
+			ClientSession session = getSession();
+			Assert.state(session != null, "A Session is required but it turned out to be null.");
+			return session;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see  org.springframework.transaction.support.SmartTransactionObject#isRollbackOnly()
+		 */
+		@Override
+		public boolean isRollbackOnly() {
+			return this.resourceHolder != null && this.resourceHolder.isRollbackOnly();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see  org.springframework.transaction.support.SmartTransactionObject#flush()
+		 */
+		@Override
+		public void flush() {
+			TransactionSynchronizationUtils.triggerFlush();
+		}
+
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/ReactiveMongoDatabaseFactory.java

@@ -16,19 +16,25 @@
 
 package org.springframework.data.mongodb;
 
+import reactor.core.publisher.Mono;
+
+import org.bson.codecs.configuration.CodecRegistry;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.core.MongoExceptionTranslator;
 
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.reactivestreams.client.ClientSession;
 import com.mongodb.reactivestreams.client.MongoDatabase;
 
 /**
  * Interface for factories creating reactive {@link MongoDatabase} instances.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.0
  */
-public interface ReactiveMongoDatabaseFactory {
+public interface ReactiveMongoDatabaseFactory extends CodecRegistryProvider {
 
 	/**
 	 * Creates a default {@link MongoDatabase} instance.
@@ -53,4 +59,33 @@ public interface ReactiveMongoDatabaseFactory {
 	 * @return will never be {@literal null}.
 	 */
 	PersistenceExceptionTranslator getExceptionTranslator();
+
+	/**
+	 * Get the underlying {@link CodecRegistry} used by the reactive MongoDB Java driver.
+	 *
+	 * @return never {@literal null}.
+	 */
+	@Override
+	default CodecRegistry getCodecRegistry() {
+		return getMongoDatabase().getCodecRegistry();
+	}
+
+	/**
+	 * Obtain a {@link Mono} emitting a {@link ClientSession} for given {@link ClientSessionOptions options}.
+	 *
+	 * @param options must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	Mono<ClientSession> getSession(ClientSessionOptions options);
+
+	/**
+	 * Obtain a {@link ClientSession} bound instance of {@link ReactiveMongoDatabaseFactory} returning
+	 * {@link MongoDatabase} instances that are aware and bound to the given session.
+	 *
+	 * @param session must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	ReactiveMongoDatabaseFactory withSession(ClientSession session);
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/SessionAwareMethodInterceptor.java

@@ -0,0 +1,215 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.Optional;
+import java.util.function.BiFunction;
+
+import org.aopalliance.intercept.MethodInterceptor;
+import org.aopalliance.intercept.MethodInvocation;
+import org.springframework.core.MethodClassKey;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
+import org.springframework.util.ReflectionUtils;
+
+import com.mongodb.WriteConcern;
+import com.mongodb.session.ClientSession;
+
+/**
+ * {@link MethodInterceptor} implementation looking up and invoking an alternative target method having
+ * {@link ClientSession} as its first argument. This allows seamless integration with the existing code base.
+ * <p />
+ * The {@link MethodInterceptor} is aware of methods on {@code MongoCollection} that my return new instances of itself
+ * like (eg. {@link com.mongodb.reactivestreams.client.MongoCollection#withWriteConcern(WriteConcern)} and decorate them
+ * if not already proxied.
+ *
+ * @param <D> Type of the actual Mongo Database.
+ * @param <C> Type of the actual Mongo Collection.
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+public class SessionAwareMethodInterceptor<D, C> implements MethodInterceptor {
+
+	private static final MethodCache METHOD_CACHE = new MethodCache();
+
+	private final ClientSession session;
+	private final ClientSessionOperator collectionDecorator;
+	private final ClientSessionOperator databaseDecorator;
+	private final Object target;
+	private final Class<?> targetType;
+	private final Class<?> collectionType;
+	private final Class<?> databaseType;
+	private final Class<? extends ClientSession> sessionType;
+
+	/**
+	 * Create a new SessionAwareMethodInterceptor for given target.
+	 *
+	 * @param session the {@link ClientSession} to be used on invocation.
+	 * @param target the original target object.
+	 * @param databaseType the MongoDB database type
+	 * @param databaseDecorator a {@link ClientSessionOperator} used to create the proxy for an imperative / reactive
+	 *          {@code MongoDatabase}.
+	 * @param collectionType the MongoDB collection type.
+	 * @param collectionDecorator a {@link ClientSessionOperator} used to create the proxy for an imperative / reactive
+	 *          {@code MongoCollection}.
+	 * @param <T> target object type.
+	 */
+	public <T> SessionAwareMethodInterceptor(ClientSession session, T target, Class<? extends ClientSession> sessionType,
+			Class<D> databaseType, ClientSessionOperator<D> databaseDecorator, Class<C> collectionType,
+			ClientSessionOperator<C> collectionDecorator) {
+
+		Assert.notNull(session, "ClientSession must not be null!");
+		Assert.notNull(target, "Target must not be null!");
+		Assert.notNull(sessionType, "SessionType must not be null!");
+		Assert.notNull(databaseType, "Database type must not be null!");
+		Assert.notNull(databaseDecorator, "Database ClientSessionOperator must not be null!");
+		Assert.notNull(collectionType, "Collection type must not be null!");
+		Assert.notNull(collectionDecorator, "Collection ClientSessionOperator must not be null!");
+
+		this.session = session;
+		this.target = target;
+		this.databaseType = ClassUtils.getUserClass(databaseType);
+		this.collectionType = ClassUtils.getUserClass(collectionType);
+		this.collectionDecorator = collectionDecorator;
+		this.databaseDecorator = databaseDecorator;
+
+		this.targetType = ClassUtils.isAssignable(databaseType, target.getClass()) ? databaseType : collectionType;
+		this.sessionType = sessionType;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.aopalliance.intercept.MethodInterceptor(org.aopalliance.intercept.MethodInvocation)
+	 */
+	@Nullable
+	@Override
+	public Object invoke(MethodInvocation methodInvocation) throws Throwable {
+
+		if (requiresDecoration(methodInvocation.getMethod())) {
+
+			Object target = methodInvocation.proceed();
+			if (target instanceof Proxy) {
+				return target;
+			}
+
+			return decorate(target);
+		}
+
+		if (!requiresSession(methodInvocation.getMethod())) {
+			return methodInvocation.proceed();
+		}
+
+		Optional<Method> targetMethod = METHOD_CACHE.lookup(methodInvocation.getMethod(), targetType, sessionType);
+
+		return !targetMethod.isPresent() ? methodInvocation.proceed()
+				: ReflectionUtils.invokeMethod(targetMethod.get(), target,
+						prependSessionToArguments(session, methodInvocation));
+	}
+
+	private boolean requiresDecoration(Method method) {
+
+		return ClassUtils.isAssignable(databaseType, method.getReturnType())
+				|| ClassUtils.isAssignable(collectionType, method.getReturnType());
+	}
+
+	@SuppressWarnings("unchecked")
+	protected Object decorate(Object target) {
+
+		return ClassUtils.isAssignable(databaseType, target.getClass()) ? databaseDecorator.apply(session, target)
+				: collectionDecorator.apply(session, target);
+	}
+
+	private static boolean requiresSession(Method method) {
+
+		if (method.getParameterCount() == 0
+				|| !ClassUtils.isAssignable(ClientSession.class, method.getParameterTypes()[0])) {
+			return true;
+		}
+
+		return false;
+	}
+
+	private static Object[] prependSessionToArguments(ClientSession session, MethodInvocation invocation) {
+
+		Object[] args = new Object[invocation.getArguments().length + 1];
+
+		args[0] = session;
+		System.arraycopy(invocation.getArguments(), 0, args, 1, invocation.getArguments().length);
+
+		return args;
+	}
+
+	/**
+	 * Simple {@link Method} to {@link Method} caching facility for {@link ClientSession} overloaded targets.
+	 *
+	 * @since 2.1
+	 * @author Christoph Strobl
+	 */
+	static class MethodCache {
+
+		private final ConcurrentReferenceHashMap<MethodClassKey, Optional<Method>> cache = new ConcurrentReferenceHashMap<>();
+
+		/**
+		 * Lookup the target {@link Method}.
+		 *
+		 * @param method
+		 * @param targetClass
+		 * @return
+		 */
+		Optional<Method> lookup(Method method, Class<?> targetClass, Class<? extends ClientSession> sessionType) {
+
+			return cache.computeIfAbsent(new MethodClassKey(method, targetClass),
+					val -> Optional.ofNullable(findTargetWithSession(method, targetClass, sessionType)));
+		}
+
+		@Nullable
+		private Method findTargetWithSession(Method sourceMethod, Class<?> targetType,
+				Class<? extends ClientSession> sessionType) {
+
+			Class<?>[] argTypes = sourceMethod.getParameterTypes();
+			Class<?>[] args = new Class<?>[argTypes.length + 1];
+			args[0] = sessionType;
+			System.arraycopy(argTypes, 0, args, 1, argTypes.length);
+
+			return ReflectionUtils.findMethod(targetType, sourceMethod.getName(), args);
+		}
+
+		/**
+		 * Check whether the cache contains an entry for {@link Method} and {@link Class}.
+		 *
+		 * @param method
+		 * @param targetClass
+		 * @return
+		 */
+		boolean contains(Method method, Class<?> targetClass) {
+			return cache.containsKey(new MethodClassKey(method, targetClass));
+		}
+	}
+
+	/**
+	 * Represents an operation upon two operands of the same type, producing a result of the same type as the operands
+	 * accepting {@link ClientSession}. This is a specialization of {@link BiFunction} for the case where the operands and
+	 * the result are all of the same type.
+	 *
+	 * @param <T> the type of the operands and result of the operator
+	 */
+	public interface ClientSessionOperator<T> extends BiFunction<ClientSession, T, T> {}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/SessionSynchronization.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb;
+
+/**
+ * {@link SessionSynchronization} is used along with {@link org.springframework.data.mongodb.core.MongoTemplate} to
+ * define in which type of transactions to participate if any.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+public enum SessionSynchronization {
+
+	/**
+	 * Synchronize with any transaction even with empty transactions and initiate a MongoDB transaction when doing so by
+	 * registering a MongoDB specific {@link org.springframework.transaction.support.ResourceHolderSynchronization}.
+	 */
+	ALWAYS,
+
+	/**
+	 * Synchronize with native MongoDB transactions initiated via {@link MongoTransactionManager}.
+	 */
+	ON_ACTUAL_TRANSACTION;
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractMongoClientConfiguration.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.mongodb.MongoDbFactory;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.SimpleMongoClientDbFactory;
+import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
+import org.springframework.data.mongodb.core.convert.DbRefResolver;
+import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
+import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.mapping.Document;
+import org.springframework.lang.Nullable;
+
+import com.mongodb.client.MongoClient;
+
+/**
+ * Base class for Spring Data MongoDB configuration using JavaConfig with {@link com.mongodb.client.MongoClient}.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ * @see MongoConfigurationSupport
+ * @see AbstractMongoConfiguration
+ */
+@Configuration
+public abstract class AbstractMongoClientConfiguration extends MongoConfigurationSupport {
+
+	/**
+	 * Return the {@link MongoClient} instance to connect to. Annotate with {@link Bean} in case you want to expose a
+	 * {@link MongoClient} instance to the {@link org.springframework.context.ApplicationContext}.
+	 *
+	 * @return
+	 */
+	public abstract MongoClient mongoClient();
+
+	/**
+	 * Creates a {@link MongoTemplate}.
+	 *
+	 * @return
+	 */
+	@Bean
+	public MongoTemplate mongoTemplate() throws Exception {
+		return new MongoTemplate(mongoDbFactory(), mappingMongoConverter());
+	}
+
+	/**
+	 * Creates a {@link SimpleMongoDbFactory} to be used by the {@link MongoTemplate}. Will use the {@link MongoClient}
+	 * instance configured in {@link #mongoClient()}.
+	 *
+	 * @see #mongoClient()
+	 * @see #mongoTemplate()
+	 * @return
+	 */
+	@Bean
+	public MongoDbFactory mongoDbFactory() {
+		return new SimpleMongoClientDbFactory(mongoClient(), getDatabaseName());
+	}
+
+	/**
+	 * Return the base package to scan for mapped {@link Document}s. Will return the package name of the configuration
+	 * class' (the concrete class, not this one here) by default. So if you have a {@code com.acme.AppConfig} extending
+	 * {@link AbstractMongoClientConfiguration} the base package will be considered {@code com.acme} unless the method is
+	 * overridden to implement alternate behavior.
+	 *
+	 * @return the base package to scan for mapped {@link Document} classes or {@literal null} to not enable scanning for
+	 *         entities.
+	 * @deprecated use {@link #getMappingBasePackages()} instead.
+	 */
+	@Deprecated
+	@Nullable
+	protected String getMappingBasePackage() {
+
+		Package mappingBasePackage = getClass().getPackage();
+		return mappingBasePackage == null ? null : mappingBasePackage.getName();
+	}
+
+	/**
+	 * Creates a {@link MappingMongoConverter} using the configured {@link #mongoDbFactory()} and
+	 * {@link #mongoMappingContext()}. Will get {@link #customConversions()} applied.
+	 *
+	 * @see #customConversions()
+	 * @see #mongoMappingContext()
+	 * @see #mongoDbFactory()
+	 * @return
+	 * @throws Exception
+	 */
+	@Bean
+	public MappingMongoConverter mappingMongoConverter() throws Exception {
+
+		DbRefResolver dbRefResolver = new DefaultDbRefResolver(mongoDbFactory());
+		MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, mongoMappingContext());
+		converter.setCustomConversions(customConversions());
+
+		return converter;
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractMongoConfiguration.java

@@ -29,7 +29,10 @@ import org.springframework.lang.Nullable;
 import com.mongodb.MongoClient;
 
 /**
- * Base class for Spring Data MongoDB configuration using JavaConfig.
+ * Base class for Spring Data MongoDB configuration using JavaConfig with {@link com.mongodb.MongoClient}.
+ * <p />
+ * <strong>INFO:</strong>In case you want to use {@link com.mongodb.client.MongoClients} for configuration please refer
+ * to {@link AbstractMongoClientConfiguration}.
  *
  * @author Mark Pollack
  * @author Oliver Gierke
@@ -38,10 +41,10 @@ import com.mongodb.MongoClient;
  * @author Christoph Strobl
  * @author Mark Paluch
  * @see MongoConfigurationSupport
+ * @see AbstractMongoClientConfiguration
  */
 @Configuration
-public abstract class
-AbstractMongoConfiguration extends MongoConfigurationSupport {
+public abstract class AbstractMongoConfiguration extends MongoConfigurationSupport {
 
 	/**
 	 * Return the {@link MongoClient} instance to connect to. Annotate with {@link Bean} in case you want to expose a
@@ -63,7 +66,7 @@ AbstractMongoConfiguration extends MongoConfigurationSupport {
 
 	/**
 	 * Creates a {@link SimpleMongoDbFactory} to be used by the {@link MongoTemplate}. Will use the {@link MongoClient}
-	 * instance configured in {@link #mongo()}.
+	 * instance configured in {@link #mongoClient()}.
 	 *
 	 * @see #mongoClient()
 	 * @see #mongoTemplate()
@@ -111,4 +114,5 @@ AbstractMongoConfiguration extends MongoConfigurationSupport {
 
 		return converter;
 	}
+
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractReactiveMongoConfiguration.java

@@ -22,6 +22,7 @@ import org.springframework.data.mongodb.core.ReactiveMongoOperations;
 import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
 import org.springframework.data.mongodb.core.SimpleReactiveMongoDatabaseFactory;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.convert.NoOpDbRefResolver;
 
 import com.mongodb.reactivestreams.client.MongoClient;
 
@@ -80,8 +81,7 @@ public abstract class AbstractReactiveMongoConfiguration extends MongoConfigurat
 	@Bean
 	public MappingMongoConverter mappingMongoConverter() throws Exception {
 
-		MappingMongoConverter converter = new MappingMongoConverter(ReactiveMongoTemplate.NO_OP_REF_RESOLVER,
-				mongoMappingContext());
+		MappingMongoConverter converter = new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mongoMappingContext());
 		converter.setCustomConversions(customConversions());
 
 		return converter;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/BeanNames.java

@@ -17,7 +17,7 @@ package org.springframework.data.mongodb.config;
 
 /**
  * Constants to declare bean names used by the namespace configuration.
- * 
+ *
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Martin Baumgartner

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/EnableMongoAuditing.java

@@ -28,7 +28,7 @@ import org.springframework.data.domain.AuditorAware;
 
 /**
  * Annotation to enable auditing in MongoDB via annotation configuration.
- * 
+ *
  * @author Thomas Darimont
  * @author Oliver Gierke
  */
@@ -41,21 +41,21 @@ public @interface EnableMongoAuditing {
 
 	/**
 	 * Configures the {@link AuditorAware} bean to be used to lookup the current principal.
-	 * 
+	 *
 	 * @return
 	 */
 	String auditorAwareRef() default "";
 
 	/**
 	 * Configures whether the creation and modification dates are set. Defaults to {@literal true}.
-	 * 
+	 *
 	 * @return
 	 */
 	boolean setDates() default true;
 
 	/**
 	 * Configures whether the entity shall be marked as modified on creation. Defaults to {@literal true}.
-	 * 
+	 *
 	 * @return
 	 */
 	boolean modifyOnCreate() default true;
@@ -63,7 +63,7 @@ public @interface EnableMongoAuditing {
 	/**
 	 * Configures a {@link DateTimeProvider} bean name that allows customizing the {@link org.joda.time.DateTime} to be
 	 * used for setting creation and modification dates.
-	 * 
+	 *
 	 * @return
 	 */
 	String dateTimeProviderRef() default "";

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/GeoJsonConfiguration.java

@@ -21,7 +21,7 @@ import org.springframework.data.web.config.SpringDataJacksonModules;
 
 /**
  * Configuration class to expose {@link GeoJsonModule} as a Spring bean.
- * 
+ *
  * @author Oliver Gierke
  * @author Jens Schauder
  */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/GridFsTemplateParser.java

@@ -29,7 +29,7 @@ import org.w3c.dom.Element;
 
 /**
  * {@link BeanDefinitionParser} to parse {@code gridFsTemplate} elements into {@link BeanDefinition}s.
- * 
+ *
  * @author Martin Baumgartner
  */
 class GridFsTemplateParser extends AbstractBeanDefinitionParser {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoAuditingBeanDefinitionParser.java

@@ -33,12 +33,12 @@ import org.w3c.dom.Element;
 /**
  * {@link BeanDefinitionParser} to register a {@link AuditingEventListener} to transparently set auditing information on
  * an entity.
- * 
+ *
  * @author Oliver Gierke
  */
 public class MongoAuditingBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser#getBeanClass(org.w3c.dom.Element)
 	 */
@@ -47,7 +47,7 @@ public class MongoAuditingBeanDefinitionParser extends AbstractSingleBeanDefinit
 		return AuditingEventListener.class;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.xml.AbstractBeanDefinitionParser#shouldGenerateId()
 	 */
@@ -56,7 +56,7 @@ public class MongoAuditingBeanDefinitionParser extends AbstractSingleBeanDefinit
 		return true;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser#doParse(org.w3c.dom.Element, org.springframework.beans.factory.xml.ParserContext, org.springframework.beans.factory.support.BeanDefinitionBuilder)
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoAuditingRegistrar.java

@@ -37,13 +37,13 @@ import org.springframework.util.Assert;
 
 /**
  * {@link ImportBeanDefinitionRegistrar} to enable {@link EnableMongoAuditing} annotation.
- * 
+ *
  * @author Thomas Darimont
  * @author Oliver Gierke
  */
 class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAnnotation()
 	 */
@@ -52,7 +52,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 		return EnableMongoAuditing.class;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAuditingHandlerBeanName()
 	 */
@@ -61,7 +61,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 		return "mongoAuditingHandler";
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#registerBeanDefinitions(org.springframework.core.type.AnnotationMetadata, org.springframework.beans.factory.support.BeanDefinitionRegistry)
 	 */
@@ -74,7 +74,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 		super.registerBeanDefinitions(annotationMetadata, registry);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAuditHandlerBeanDefinitionBuilder(org.springframework.data.auditing.config.AuditingConfiguration)
 	 */
@@ -92,7 +92,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 		return configureDefaultAuditHandlerAttributes(configuration, builder);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#registerAuditListener(org.springframework.beans.factory.config.BeanDefinition, org.springframework.beans.factory.support.BeanDefinitionRegistry)
 	 */
@@ -125,14 +125,14 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 
 		/**
 		 * Creates a new {@link MongoMappingContextLookup} for the given {@link MappingMongoConverter}.
-		 * 
+		 *
 		 * @param converter must not be {@literal null}.
 		 */
 		public MongoMappingContextLookup(MappingMongoConverter converter) {
 			this.converter = converter;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.beans.factory.FactoryBean#getObject()
 		 */
@@ -141,7 +141,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 			return converter.getMappingContext();
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.beans.factory.FactoryBean#getObjectType()
 		 */
@@ -150,7 +150,7 @@ class MongoAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 			return MappingContext.class;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.beans.factory.FactoryBean#isSingleton()
 		 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoClientParser.java

@@ -29,13 +29,13 @@ import org.w3c.dom.Element;
 
 /**
  * Parser for {@code mongo-client} definitions.
- * 
+ *
  * @author Christoph Strobl
  * @since 1.7
  */
 public class MongoClientParser implements BeanDefinitionParser {
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.xml.BeanDefinitionParser#parse(org.w3c.dom.Element, org.springframework.beans.factory.xml.ParserContext)
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoCredentialPropertyEditor.java

@@ -17,7 +17,6 @@ package org.springframework.data.mongodb.config;
 
 import java.beans.PropertyEditorSupport;
 import java.io.UnsupportedEncodingException;
-import java.lang.reflect.Method;
 import java.net.URLDecoder;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -27,7 +26,6 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.springframework.lang.Nullable;
-import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
 import com.mongodb.MongoCredential;
@@ -102,20 +100,12 @@ public class MongoCredentialPropertyEditor extends PropertyEditorSupport {
 						verifyDatabasePresent(database);
 						credentials.add(MongoCredential.createScramSha1Credential(userNameAndPassword[0], database,
 								userNameAndPassword[1].toCharArray()));
-					} else if ("SCRAM-SHA-256".equals(authMechanism)) {
-
-						Method createScramSha256Credential = ReflectionUtils.findMethod(MongoCredential.class,
-								"createScramSha256Credential", String.class, String.class, char[].class);
-
-						if (createScramSha256Credential == null) {
-							throw new IllegalArgumentException(
-									"SCRAM-SHA-256 auth mechanism is available as of MongoDB 4 and MongoDB Java Driver 3.8! Please make sure to use at least those versions.");
-						}
+					} else if (MongoCredential.SCRAM_SHA_256_MECHANISM.equals(authMechanism)) {
 
 						verifyUsernameAndPasswordPresent(userNameAndPassword);
 						verifyDatabasePresent(database);
-						credentials.add(MongoCredential.class.cast(ReflectionUtils.invokeMethod(createScramSha256Credential, null,
-								userNameAndPassword[0], database, userNameAndPassword[1].toCharArray())));
+						credentials.add(MongoCredential.createScramSha256Credential(userNameAndPassword[0], database,
+								userNameAndPassword[1].toCharArray()));
 					} else {
 						throw new IllegalArgumentException(
 								String.format("Cannot create MongoCredentials for unknown auth mechanism '%s'!", authMechanism));

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoNamespaceHandler.java

@@ -19,7 +19,7 @@ import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
 
 /**
  * {@link org.springframework.beans.factory.xml.NamespaceHandler} for Mongo DB configuration.
- * 
+ *
  * @author Oliver Gierke
  * @author Martin Baumgartner
  * @author Christoph Strobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoParsingUtils.java

@@ -30,7 +30,7 @@ import org.w3c.dom.Element;
 
 /**
  * Utility methods for {@link BeanDefinitionParser} implementations for MongoDB.
- * 
+ *
  * @author Mark Pollack
  * @author Oliver Gierke
  * @author Thomas Darimont
@@ -43,7 +43,7 @@ abstract class MongoParsingUtils {
 
 	/**
 	 * Parses the mongo replica-set element.
-	 * 
+	 *
 	 * @param parserContext the parser context
 	 * @param element the mongo element
 	 * @param mongoBuilder the bean definition builder to populate
@@ -56,7 +56,7 @@ abstract class MongoParsingUtils {
 	/**
 	 * Parses the {@code mongo:client-options} sub-element. Populates the given attribute factory with the proper
 	 * attributes.
-	 * 
+	 *
 	 * @param element must not be {@literal null}.
 	 * @param mongoClientBuilder must not be {@literal null}.
 	 * @return
@@ -102,7 +102,7 @@ abstract class MongoParsingUtils {
 	/**
 	 * Returns the {@link BeanDefinitionBuilder} to build a {@link BeanDefinition} for a
 	 * {@link WriteConcernPropertyEditor}.
-	 * 
+	 *
 	 * @return
 	 */
 	static BeanDefinitionBuilder getWriteConcernPropertyEditorBuilder() {
@@ -135,7 +135,7 @@ abstract class MongoParsingUtils {
 	/**
 	 * Returns the {@link BeanDefinitionBuilder} to build a {@link BeanDefinition} for a
 	 * {@link ReadPreferencePropertyEditor}.
-	 * 
+	 *
 	 * @return
 	 * @since 1.7
 	 */
@@ -153,7 +153,7 @@ abstract class MongoParsingUtils {
 	/**
 	 * Returns the {@link BeanDefinitionBuilder} to build a {@link BeanDefinition} for a
 	 * {@link MongoCredentialPropertyEditor}.
-	 * 
+	 *
 	 * @return
 	 * @since 1.7
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/MongoTemplateParser.java

@@ -33,13 +33,13 @@ import org.w3c.dom.Element;
 
 /**
  * {@link BeanDefinitionParser} to parse {@code template} elements into {@link BeanDefinition}s.
- * 
+ *
  * @author Martin Baumgartner
  * @author Oliver Gierke
  */
 class MongoTemplateParser extends AbstractBeanDefinitionParser {
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.beans.factory.xml.AbstractBeanDefinitionParser#resolveId(org.w3c.dom.Element, org.springframework.beans.factory.support.AbstractBeanDefinition, org.springframework.beans.factory.xml.ParserContext)
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/ReadPreferencePropertyEditor.java

@@ -23,7 +23,7 @@ import com.mongodb.ReadPreference;
 
 /**
  * Parse a {@link String} to a {@link ReadPreference}.
- * 
+ *
  * @author Christoph Strobl
  * @since 1.7
  */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/StringToWriteConcernConverter.java

@@ -21,12 +21,12 @@ import com.mongodb.WriteConcern;
 
 /**
  * Converter to create {@link WriteConcern} instances from String representations.
- * 
+ *
  * @author Oliver Gierke
  */
 public class StringToWriteConcernConverter implements Converter<String, WriteConcern> {
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/WriteConcernPropertyEditor.java

@@ -27,7 +27,7 @@ import com.mongodb.WriteConcern;
  * {@link WriteConcern#valueOf(String)}, use the well known {@link WriteConcern} value, otherwise pass the string as is
  * to the constructor of the write concern. There is no support for other constructor signatures when parsing from a
  * string value.
- * 
+ *
  * @author Mark Pollack
  * @author Christoph Strobl
  */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/AggregationUtil.java

@@ -17,6 +17,8 @@ package org.springframework.data.mongodb.core;
 
 import lombok.AllArgsConstructor;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -24,13 +26,19 @@ import java.util.stream.Collectors;
 import org.bson.Document;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mongodb.core.aggregation.Aggregation;
+import org.springframework.data.mongodb.core.aggregation.AggregationOperation;
 import org.springframework.data.mongodb.core.aggregation.AggregationOperationContext;
+import org.springframework.data.mongodb.core.aggregation.AggregationOptions;
+import org.springframework.data.mongodb.core.aggregation.CountOperation;
 import org.springframework.data.mongodb.core.aggregation.TypeBasedAggregationOperationContext;
 import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
 import org.springframework.data.mongodb.core.convert.QueryMapper;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.mongodb.core.query.CriteriaDefinition;
+import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -39,7 +47,7 @@ import org.springframework.util.ObjectUtils;
  *
  * @author Christoph Strobl
  * @author Mark Paluch
- * @since 2.0.8
+ * @since 2.1
  */
 @AllArgsConstructor
 class AggregationUtil {
@@ -78,16 +86,13 @@ class AggregationUtil {
 	 * @param context
 	 * @return
 	 */
-	Document createPipeline(String collectionName, Aggregation aggregation, AggregationOperationContext context) {
+	List<Document> createPipeline(Aggregation aggregation, AggregationOperationContext context) {
 
 		if (!ObjectUtils.nullSafeEquals(context, Aggregation.DEFAULT_CONTEXT)) {
-			return aggregation.toDocument(collectionName, context);
+			return aggregation.toPipeline(context);
 		}
 
-		Document command = aggregation.toDocument(collectionName, context);
-		command.put("pipeline", mapAggregationPipeline(command.get("pipeline", List.class)));
-
-		return command;
+		return mapAggregationPipeline(aggregation.toPipeline(context));
 	}
 
 	/**
@@ -110,6 +115,53 @@ class AggregationUtil {
 		return command;
 	}
 
+	/**
+	 * Create a {@code $count} aggregation for {@link Query} and optionally a {@link Class entity class}.
+	 *
+	 * @param query must not be {@literal null}.
+	 * @param entityClass can be {@literal null} if the {@link Query} object is empty.
+	 * @return the {@link Aggregation} pipeline definition to run a {@code $count} aggregation.
+	 */
+	Aggregation createCountAggregation(Query query, @Nullable Class<?> entityClass) {
+
+		List<AggregationOperation> pipeline = computeCountAggregationPipeline(query, entityClass);
+
+		Aggregation aggregation = entityClass != null ? Aggregation.newAggregation(entityClass, pipeline)
+				: Aggregation.newAggregation(pipeline);
+		aggregation.withOptions(AggregationOptions.builder().collation(query.getCollation().orElse(null)).build());
+
+		return aggregation;
+	}
+
+	private List<AggregationOperation> computeCountAggregationPipeline(Query query, @Nullable Class<?> entityType) {
+
+		CountOperation count = Aggregation.count().as("totalEntityCount");
+		if (query.getQueryObject().isEmpty()) {
+			return Collections.singletonList(count);
+		}
+
+		Assert.notNull(entityType, "Entity type must not be null!");
+
+		Document mappedQuery = queryMapper.getMappedObject(query.getQueryObject(),
+				mappingContext.getPersistentEntity(entityType));
+
+		CriteriaDefinition criteria = new CriteriaDefinition() {
+
+			@Override
+			public Document getCriteriaObject() {
+				return mappedQuery;
+			}
+
+			@Nullable
+			@Override
+			public String getKey() {
+				return null;
+			}
+		};
+
+		return Arrays.asList(Aggregation.match(criteria), count);
+	}
+
 	private List<Document> mapAggregationPipeline(List<Document> pipeline) {
 
 		return pipeline.stream().map(val -> queryMapper.getMappedObject(val, Optional.empty()))

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ChangeStreamEvent.java

@@ -0,0 +1,190 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.EqualsAndHashCode;
+
+import java.time.Instant;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
+
+import org.bson.BsonValue;
+import org.bson.Document;
+import org.springframework.data.mongodb.core.convert.MongoConverter;
+import org.springframework.data.mongodb.core.messaging.Message;
+import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
+
+import com.mongodb.client.model.changestream.ChangeStreamDocument;
+import com.mongodb.client.model.changestream.OperationType;
+
+/**
+ * {@link Message} implementation specific to MongoDB <a href="https://docs.mongodb.com/manual/changeStreams/">Change
+ * Streams</a>.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+@EqualsAndHashCode
+public class ChangeStreamEvent<T> {
+
+	@SuppressWarnings("rawtypes") //
+	private static final AtomicReferenceFieldUpdater<ChangeStreamEvent, Object> CONVERTED_UPDATER = AtomicReferenceFieldUpdater
+			.newUpdater(ChangeStreamEvent.class, Object.class, "converted");
+
+	private final @Nullable ChangeStreamDocument<Document> raw;
+
+	private final Class<T> targetType;
+	private final MongoConverter converter;
+
+	// accessed through CONVERTED_UPDATER.
+	private volatile @Nullable T converted;
+
+	/**
+	 * @param raw can be {@literal null}.
+	 * @param targetType must not be {@literal null}.
+	 * @param converter must not be {@literal null}.
+	 */
+	public ChangeStreamEvent(@Nullable ChangeStreamDocument<Document> raw, Class<T> targetType,
+			MongoConverter converter) {
+
+		this.raw = raw;
+		this.targetType = targetType;
+		this.converter = converter;
+	}
+
+	/**
+	 * Get the raw {@link ChangeStreamDocument} as emitted by the driver.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public ChangeStreamDocument<Document> getRaw() {
+		return raw;
+	}
+
+	/**
+	 * Get the {@link ChangeStreamDocument#getClusterTime() cluster time} as {@link Instant} the event was emitted at.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public Instant getTimestamp() {
+
+		return raw != null && raw.getClusterTime() != null
+				? converter.getConversionService().convert(raw.getClusterTime(), Instant.class) : null;
+	}
+
+	/**
+	 * Get the {@link ChangeStreamDocument#getResumeToken() resume token} for this event.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public BsonValue getResumeToken() {
+		return raw != null ? raw.getResumeToken() : null;
+	}
+
+	/**
+	 * Get the {@link ChangeStreamDocument#getOperationType() operation type} for this event.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public OperationType getOperationType() {
+		return raw != null ? raw.getOperationType() : null;
+	}
+
+	/**
+	 * Get the database name the event was originated at.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public String getDatabaseName() {
+		return raw != null ? raw.getNamespace().getDatabaseName() : null;
+	}
+
+	/**
+	 * Get the collection name the event was originated at.
+	 *
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	public String getCollectionName() {
+		return raw != null ? raw.getNamespace().getCollectionName() : null;
+	}
+
+	/**
+	 * Get the potentially converted {@link ChangeStreamDocument#getFullDocument()}.
+	 *
+	 * @return {@literal null} when {@link #getRaw()} or {@link ChangeStreamDocument#getFullDocument()} is
+	 *         {@literal null}.
+	 */
+	@Nullable
+	public T getBody() {
+
+		if (raw == null) {
+			return null;
+		}
+
+		Document fullDocument = raw.getFullDocument();
+
+		if (fullDocument == null) {
+			return targetType.cast(fullDocument);
+		}
+
+		return getConverted(fullDocument);
+	}
+
+	@SuppressWarnings("unchecked")
+	private T getConverted(Document fullDocument) {
+		return (T) doGetConverted(fullDocument);
+	}
+
+	private Object doGetConverted(Document fullDocument) {
+
+		Object result = CONVERTED_UPDATER.get(this);
+
+		if (result != null) {
+			return result;
+		}
+
+		if (ClassUtils.isAssignable(Document.class, fullDocument.getClass())) {
+
+			result = converter.read(targetType, fullDocument);
+			return CONVERTED_UPDATER.compareAndSet(this, null, result) ? result : CONVERTED_UPDATER.get(this);
+		}
+
+		if (converter.getConversionService().canConvert(fullDocument.getClass(), targetType)) {
+
+			result = converter.getConversionService().convert(fullDocument, targetType);
+			return CONVERTED_UPDATER.compareAndSet(this, null, result) ? result : CONVERTED_UPDATER.get(this);
+		}
+
+		throw new IllegalArgumentException(String.format("No converter found capable of converting %s to %s",
+				fullDocument.getClass(), targetType));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "ChangeStreamEvent {" + "raw=" + raw + ", targetType=" + targetType + '}';
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ChangeStreamOptions.java

@@ -0,0 +1,243 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.EqualsAndHashCode;
+
+import java.time.Instant;
+import java.util.Arrays;
+import java.util.Optional;
+
+import org.bson.BsonValue;
+import org.bson.Document;
+import org.springframework.data.mongodb.core.aggregation.Aggregation;
+import org.springframework.data.mongodb.core.query.Collation;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+import com.mongodb.client.model.changestream.ChangeStreamDocument;
+import com.mongodb.client.model.changestream.FullDocument;
+
+/**
+ * Options applicable to MongoDB <a href="https://docs.mongodb.com/manual/changeStreams/">Change Streams</a>. Intended
+ * to be used along with {@link org.springframework.data.mongodb.core.messaging.ChangeStreamRequest} in a sync world as
+ * well {@link ReactiveMongoOperations} if you prefer it that way.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+@EqualsAndHashCode
+public class ChangeStreamOptions {
+
+	private @Nullable Object filter;
+	private @Nullable BsonValue resumeToken;
+	private @Nullable FullDocument fullDocumentLookup;
+	private @Nullable Collation collation;
+	private @Nullable Instant resumeTimestamp;
+
+	protected ChangeStreamOptions() {}
+
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<Object> getFilter() {
+		return Optional.ofNullable(filter);
+	}
+
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<BsonValue> getResumeToken() {
+		return Optional.ofNullable(resumeToken);
+	}
+
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<FullDocument> getFullDocumentLookup() {
+		return Optional.ofNullable(fullDocumentLookup);
+	}
+
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<Collation> getCollation() {
+		return Optional.ofNullable(collation);
+	}
+
+	/**
+	 * @return {@link Optional#empty()} if not set.
+	 */
+	public Optional<Instant> getResumeTimestamp() {
+		return Optional.ofNullable(resumeTimestamp);
+	}
+
+	/**
+	 * @return empty {@link ChangeStreamOptions}.
+	 */
+	public static ChangeStreamOptions empty() {
+		return ChangeStreamOptions.builder().build();
+	}
+
+	/**
+	 * Obtain a shiny new {@link ChangeStreamOptionsBuilder} and start defining options in this fancy fluent way. Just
+	 * don't forget to call {@link ChangeStreamOptionsBuilder#build() build()} when your're done.
+	 *
+	 * @return new instance of {@link ChangeStreamOptionsBuilder}.
+	 */
+	public static ChangeStreamOptionsBuilder builder() {
+		return new ChangeStreamOptionsBuilder();
+	}
+
+	/**
+	 * Builder for creating {@link ChangeStreamOptions}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	public static class ChangeStreamOptionsBuilder {
+
+		private @Nullable Object filter;
+		private @Nullable BsonValue resumeToken;
+		private @Nullable FullDocument fullDocumentLookup;
+		private @Nullable Collation collation;
+		private @Nullable Instant resumeTimestamp;
+
+		private ChangeStreamOptionsBuilder() {}
+
+		/**
+		 * Set the collation to use.
+		 *
+		 * @param collation must not be {@literal null} nor {@literal empty}.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder collation(Collation collation) {
+
+			Assert.notNull(collation, "Collation must not be null nor empty!");
+
+			this.collation = collation;
+			return this;
+		}
+
+		/**
+		 * Set the filter to apply.
+		 * <p/>
+		 * Fields on aggregation expression root level are prefixed to map to fields contained in
+		 * {@link ChangeStreamDocument#getFullDocument() fullDocument}. However {@literal operationType}, {@literal ns},
+		 * {@literal documentKey} and {@literal fullDocument} are reserved words that will be omitted, and therefore taken
+		 * as given, during the mapping procedure. You may want to have a look at the
+		 * <a href="https://docs.mongodb.com/manual/reference/change-events/">structure of Change Events</a>.
+		 * <p/>
+		 * Use {@link org.springframework.data.mongodb.core.aggregation.TypedAggregation} to ensure filter expressions are
+		 * mapped to domain type fields.
+		 *
+		 * @param filter the {@link Aggregation Aggregation pipeline} to apply for filtering events. Must not be
+		 *          {@literal null}.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder filter(Aggregation filter) {
+
+			Assert.notNull(filter, "Filter must not be null!");
+
+			this.filter = filter;
+			return this;
+		}
+
+		/**
+		 * Set the plain filter chain to apply.
+		 *
+		 * @param filter must not be {@literal null} nor contain {@literal null} values.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder filter(Document... filter) {
+
+			Assert.noNullElements(filter, "Filter must not contain null values");
+
+			this.filter = Arrays.asList(filter);
+			return this;
+		}
+
+		/**
+		 * Set the resume token (typically a {@link org.bson.BsonDocument} containing a {@link org.bson.BsonBinary binary
+		 * token}) after which to start with listening.
+		 *
+		 * @param resumeToken must not be {@literal null}.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder resumeToken(BsonValue resumeToken) {
+
+			Assert.notNull(resumeToken, "ResumeToken must not be null!");
+
+			this.resumeToken = resumeToken;
+			return this;
+		}
+
+		/**
+		 * Set the {@link FullDocument} lookup to {@link FullDocument#UPDATE_LOOKUP}.
+		 *
+		 * @return this.
+		 * @see #fullDocumentLookup(FullDocument)
+		 */
+		public ChangeStreamOptionsBuilder returnFullDocumentOnUpdate() {
+			return fullDocumentLookup(FullDocument.UPDATE_LOOKUP);
+		}
+
+		/**
+		 * Set the {@link FullDocument} lookup to use.
+		 *
+		 * @param lookup must not be {@literal null}.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder fullDocumentLookup(FullDocument lookup) {
+
+			Assert.notNull(lookup, "Lookup must not be null!");
+
+			this.fullDocumentLookup = lookup;
+			return this;
+		}
+
+		/**
+		 * Set the cluster time to resume from.
+		 *
+		 * @param resumeTimestamp must not be {@literal null}.
+		 * @return this.
+		 */
+		public ChangeStreamOptionsBuilder resumeAt(Instant resumeTimestamp) {
+
+			Assert.notNull(resumeTimestamp, "ResumeTimestamp must not be null!");
+
+			this.resumeTimestamp = resumeTimestamp;
+			return this;
+		}
+
+		/**
+		 * @return the built {@link ChangeStreamOptions}
+		 */
+		public ChangeStreamOptions build() {
+
+			ChangeStreamOptions options = new ChangeStreamOptions();
+
+			options.filter = filter;
+			options.resumeToken = resumeToken;
+			options.fullDocumentLookup = fullDocumentLookup;
+			options.collation = collation;
+			options.resumeTimestamp = resumeTimestamp;
+
+			return options;
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/CollectionOptions.java

@@ -15,18 +15,27 @@
  */
 package org.springframework.data.mongodb.core;
 
+import lombok.RequiredArgsConstructor;
+
 import java.util.Optional;
 
 import org.springframework.data.mongodb.core.query.Collation;
+import org.springframework.data.mongodb.core.schema.MongoJsonSchema;
+import org.springframework.data.mongodb.core.validation.Validator;
+import org.springframework.data.util.Optionals;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
+import com.mongodb.client.model.ValidationAction;
+import com.mongodb.client.model.ValidationLevel;
+
 /**
  * Provides a simple wrapper to encapsulate the variety of settings you can use when creating a collection.
  *
  * @author Thomas Risberg
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Andreas Zink
  */
 public class CollectionOptions {
 
@@ -34,6 +43,7 @@ public class CollectionOptions {
 	private @Nullable Long size;
 	private @Nullable Boolean capped;
 	private @Nullable Collation collation;
+	private ValidationOptions validationOptions;
 
 	/**
 	 * Constructs a new <code>CollectionOptions</code> instance.
@@ -46,16 +56,17 @@ public class CollectionOptions {
 	 */
 	@Deprecated
 	public CollectionOptions(@Nullable Long size, @Nullable Long maxDocuments, @Nullable Boolean capped) {
-		this(size, maxDocuments, capped, null);
+		this(size, maxDocuments, capped, null, ValidationOptions.none());
 	}
 
 	private CollectionOptions(@Nullable Long size, @Nullable Long maxDocuments, @Nullable Boolean capped,
-			@Nullable Collation collation) {
+			@Nullable Collation collation, ValidationOptions validationOptions) {
 
 		this.maxDocuments = maxDocuments;
 		this.size = size;
 		this.capped = capped;
 		this.collation = collation;
+		this.validationOptions = validationOptions;
 	}
 
 	/**
@@ -69,7 +80,7 @@ public class CollectionOptions {
 
 		Assert.notNull(collation, "Collation must not be null!");
 
-		return new CollectionOptions(null, null, null, collation);
+		return new CollectionOptions(null, null, null, collation, ValidationOptions.none());
 	}
 
 	/**
@@ -79,7 +90,7 @@ public class CollectionOptions {
 	 * @since 2.0
 	 */
 	public static CollectionOptions empty() {
-		return new CollectionOptions(null, null, null, null);
+		return new CollectionOptions(null, null, null, null, ValidationOptions.none());
 	}
 
 	/**
@@ -90,7 +101,7 @@ public class CollectionOptions {
 	 * @since 2.0
 	 */
 	public CollectionOptions capped() {
-		return new CollectionOptions(size, maxDocuments, true, collation);
+		return new CollectionOptions(size, maxDocuments, true, collation, validationOptions);
 	}
 
 	/**
@@ -101,7 +112,7 @@ public class CollectionOptions {
 	 * @since 2.0
 	 */
 	public CollectionOptions maxDocuments(long maxDocuments) {
-		return new CollectionOptions(size, maxDocuments, capped, collation);
+		return new CollectionOptions(size, maxDocuments, capped, collation, validationOptions);
 	}
 
 	/**
@@ -112,7 +123,7 @@ public class CollectionOptions {
 	 * @since 2.0
 	 */
 	public CollectionOptions size(long size) {
-		return new CollectionOptions(size, maxDocuments, capped, collation);
+		return new CollectionOptions(size, maxDocuments, capped, collation, validationOptions);
 	}
 
 	/**
@@ -123,7 +134,127 @@ public class CollectionOptions {
 	 * @since 2.0
 	 */
 	public CollectionOptions collation(@Nullable Collation collation) {
-		return new CollectionOptions(size, maxDocuments, capped, collation);
+		return new CollectionOptions(size, maxDocuments, capped, collation, validationOptions);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationOptions} set to given
+	 * {@link MongoJsonSchema}.
+	 *
+	 * @param schema can be {@literal null}.
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions schema(@Nullable MongoJsonSchema schema) {
+		return validator(Validator.schema(schema));
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationOptions} set to given
+	 * {@link Validator}.
+	 *
+	 * @param validator can be {@literal null}.
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions validator(@Nullable Validator validator) {
+		return validation(validationOptions.validator(validator));
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationLevel} set to
+	 * {@link ValidationLevel#OFF}.
+	 *
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions disableValidation() {
+		return schemaValidationLevel(ValidationLevel.OFF);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationLevel} set to
+	 * {@link ValidationLevel#STRICT}.
+	 *
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions strictValidation() {
+		return schemaValidationLevel(ValidationLevel.STRICT);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationLevel} set to
+	 * {@link ValidationLevel#MODERATE}.
+	 *
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions moderateValidation() {
+		return schemaValidationLevel(ValidationLevel.MODERATE);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationAction} set to
+	 * {@link ValidationAction#WARN}.
+	 *
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions warnOnValidationError() {
+		return schemaValidationAction(ValidationAction.WARN);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationAction} set to
+	 * {@link ValidationAction#ERROR}.
+	 *
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions failOnValidationError() {
+		return schemaValidationAction(ValidationAction.ERROR);
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationLevel} set given
+	 * {@link ValidationLevel}.
+	 *
+	 * @param validationLevel must not be {@literal null}.
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions schemaValidationLevel(ValidationLevel validationLevel) {
+
+		Assert.notNull(validationLevel, "ValidationLevel must not be null!");
+		return validation(validationOptions.validationLevel(validationLevel));
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with already given settings and {@code validationAction} set given
+	 * {@link ValidationAction}.
+	 *
+	 * @param validationAction must not be {@literal null}.
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions schemaValidationAction(ValidationAction validationAction) {
+
+		Assert.notNull(validationAction, "ValidationAction must not be null!");
+		return validation(validationOptions.validationAction(validationAction));
+	}
+
+	/**
+	 * Create new {@link CollectionOptions} with the given {@link ValidationOptions}.
+	 *
+	 * @param validationOptions must not be {@literal null}. Use {@link ValidationOptions#none()} to remove validation.
+	 * @return new {@link CollectionOptions}.
+	 * @since 2.1
+	 */
+	public CollectionOptions validation(ValidationOptions validationOptions) {
+
+		Assert.notNull(validationOptions, "ValidationOptions must not be null!");
+		return new CollectionOptions(size, maxDocuments, capped, collation, validationOptions);
 	}
 
 	/**
@@ -163,4 +294,104 @@ public class CollectionOptions {
 	public Optional<Collation> getCollation() {
 		return Optional.ofNullable(collation);
 	}
+
+	/**
+	 * Get the {@link MongoJsonSchema} for the collection.
+	 *
+	 * @return {@link Optional#empty()} if not set.
+	 * @since 2.1
+	 */
+	public Optional<ValidationOptions> getValidationOptions() {
+		return validationOptions.isEmpty() ? Optional.empty() : Optional.of(validationOptions);
+	}
+
+	/**
+	 * Encapsulation of ValidationOptions options.
+	 *
+	 * @author Christoph Strobl
+	 * @author Andreas Zink
+	 * @since 2.1
+	 */
+	@RequiredArgsConstructor
+	public static class ValidationOptions {
+
+		private static final ValidationOptions NONE = new ValidationOptions(null, null, null);
+
+		private final @Nullable Validator validator;
+		private final @Nullable ValidationLevel validationLevel;
+		private final @Nullable ValidationAction validationAction;
+
+		/**
+		 * Create an empty {@link ValidationOptions}.
+		 *
+		 * @return never {@literal null}.
+		 */
+		public static ValidationOptions none() {
+			return NONE;
+		}
+
+		/**
+		 * Define the {@link Validator} to be used for document validation.
+		 *
+		 * @param validator can be {@literal null}.
+		 * @return new instance of {@link ValidationOptions}.
+		 */
+		public ValidationOptions validator(@Nullable Validator validator) {
+			return new ValidationOptions(validator, validationLevel, validationAction);
+		}
+
+		/**
+		 * Define the validation level to apply.
+		 *
+		 * @param validationLevel can be {@literal null}.
+		 * @return new instance of {@link ValidationOptions}.
+		 */
+		public ValidationOptions validationLevel(ValidationLevel validationLevel) {
+			return new ValidationOptions(validator, validationLevel, validationAction);
+		}
+
+		/**
+		 * Define the validation action to take.
+		 *
+		 * @param validationAction can be {@literal null}.
+		 * @return new instance of {@link ValidationOptions}.
+		 */
+		public ValidationOptions validationAction(ValidationAction validationAction) {
+			return new ValidationOptions(validator, validationLevel, validationAction);
+		}
+
+		/**
+		 * Get the {@link Validator} to use.
+		 *
+		 * @return never {@literal null}.
+		 */
+		public Optional<Validator> getValidator() {
+			return Optional.ofNullable(validator);
+		}
+
+		/**
+		 * Get the {@code validationLevel} to apply.
+		 *
+		 * @return {@link Optional#empty()} if not set.
+		 */
+		public Optional<ValidationLevel> getValidationLevel() {
+			return Optional.ofNullable(validationLevel);
+		}
+
+		/**
+		 * Get the {@code validationAction} to perform.
+		 *
+		 * @return @return {@link Optional#empty()} if not set.
+		 */
+		public Optional<ValidationAction> getValidationAction() {
+			return Optional.ofNullable(validationAction);
+		}
+
+		/**
+		 * @return {@literal true} if no arguments set.
+		 */
+		boolean isEmpty() {
+			return !Optionals.isAnyPresent(getValidator(), getValidationAction(), getValidationLevel());
+		}
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/CursorPreparer.java

@@ -21,7 +21,7 @@ import com.mongodb.client.FindIterable;
 
 /**
  * Simple callback interface to allow customization of a {@link FindIterable}.
- * 
+ *
  * @author Oliver Gierke
  * @author Christoph Strobl
  */
@@ -29,7 +29,7 @@ interface CursorPreparer {
 
 	/**
 	 * Prepare the given cursor (apply limits, skips and so on). Returns the prepared cursor.
-	 * 
+	 *
 	 * @param cursor
 	 */
 	FindIterable<Document> prepare(FindIterable<Document> cursor);

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultBulkOperations.java

@@ -274,19 +274,10 @@ class DefaultBulkOperations implements BulkOperations {
 	public com.mongodb.bulk.BulkWriteResult execute() {
 
 		try {
-
-			MongoCollection<Document> collection = mongoOperations.getCollection(collectionName);
-			if (defaultWriteConcern != null) {
-				collection = collection.withWriteConcern(defaultWriteConcern);
-			}
-
-			return collection.bulkWrite(models.stream().map(this::mapWriteModel).collect(Collectors.toList()), bulkOptions);
-
-		} catch (BulkWriteException o_O) {
-
-			DataAccessException toThrow = exceptionTranslator.translateExceptionIfPossible(o_O);
-			throw toThrow == null ? o_O : toThrow;
-
+			
+			return mongoOperations.execute(collectionName, collection -> {
+				return collection.bulkWrite(models.stream().map(this::mapWriteModel).collect(Collectors.toList()), bulkOptions);
+			});
 		} finally {
 			this.bulkOptions = getBulkWriteOptions(bulkOperationContext.getBulkMode());
 		}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DefaultIndexOperations.java

@@ -15,8 +15,6 @@
  */
 package org.springframework.data.mongodb.core;
 
-import static org.springframework.data.mongodb.core.MongoTemplate.*;
-
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -50,18 +48,22 @@ public class DefaultIndexOperations implements IndexOperations {
 
 	private static final String PARTIAL_FILTER_EXPRESSION_KEY = "partialFilterExpression";
 
-	private final MongoDbFactory mongoDbFactory;
 	private final String collectionName;
 	private final QueryMapper mapper;
 	private final @Nullable Class<?> type;
 
+	private MongoOperations mongoOperations;
+
 	/**
 	 * Creates a new {@link DefaultIndexOperations}.
 	 *
 	 * @param mongoDbFactory must not be {@literal null}.
 	 * @param collectionName must not be {@literal null}.
 	 * @param queryMapper must not be {@literal null}.
+	 * @deprecated since 2.1. Please use
+	 *             {@link DefaultIndexOperations#DefaultIndexOperations(MongoOperations, String, Class)}.
 	 */
+	@Deprecated
 	public DefaultIndexOperations(MongoDbFactory mongoDbFactory, String collectionName, QueryMapper queryMapper) {
 		this(mongoDbFactory, collectionName, queryMapper, null);
 	}
@@ -74,7 +76,10 @@ public class DefaultIndexOperations implements IndexOperations {
 	 * @param queryMapper must not be {@literal null}.
 	 * @param type Type used for mapping potential partial index filter expression. Can be {@literal null}.
 	 * @since 1.10
+	 * @deprecated since 2.1. Please use
+	 *             {@link DefaultIndexOperations#DefaultIndexOperations(MongoOperations, String, Class)}.
 	 */
+	@Deprecated
 	public DefaultIndexOperations(MongoDbFactory mongoDbFactory, String collectionName, QueryMapper queryMapper,
 			@Nullable Class<?> type) {
 
@@ -82,10 +87,29 @@ public class DefaultIndexOperations implements IndexOperations {
 		Assert.notNull(collectionName, "Collection name can not be null!");
 		Assert.notNull(queryMapper, "QueryMapper must not be null!");
 
-		this.mongoDbFactory = mongoDbFactory;
 		this.collectionName = collectionName;
 		this.mapper = queryMapper;
 		this.type = type;
+		this.mongoOperations = new MongoTemplate(mongoDbFactory);
+	}
+
+	/**
+	 * Creates a new {@link DefaultIndexOperations}.
+	 *
+	 * @param mongoOperations must not be {@literal null}.
+	 * @param collectionName must not be {@literal null} or empty.
+	 * @param type can be {@literal null}.
+	 * @since 2.1
+	 */
+	public DefaultIndexOperations(MongoOperations mongoOperations, String collectionName, @Nullable Class<?> type) {
+
+		Assert.notNull(mongoOperations, "MongoOperations must not be null!");
+		Assert.hasText(collectionName, "Collection name must not be null or empty!");
+
+		this.mongoOperations = mongoOperations;
+		this.mapper = new QueryMapper(mongoOperations.getConverter());
+		this.collectionName = collectionName;
+		this.type = type;
 	}
 
 	/*
@@ -187,11 +211,10 @@ public class DefaultIndexOperations implements IndexOperations {
 
 		Assert.notNull(callback, "CollectionCallback must not be null!");
 
-		try {
-			MongoCollection<Document> collection = mongoDbFactory.getDb().getCollection(collectionName);
-			return callback.doInCollection(collection);
-		} catch (RuntimeException e) {
-			throw potentiallyConvertRuntimeException(e, mongoDbFactory.getExceptionTranslator());
+		if (type != null) {
+			return mongoOperations.execute(type, callback);
 		}
+
+		return mongoOperations.execute(collectionName, callback);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/DocumentCallbackHandler.java

@@ -26,7 +26,7 @@ import com.mongodb.MongoException;
  * about exception handling. {@MongoException}s will be caught and translated by the calling MongoTemplate An
  * DocumentCallbackHandler is typically stateful: It keeps the result state within the object, to be available later for
  * later inspection.
- * 
+ *
  * @author Mark Pollack
  * @author Grame Rocher
  * @author Oliver Gierke

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/EntityOperations.java

@@ -0,0 +1,683 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.AccessLevel;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
+import java.util.Collection;
+import java.util.Map;
+
+import org.bson.Document;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.dao.InvalidDataAccessApiUsageException;
+import org.springframework.data.mapping.IdentifierAccessor;
+import org.springframework.data.mapping.MappingException;
+import org.springframework.data.mapping.PersistentPropertyAccessor;
+import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.data.mapping.model.ConvertingPropertyAccessor;
+import org.springframework.data.mongodb.core.convert.MongoWriter;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.mongodb.core.mapping.MongoSimpleTypes;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+
+import com.mongodb.util.JSONParseException;
+
+/**
+ * Common operations performed on an entity in the context of it's mapping metadata.
+ *
+ * @author Oliver Gierke
+ * @author Mark Paluch
+ * @since 2.1
+ * @see MongoTemplate
+ * @see ReactiveMongoTemplate
+ */
+@RequiredArgsConstructor
+class EntityOperations {
+
+	private static final String ID_FIELD = "_id";
+
+	private final @NonNull MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> context;
+
+	/**
+	 * Creates a new {@link Entity} for the given bean.
+	 *
+	 * @param entity must not be {@literal null}.
+	 * @return
+	 */
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public <T> Entity<T> forEntity(T entity) {
+
+		Assert.notNull(entity, "Bean must not be null!");
+
+		if (entity instanceof String) {
+			return new UnmappedEntity(parse(entity.toString()));
+		}
+
+		if (entity instanceof Map) {
+			return new SimpleMappedEntity((Map<String, Object>) entity);
+		}
+
+		return MappedEntity.of(entity, context);
+	}
+
+	/**
+	 * Creates a new {@link AdaptibleEntity} for the given bean and {@link ConversionService}.
+	 *
+	 * @param entity must not be {@literal null}.
+	 * @param conversionService must not be {@literal null}.
+	 * @return
+	 */
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public <T> AdaptibleEntity<T> forEntity(T entity, ConversionService conversionService) {
+
+		Assert.notNull(entity, "Bean must not be null!");
+		Assert.notNull(conversionService, "ConversionService must not be null!");
+
+		if (entity instanceof String) {
+			return new UnmappedEntity(parse(entity.toString()));
+		}
+
+		if (entity instanceof Map) {
+			return new SimpleMappedEntity((Map<String, Object>) entity);
+		}
+
+		return AdaptibleMappedEntity.of(entity, context, conversionService);
+	}
+
+	public String determineCollectionName(@Nullable Class<?> entityClass) {
+
+		if (entityClass == null) {
+			throw new InvalidDataAccessApiUsageException(
+					"No class parameter provided, entity collection can't be determined!");
+		}
+
+		return context.getRequiredPersistentEntity(entityClass).getCollection();
+	}
+
+	/**
+	 * Returns the collection name to be used for the given entity.
+	 *
+	 * @param obj can be {@literal null}.
+	 * @return
+	 */
+	@Nullable
+	public String determineEntityCollectionName(@Nullable Object obj) {
+		return null == obj ? null : determineCollectionName(obj.getClass());
+	}
+
+	public Query getByIdInQuery(Collection<?> entities) {
+
+		MultiValueMap<String, Object> byIds = new LinkedMultiValueMap<>();
+
+		entities.stream() //
+				.map(this::forEntity) //
+				.forEach(it -> byIds.add(it.getIdFieldName(), it.getId()));
+
+		Criteria[] criterias = byIds.entrySet().stream() //
+				.map(it -> Criteria.where(it.getKey()).in(it.getValue())) //
+				.toArray(Criteria[]::new);
+
+		return new Query(criterias.length == 1 ? criterias[0] : new Criteria().orOperator(criterias));
+	}
+
+	/**
+	 * Returns the name of the identifier property. Considers mapping information but falls back to the MongoDB default of
+	 * {@code _id} if no identifier property can be found.
+	 *
+	 * @param type must not be {@literal null}.
+	 * @return
+	 */
+	public String getIdPropertyName(Class<?> type) {
+
+		Assert.notNull(type, "Type must not be null!");
+
+		MongoPersistentEntity<?> persistentEntity = context.getPersistentEntity(type);
+
+		if (persistentEntity != null && persistentEntity.getIdProperty() != null) {
+			return persistentEntity.getRequiredIdProperty().getName();
+		}
+
+		return ID_FIELD;
+	}
+
+	private static Document parse(String source) {
+
+		try {
+			return Document.parse(source);
+		} catch (JSONParseException | org.bson.json.JsonParseException o_O) {
+			throw new MappingException("Could not parse given String to save into a JSON document!", o_O);
+		}
+	}
+
+	/**
+	 * A representation of information about an entity.
+	 *
+	 * @author Oliver Gierke
+	 * @since 2.1
+	 */
+	interface Entity<T> {
+
+		/**
+		 * Returns the field name of the identifier of the entity.
+		 *
+		 * @return
+		 */
+		String getIdFieldName();
+
+		/**
+		 * Returns the identifier of the entity.
+		 *
+		 * @return
+		 */
+		Object getId();
+
+		/**
+		 * Returns the {@link Query} to find the entity by its identifier.
+		 *
+		 * @return
+		 */
+		Query getByIdQuery();
+
+		/**
+		 * Returns the {@link Query} to find the entity in its current version.
+		 *
+		 * @return
+		 */
+		Query getQueryForVersion();
+
+		/**
+		 * Maps the backing entity into a {@link MappedDocument} using the given {@link MongoWriter}.
+		 *
+		 * @param writer must not be {@literal null}.
+		 * @return
+		 */
+		MappedDocument toMappedDocument(MongoWriter<? super T> writer);
+
+		/**
+		 * Asserts that the identifier type is updatable in case its not already set.
+		 */
+		default void assertUpdateableIdIfNotSet() {}
+
+		/**
+		 * Returns whether the entity is versioned, i.e. if it contains a version property.
+		 *
+		 * @return
+		 */
+		default boolean isVersionedEntity() {
+			return false;
+		}
+
+		/**
+		 * Returns the value of the version if the entity has a version property, {@literal null} otherwise.
+		 *
+		 * @return
+		 */
+		@Nullable
+		Object getVersion();
+
+		/**
+		 * Returns the underlying bean.
+		 *
+		 * @return
+		 */
+		T getBean();
+
+		/**
+		 * Returns whether the entity is considered to be new.
+		 * 
+		 * @return
+		 * @since 2.1.2
+		 */
+		boolean isNew();
+	}
+
+	/**
+	 * Information and commands on an entity.
+	 *
+	 * @author Oliver Gierke
+	 * @since 2.1
+	 */
+	interface AdaptibleEntity<T> extends Entity<T> {
+
+		/**
+		 * Populates the identifier of the backing entity if it has an identifier property and there's no identifier
+		 * currently present.
+		 *
+		 * @param id must not be {@literal null}.
+		 * @return
+		 */
+		@Nullable
+		T populateIdIfNecessary(@Nullable Object id);
+
+		/**
+		 * Initializes the version property of the of the current entity if available.
+		 *
+		 * @return the entity with the version property updated if available.
+		 */
+		T initializeVersionProperty();
+
+		/**
+		 * Increments the value of the version property if available.
+		 *
+		 * @return the entity with the version property incremented if available.
+		 */
+		T incrementVersion();
+
+		/**
+		 * Returns the current version value if the entity has a version property.
+		 *
+		 * @return the current version or {@literal null} in case it's uninitialized or the entity doesn't expose a version
+		 *         property.
+		 */
+		@Nullable
+		Number getVersion();
+	}
+
+	@RequiredArgsConstructor
+	private static class UnmappedEntity<T extends Map<String, Object>> implements AdaptibleEntity<T> {
+
+		private final T map;
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getIdPropertyName()
+		 */
+		@Override
+		public String getIdFieldName() {
+			return ID_FIELD;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getId()
+		 */
+		@Override
+		public Object getId() {
+			return map.get(ID_FIELD);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getByIdQuery()
+		 */
+		@Override
+		public Query getByIdQuery() {
+			return Query.query(Criteria.where(ID_FIELD).is(map.get(ID_FIELD)));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.MutablePersistableSource#populateIdIfNecessary(java.lang.Object)
+		 */
+		@Nullable
+		@Override
+		public T populateIdIfNecessary(@Nullable Object id) {
+
+			map.put(ID_FIELD, id);
+
+			return map;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getQueryForVersion()
+		 */
+		@Override
+		public Query getQueryForVersion() {
+			throw new MappingException("Cannot query for version on plain Documents!");
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#toMappedDocument(org.springframework.data.mongodb.core.convert.MongoWriter)
+		 */
+		@Override
+		public MappedDocument toMappedDocument(MongoWriter<? super T> writer) {
+			return MappedDocument.of(map instanceof Document //
+					? (Document) map //
+					: new Document(map));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.MutablePersistableSource#initializeVersionProperty()
+		 */
+		@Override
+		public T initializeVersionProperty() {
+			return map;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.MutablePersistableSource#getVersion()
+		 */
+		@Override
+		@Nullable
+		public Number getVersion() {
+			return null;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.MutablePersistableSource#incrementVersion()
+		 */
+		@Override
+		public T incrementVersion() {
+			return map;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getBean()
+		 */
+		@Override
+		public T getBean() {
+			return map;
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.Entity#isNew()
+		 */
+		@Override
+		public boolean isNew() {
+			return map.get(ID_FIELD) != null;
+		}
+	}
+
+	private static class SimpleMappedEntity<T extends Map<String, Object>> extends UnmappedEntity<T> {
+
+		SimpleMappedEntity(T map) {
+			super(map);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#toMappedDocument(org.springframework.data.mongodb.core.convert.MongoWriter)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public MappedDocument toMappedDocument(MongoWriter<? super T> writer) {
+
+			T bean = getBean();
+			bean = (T) (bean instanceof Document //
+					? (Document) bean //
+					: new Document(bean));
+			Document document = new Document();
+			writer.write(bean, document);
+
+			return MappedDocument.of(document);
+		}
+	}
+
+	@RequiredArgsConstructor(access = AccessLevel.PROTECTED)
+	private static class MappedEntity<T> implements Entity<T> {
+
+		private final @NonNull MongoPersistentEntity<?> entity;
+		private final @NonNull IdentifierAccessor idAccessor;
+		private final @NonNull PersistentPropertyAccessor<T> propertyAccessor;
+
+		private static <T> MappedEntity<T> of(T bean,
+				MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> context) {
+
+			MongoPersistentEntity<?> entity = context.getRequiredPersistentEntity(bean.getClass());
+			IdentifierAccessor identifierAccessor = entity.getIdentifierAccessor(bean);
+			PersistentPropertyAccessor<T> propertyAccessor = entity.getPropertyAccessor(bean);
+
+			return new MappedEntity<>(entity, identifierAccessor, propertyAccessor);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getIdPropertyName()
+		 */
+		@Override
+		public String getIdFieldName() {
+			return entity.getRequiredIdProperty().getFieldName();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getId()
+		 */
+		@Override
+		public Object getId() {
+			return idAccessor.getRequiredIdentifier();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getByIdQuery()
+		 */
+		@Override
+		public Query getByIdQuery() {
+
+			if (!entity.hasIdProperty()) {
+				throw new MappingException("No id property found for object of type " + entity.getType() + "!");
+			}
+
+			MongoPersistentProperty idProperty = entity.getRequiredIdProperty();
+
+			return Query.query(Criteria.where(idProperty.getName()).is(getId()));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getQueryForVersion(java.lang.Object)
+		 */
+		@Override
+		public Query getQueryForVersion() {
+
+			MongoPersistentProperty idProperty = entity.getRequiredIdProperty();
+			MongoPersistentProperty property = entity.getRequiredVersionProperty();
+
+			return new Query(Criteria.where(idProperty.getName()).is(getId())//
+					.and(property.getName()).is(getVersion()));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#toMappedDocument(org.springframework.data.mongodb.core.convert.MongoWriter)
+		 */
+		@Override
+		public MappedDocument toMappedDocument(MongoWriter<? super T> writer) {
+
+			T bean = propertyAccessor.getBean();
+
+			Document document = new Document();
+			writer.write(bean, document);
+
+			if (document.containsKey(ID_FIELD) && document.get(ID_FIELD) == null) {
+				document.remove(ID_FIELD);
+			}
+
+			return MappedDocument.of(document);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.Entity#assertUpdateableIdIfNotSet()
+		 */
+		public void assertUpdateableIdIfNotSet() {
+
+			if (!entity.hasIdProperty()) {
+				return;
+			}
+
+			MongoPersistentProperty property = entity.getRequiredIdProperty();
+			Object propertyValue = idAccessor.getIdentifier();
+
+			if (propertyValue != null) {
+				return;
+			}
+
+			if (!MongoSimpleTypes.AUTOGENERATED_ID_TYPES.contains(property.getType())) {
+				throw new InvalidDataAccessApiUsageException(
+						String.format("Cannot autogenerate id of type %s for entity of type %s!", property.getType().getName(),
+								entity.getType().getName()));
+			}
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#isVersionedEntity()
+		 */
+		@Override
+		public boolean isVersionedEntity() {
+			return entity.hasVersionProperty();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getVersion()
+		 */
+		@Override
+		@Nullable
+		public Object getVersion() {
+			return propertyAccessor.getProperty(entity.getRequiredVersionProperty());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.PersistableSource#getBean()
+		 */
+		@Override
+		public T getBean() {
+			return propertyAccessor.getBean();
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.Entity#isNew()
+		 */
+		@Override
+		public boolean isNew() {
+			return entity.isNew(propertyAccessor.getBean());
+		}
+	}
+
+	private static class AdaptibleMappedEntity<T> extends MappedEntity<T> implements AdaptibleEntity<T> {
+
+		private final MongoPersistentEntity<?> entity;
+		private final ConvertingPropertyAccessor<T> propertyAccessor;
+		private final IdentifierAccessor identifierAccessor;
+
+		private AdaptibleMappedEntity(MongoPersistentEntity<?> entity, IdentifierAccessor identifierAccessor,
+				ConvertingPropertyAccessor<T> propertyAccessor) {
+
+			super(entity, identifierAccessor, propertyAccessor);
+
+			this.entity = entity;
+			this.propertyAccessor = propertyAccessor;
+			this.identifierAccessor = identifierAccessor;
+		}
+
+		private static <T> AdaptibleEntity<T> of(T bean,
+				MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> context,
+				ConversionService conversionService) {
+
+			MongoPersistentEntity<?> entity = context.getRequiredPersistentEntity(bean.getClass());
+			IdentifierAccessor identifierAccessor = entity.getIdentifierAccessor(bean);
+			PersistentPropertyAccessor<T> propertyAccessor = entity.getPropertyAccessor(bean);
+
+			return new AdaptibleMappedEntity<>(entity, identifierAccessor,
+					new ConvertingPropertyAccessor<>(propertyAccessor, conversionService));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.AdaptibleEntity#populateIdIfNecessary(java.lang.Object)
+		 */
+		@Nullable
+		@Override
+		public T populateIdIfNecessary(@Nullable Object id) {
+
+			if (id == null) {
+				return null;
+			}
+
+			T bean = propertyAccessor.getBean();
+			MongoPersistentProperty idProperty = entity.getIdProperty();
+
+			if (idProperty == null) {
+				return bean;
+			}
+
+			if (identifierAccessor.getIdentifier() != null) {
+				return bean;
+			}
+
+			propertyAccessor.setProperty(idProperty, id);
+
+			return propertyAccessor.getBean();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.MappedEntity#getVersion()
+		 */
+		@Override
+		@Nullable
+		public Number getVersion() {
+
+			MongoPersistentProperty versionProperty = entity.getRequiredVersionProperty();
+
+			return propertyAccessor.getProperty(versionProperty, Number.class);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.AdaptibleEntity#initializeVersionProperty()
+		 */
+		@Override
+		public T initializeVersionProperty() {
+
+			if (!entity.hasVersionProperty()) {
+				return propertyAccessor.getBean();
+			}
+
+			MongoPersistentProperty versionProperty = entity.getRequiredVersionProperty();
+
+			propertyAccessor.setProperty(versionProperty, versionProperty.getType().isPrimitive() ? 1 : 0);
+
+			return propertyAccessor.getBean();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.EntityOperations.AdaptibleEntity#incrementVersion()
+		 */
+		@Override
+		public T incrementVersion() {
+
+			MongoPersistentProperty versionProperty = entity.getRequiredVersionProperty();
+			Number version = getVersion();
+			Number nextVersion = version == null ? 0 : version.longValue() + 1;
+
+			propertyAccessor.setProperty(versionProperty, nextVersion);
+
+			return propertyAccessor.getBean();
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableAggregationOperationSupport.java

@@ -35,22 +35,10 @@ import org.springframework.util.StringUtils;
  * @author Mark Paluch
  * @since 2.0
  */
+@RequiredArgsConstructor
 class ExecutableAggregationOperationSupport implements ExecutableAggregationOperation {
 
-	private final MongoTemplate template;
-
-	/**
-	 * Create new instance of {@link ExecutableAggregationOperationSupport}.
-	 *
-	 * @param template must not be {@literal null}.
-	 * @throws IllegalArgumentException if template is {@literal null}.
-	 */
-	ExecutableAggregationOperationSupport(MongoTemplate template) {
-
-		Assert.notNull(template, "Template must not be null!");
-
-		this.template = template;
-	}
+	private final @NonNull MongoTemplate template;
 
 	/*
 	 * (non-Javadoc)
@@ -131,11 +119,11 @@ class ExecutableAggregationOperationSupport implements ExecutableAggregationOper
 				TypedAggregation<?> typedAggregation = (TypedAggregation<?>) aggregation;
 
 				if (typedAggregation.getInputType() != null) {
-					return template.determineCollectionName(typedAggregation.getInputType());
+					return template.getCollectionName(typedAggregation.getInputType());
 				}
 			}
 
-			return template.determineCollectionName(domainType);
+			return template.getCollectionName(domainType);
 		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableFindOperation.java

@@ -19,11 +19,14 @@ import java.util.List;
 import java.util.Optional;
 import java.util.stream.Stream;
 
+import org.springframework.dao.DataAccessException;
 import org.springframework.data.geo.GeoResults;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.lang.Nullable;
 
+import com.mongodb.client.MongoCollection;
+
 /**
  * {@link ExecutableFindOperation} allows creation and execution of MongoDB find operations in a fluent API style.
  * <br />
@@ -202,7 +205,7 @@ public interface ExecutableFindOperation {
 	 * @author Christoph Strobl
 	 * @since 2.0
 	 */
-	interface FindWithProjection<T> extends FindWithQuery<T> {
+	interface FindWithProjection<T> extends FindWithQuery<T>, FindDistinct {
 
 		/**
 		 * Define the target type fields should be mapped to. <br />
@@ -214,6 +217,101 @@ public interface ExecutableFindOperation {
 		 * @throws IllegalArgumentException if resultType is {@literal null}.
 		 */
 		<R> FindWithQuery<R> as(Class<R> resultType);
+
+	}
+
+	/**
+	 * Distinct Find support.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface FindDistinct {
+
+		/**
+		 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view.
+		 *
+		 * @param field name of the field. Must not be {@literal null}.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if field is {@literal null}.
+		 */
+		TerminatingDistinct<Object> distinct(String field);
+	}
+
+	/**
+	 * Result type override. Optional.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface DistinctWithProjection {
+
+		/**
+		 * Define the target type the result should be mapped to. <br />
+		 * Skip this step if you are anyway fine with the default conversion.
+		 * <dl>
+		 * <dt>{@link Object} (the default)</dt>
+		 * <dd>Result is mapped according to the {@link org.bson.BsonType} converting eg. {@link org.bson.BsonString} into
+		 * plain {@link String}, {@link org.bson.BsonInt64} to {@link Long}, etc. always picking the most concrete type with
+		 * respect to the domain types property.<br />
+		 * Any {@link org.bson.BsonType#DOCUMENT} is run through the {@link org.springframework.data.convert.EntityReader}
+		 * to obtain the domain type. <br />
+		 * Using {@link Object} also works for non strictly typed fields. Eg. a mixture different types like fields using
+		 * {@link String} in one {@link org.bson.Document} while {@link Long} in another.</dd>
+		 * <dt>Any Simple type like {@link String} or {@link Long}.</dt>
+		 * <dd>The result is mapped directly by the MongoDB Java driver and the {@link org.bson.codecs.CodeCodec Codecs} in
+		 * place. This works only for results where all documents considered for the operation use the very same type for
+		 * the field.</dd>
+		 * <dt>Any Domain type</dt>
+		 * <dd>Domain types can only be mapped if the if the result of the actual {@code distinct()} operation returns
+		 * {@link org.bson.BsonType#DOCUMENT}.</dd>
+		 * <dt>{@link org.bson.BsonValue}</dt>
+		 * <dd>Using {@link org.bson.BsonValue} allows retrieval of the raw driver specific format, which returns eg.
+		 * {@link org.bson.BsonString}.</dd>
+		 * </dl>
+		 *
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		<R> TerminatingDistinct<R> as(Class<R> resultType);
+	}
+
+	/**
+	 * Result restrictions. Optional.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface DistinctWithQuery<T> extends DistinctWithProjection {
+
+		/**
+		 * Set the filter query to be used.
+		 *
+		 * @param query must not be {@literal null}.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		TerminatingDistinct<T> matching(Query query);
+	}
+
+	/**
+	 * Terminating distinct find operations.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface TerminatingDistinct<T> extends DistinctWithQuery<T> {
+
+		/**
+		 * Get all matching distinct field values.
+		 *
+		 * @return empty {@link List} if not match found. Never {@literal null}.
+		 * @throws DataAccessException if eg. result cannot be converted correctly which may happen if the document contains
+		 *           {@link String} whereas the result type is specified as {@link Long}.
+		 */
+		List<T> all();
 	}
 
 	/**
@@ -222,5 +320,5 @@ public interface ExecutableFindOperation {
 	 * @author Christoph Strobl
 	 * @since 2.0
 	 */
-	interface ExecutableFind<T> extends FindWithCollection<T>, FindWithProjection<T> {}
+	interface ExecutableFind<T> extends FindWithCollection<T>, FindWithProjection<T>, FindDistinct {}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableFindOperationSupport.java

@@ -45,24 +45,12 @@ import com.mongodb.client.FindIterable;
  * @author Mark Paluch
  * @since 2.0
  */
+@RequiredArgsConstructor
 class ExecutableFindOperationSupport implements ExecutableFindOperation {
 
 	private static final Query ALL_QUERY = new Query();
 
-	private final MongoTemplate template;
-
-	/**
-	 * Create new {@link ExecutableFindOperationSupport}.
-	 *
-	 * @param template must not be {@literal null}.
-	 * @throws IllegalArgumentException if template is {@literal null}.
-	 */
-	ExecutableFindOperationSupport(MongoTemplate template) {
-
-		Assert.notNull(template, "Template must not be null!");
-
-		this.template = template;
-	}
+	private final @NonNull MongoTemplate template;
 
 	/*
 	 * (non-Javadoc)
@@ -205,6 +193,19 @@ class ExecutableFindOperationSupport implements ExecutableFindOperation {
 			return template.exists(query, domainType, getCollectionName());
 		}
 
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableFindOperation.FindDistinct#distinct(java.lang.String)
+		 */
+		@SuppressWarnings("unchecked")
+		@Override
+		public TerminatingDistinct<Object> distinct(String field) {
+
+			Assert.notNull(field, "Field must not be null!");
+
+			return new DistinctOperationSupport(this, field);
+		}
+
 		private List<T> doFind(@Nullable CursorPreparer preparer) {
 
 			Document queryObject = query.getQueryObject();
@@ -214,6 +215,12 @@ class ExecutableFindOperationSupport implements ExecutableFindOperation {
 					getCursorPreparer(query, preparer));
 		}
 
+		private List<T> doFindDistinct(String field) {
+
+			return template.findDistinct(query, field, getCollectionName(), domainType,
+					returnType == domainType ? (Class<T>) Object.class : returnType);
+		}
+
 		private CloseableIterator<T> doStream() {
 			return template.doStream(query, domainType, getCollectionName(), returnType);
 		}
@@ -223,7 +230,7 @@ class ExecutableFindOperationSupport implements ExecutableFindOperation {
 		}
 
 		private String getCollectionName() {
-			return StringUtils.hasText(collection) ? collection : template.determineCollectionName(domainType);
+			return StringUtils.hasText(collection) ? collection : template.getCollectionName(domainType);
 		}
 
 		private String asString() {
@@ -261,4 +268,54 @@ class ExecutableFindOperationSupport implements ExecutableFindOperation {
 			return this;
 		}
 	}
+
+	/**
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	static class DistinctOperationSupport<T> implements TerminatingDistinct<T> {
+
+		private final String field;
+		private final ExecutableFindSupport<T> delegate;
+
+		public DistinctOperationSupport(ExecutableFindSupport<T> delegate, String field) {
+
+			this.delegate = delegate;
+			this.field = field;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableFindOperation.DistinctWithProjection#as(java.lang.Class)
+		 */
+		@Override
+		@SuppressWarnings("unchecked")
+		public <R> TerminatingDistinct<R> as(Class<R> resultType) {
+
+			Assert.notNull(resultType, "ResultType must not be null!");
+
+			return new DistinctOperationSupport<>((ExecutableFindSupport) delegate.as(resultType), field);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableFindOperation.DistinctWithQuery#matching(org.springframework.data.mongodb.core.query.Query)
+		 */
+		@Override
+		public TerminatingDistinct<T> matching(Query query) {
+
+			Assert.notNull(query, "Query must not be null!");
+
+			return new DistinctOperationSupport<>((ExecutableFindSupport<T>) delegate.matching(query), field);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableFindOperation.TerminatingDistinct#all()
+		 */
+		@Override
+		public List<T> all() {
+			return delegate.doFindDistinct(field);
+		}
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableInsertOperation.java

@@ -63,17 +63,19 @@ public interface ExecutableInsertOperation {
 		 * Insert exactly one object.
 		 *
 		 * @param object must not be {@literal null}.
+		 * @return the inserted object.
 		 * @throws IllegalArgumentException if object is {@literal null}.
 		 */
-		void one(T object);
+		T one(T object);
 
 		/**
 		 * Insert a collection of objects.
 		 *
 		 * @param objects must not be {@literal null}.
+		 * @return the inserted objects.
 		 * @throws IllegalArgumentException if objects is {@literal null}.
 		 */
-		void all(Collection<? extends T> objects);
+		Collection<? extends T> all(Collection<? extends T> objects);
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableInsertOperationSupport.java

@@ -37,22 +37,10 @@ import com.mongodb.bulk.BulkWriteResult;
  * @author Mark Paluch
  * @since 2.0
  */
+@RequiredArgsConstructor
 class ExecutableInsertOperationSupport implements ExecutableInsertOperation {
 
-	private final MongoTemplate template;
-
-	/**
-	 * Create new {@link ExecutableInsertOperationSupport}.
-	 *
-	 * @param template must not be {@literal null}.
-	 * @throws IllegalArgumentException if template is {@literal null}.
-	 */
-	ExecutableInsertOperationSupport(MongoTemplate template) {
-
-		Assert.notNull(template, "Template must not be null!");
-
-		this.template = template;
-	}
+	private final @NonNull MongoTemplate template;
 
 	/*
 	 * (non-Javadoc)
@@ -84,11 +72,11 @@ class ExecutableInsertOperationSupport implements ExecutableInsertOperation {
 		 * @see org.springframework.data.mongodb.core.ExecutableInsertOperation.TerminatingInsert#insert(java.lang.Class)
 		 */
 		@Override
-		public void one(T object) {
+		public T one(T object) {
 
 			Assert.notNull(object, "Object must not be null!");
 
-			template.insert(object, getCollectionName());
+			return template.insert(object, getCollectionName());
 		}
 
 		/*
@@ -96,11 +84,11 @@ class ExecutableInsertOperationSupport implements ExecutableInsertOperation {
 		 * @see org.springframework.data.mongodb.core.ExecutableInsertOperation.TerminatingInsert#all(java.util.Collection)
 		 */
 		@Override
-		public void all(Collection<? extends T> objects) {
+		public Collection<T> all(Collection<? extends T> objects) {
 
 			Assert.notNull(objects, "Objects must not be null!");
 
-			template.insert(objects, getCollectionName());
+			return template.insert(objects, getCollectionName());
 		}
 
 		/*
@@ -141,7 +129,7 @@ class ExecutableInsertOperationSupport implements ExecutableInsertOperation {
 		}
 
 		private String getCollectionName() {
-			return StringUtils.hasText(collection) ? collection : template.determineCollectionName(domainType);
+			return StringUtils.hasText(collection) ? collection : template.getCollectionName(domainType);
 		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableMapReduceOperation.java

@@ -0,0 +1,199 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import java.util.List;
+
+import org.springframework.data.mongodb.core.ExecutableFindOperation.ExecutableFind;
+import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
+import org.springframework.data.mongodb.core.query.Query;
+
+/**
+ * {@link ExecutableMapReduceOperation} allows creation and execution of MongoDB mapReduce operations in a fluent API
+ * style. The starting {@literal domainType} is used for mapping an optional {@link Query} provided via {@code matching}
+ * into the MongoDB specific representation. By default, the originating {@literal domainType} is also used for mapping
+ * back the results from the {@link org.bson.Document}. However, it is possible to define an different
+ * {@literal returnType} via {@code as} to mapping the result.<br />
+ * The collection to operate on is by default derived from the initial {@literal domainType} and can be defined there
+ * via {@link org.springframework.data.mongodb.core.mapping.Document}. Using {@code inCollection} allows to override the
+ * collection name for the execution.
+ * 
+ * <pre>
+ *     <code>
+ *         mapReduce(Human.class)
+ *             .map("function() { emit(this.id, this.firstname) }")
+ *             .reduce("function(id, name) { return sum(id, name); }")
+ *             .inCollection("star-wars")
+ *             .as(Jedi.class)
+ *             .matching(query(where("lastname").is("skywalker")))
+ *             .all();
+ *     </code>
+ * </pre>
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public interface ExecutableMapReduceOperation {
+
+	/**
+	 * Start creating a mapReduce operation for the given {@literal domainType}.
+	 *
+	 * @param domainType must not be {@literal null}.
+	 * @return new instance of {@link ExecutableFind}.
+	 * @throws IllegalArgumentException if domainType is {@literal null}.
+	 */
+	<T> MapReduceWithMapFunction<T> mapReduce(Class<T> domainType);
+
+	/**
+	 * Trigger mapReduce execution by calling one of the terminating methods.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface TerminatingMapReduce<T> {
+
+		/**
+		 * Get the mapReduce results.
+		 *
+		 * @return never {@literal null}.
+		 */
+		List<T> all();
+	}
+
+	/**
+	 * Provide the Javascript {@code function()} used to map matching documents.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithMapFunction<T> {
+
+		/**
+		 * Set the Javascript map {@code function()}.
+		 *
+		 * @param mapFunction must not be {@literal null} nor empty.
+		 * @return new instance of {@link MapReduceWithReduceFunction}.
+		 * @throws IllegalArgumentException if {@literal mapFunction} is {@literal null} or empty.
+		 */
+		MapReduceWithReduceFunction<T> map(String mapFunction);
+
+	}
+
+	/**
+	 * Provide the Javascript {@code function()} used to reduce matching documents.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithReduceFunction<T> {
+
+		/**
+		 * Set the Javascript map {@code function()}.
+		 *
+		 * @param reduceFunction must not be {@literal null} nor empty.
+		 * @return new instance of {@link ExecutableMapReduce}.
+		 * @throws IllegalArgumentException if {@literal reduceFunction} is {@literal null} or empty.
+		 */
+		ExecutableMapReduce<T> reduce(String reduceFunction);
+
+	}
+
+	/**
+	 * Collection override (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithCollection<T> extends MapReduceWithQuery<T> {
+
+		/**
+		 * Explicitly set the name of the collection to perform the mapReduce operation on. <br />
+		 * Skip this step to use the default collection derived from the domain type.
+		 *
+		 * @param collection must not be {@literal null} nor {@literal empty}.
+		 * @return new instance of {@link MapReduceWithProjection}.
+		 * @throws IllegalArgumentException if collection is {@literal null}.
+		 */
+		MapReduceWithProjection<T> inCollection(String collection);
+	}
+
+	/**
+	 * Input document filter query (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithQuery<T> extends TerminatingMapReduce<T> {
+
+		/**
+		 * Set the filter query to be used.
+		 *
+		 * @param query must not be {@literal null}.
+		 * @return new instance of {@link TerminatingMapReduce}.
+		 * @throws IllegalArgumentException if query is {@literal null}.
+		 */
+		TerminatingMapReduce<T> matching(Query query);
+	}
+
+	/**
+	 * Result type override (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithProjection<T> extends MapReduceWithQuery<T> {
+
+		/**
+		 * Define the target type fields should be mapped to. <br />
+		 * Skip this step if you are anyway only interested in the original domain type.
+		 *
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link TerminatingMapReduce}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		<R> MapReduceWithQuery<R> as(Class<R> resultType);
+	}
+
+	/**
+	 * Additional mapReduce options (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithOptions<T> {
+
+		/**
+		 * Set additional options to apply to the mapReduce operation.
+		 *
+		 * @param options must not be {@literal null}.
+		 * @return new instance of {@link ExecutableMapReduce}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
+		 */
+		ExecutableMapReduce<T> with(MapReduceOptions options);
+	}
+
+	/**
+	 * {@link ExecutableMapReduce} provides methods for constructing mapReduce operations in a fluent way.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface ExecutableMapReduce<T> extends MapReduceWithMapFunction<T>, MapReduceWithReduceFunction<T>,
+			MapReduceWithCollection<T>, MapReduceWithProjection<T>, MapReduceWithOptions<T> {
+
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableMapReduceOperationSupport.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
+import java.util.List;
+
+import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Implementation of {@link ExecutableMapReduceOperation}.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+@RequiredArgsConstructor
+class ExecutableMapReduceOperationSupport implements ExecutableMapReduceOperation {
+
+	private static final Query ALL_QUERY = new Query();
+
+	private final @NonNull MongoTemplate template;
+
+	/*
+	 * (non-Javascript)
+	 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation#mapReduce(java.lang.Class)
+	 */
+	@Override
+	public <T> ExecutableMapReduceSupport<T> mapReduce(Class<T> domainType) {
+
+		Assert.notNull(domainType, "DomainType must not be null!");
+
+		return new ExecutableMapReduceSupport<>(template, domainType, domainType, null, ALL_QUERY, null, null, null);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	static class ExecutableMapReduceSupport<T>
+			implements ExecutableMapReduce<T>, MapReduceWithOptions<T>, MapReduceWithCollection<T>,
+			MapReduceWithProjection<T>, MapReduceWithQuery<T>, MapReduceWithReduceFunction<T>, MapReduceWithMapFunction<T> {
+
+		private final MongoTemplate template;
+		private final Class<?> domainType;
+		private final Class<T> returnType;
+		private final @Nullable String collection;
+		private final Query query;
+		private final @Nullable String mapFunction;
+		private final @Nullable String reduceFunction;
+		private final @Nullable MapReduceOptions options;
+
+		ExecutableMapReduceSupport(MongoTemplate template, Class<?> domainType, Class<T> returnType,
+				@Nullable String collection, Query query, @Nullable String mapFunction, @Nullable String reduceFunction,
+				@Nullable MapReduceOptions options) {
+
+			this.template = template;
+			this.domainType = domainType;
+			this.returnType = returnType;
+			this.collection = collection;
+			this.query = query;
+			this.mapFunction = mapFunction;
+			this.reduceFunction = reduceFunction;
+			this.options = options;
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.TerminatingMapReduce#all()
+		 */
+		@Override
+		public List<T> all() {
+			return template.mapReduce(query, domainType, getCollectionName(), mapFunction, reduceFunction, options,
+					returnType);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithCollection#inCollection(java.lang.String)
+		 */
+		@Override
+		public MapReduceWithProjection<T> inCollection(String collection) {
+
+			Assert.hasText(collection, "Collection name must not be null nor empty!");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithQuery#query(org.springframework.data.mongodb.core.query.Query)
+		 */
+		@Override
+		public TerminatingMapReduce<T> matching(Query query) {
+
+			Assert.notNull(query, "Query must not be null!");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithProjection#as(java.lang.Class)
+		 */
+		@Override
+		public <R> MapReduceWithQuery<R> as(Class<R> resultType) {
+
+			Assert.notNull(resultType, "ResultType must not be null!");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, resultType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithOptions#with(org.springframework.data.mongodb.core.mapreduce.MapReduceOptions)
+		 */
+		@Override
+		public ExecutableMapReduce<T> with(MapReduceOptions options) {
+
+			Assert.notNull(options, "Options must not be null! Please consider empty MapReduceOptions#options() instead.");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithMapFunction#map(java.lang.String)
+		 */
+		@Override
+		public MapReduceWithReduceFunction<T> map(String mapFunction) {
+
+			Assert.hasText(mapFunction, "MapFunction name must not be null nor empty!");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.MapReduceWithReduceFunction#reduce(java.lang.String)
+		 */
+		@Override
+		public ExecutableMapReduce<T> reduce(String reduceFunction) {
+
+			Assert.hasText(reduceFunction, "ReduceFunction name must not be null nor empty!");
+
+			return new ExecutableMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		private String getCollectionName() {
+			return StringUtils.hasText(collection) ? collection : template.getCollectionName(domainType);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableRemoveOperation.java

@@ -53,6 +53,37 @@ public interface ExecutableRemoveOperation {
 	 */
 	<T> ExecutableRemove<T> remove(Class<T> domainType);
 
+	/**
+	 * @author Christoph Strobl
+	 * @since 2.0
+	 */
+	interface TerminatingRemove<T> {
+
+		/**
+		 * Remove all documents matching.
+		 *
+		 * @return the {@link DeleteResult}. Never {@literal null}.
+		 */
+		DeleteResult all();
+
+		/**
+		 * Remove the first matching document.
+		 *
+		 * @return the {@link DeleteResult}. Never {@literal null}.
+		 */
+		DeleteResult one();
+
+		/**
+		 * Remove and return all matching documents. <br/>
+		 * <strong>NOTE</strong> The entire list of documents will be fetched before sending the actual delete commands.
+		 * Also, {@link org.springframework.context.ApplicationEvent}s will be published for each and every delete
+		 * operation.
+		 *
+		 * @return empty {@link List} if no match found. Never {@literal null}.
+		 */
+		List<T> findAndRemove();
+	}
+
 	/**
 	 * Collection override (optional).
 	 *
@@ -73,29 +104,6 @@ public interface ExecutableRemoveOperation {
 		RemoveWithQuery<T> inCollection(String collection);
 	}
 
-	/**
-	 * @author Christoph Strobl
-	 * @since 2.0
-	 */
-	interface TerminatingRemove<T> {
-
-		/**
-		 * Remove all documents matching.
-		 *
-		 * @return the {@link DeleteResult}. Never {@literal null}.
-		 */
-		DeleteResult all();
-
-		/**
-		 * Remove and return all matching documents. <br/>
-		 * <strong>NOTE</strong> The entire list of documents will be fetched before sending the actual delete commands.
-		 * Also, {@link org.springframework.context.ApplicationEvent}s will be published for each and every delete
-		 * operation.
-		 *
-		 * @return empty {@link List} if no match found. Never {@literal null}.
-		 */
-		List<T> findAndRemove();
-	}
 
 	/**
 	 * @author Christoph Strobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableRemoveOperationSupport.java

@@ -36,24 +36,12 @@ import com.mongodb.client.result.DeleteResult;
  * @author Mark Paluch
  * @since 2.0
  */
+@RequiredArgsConstructor
 class ExecutableRemoveOperationSupport implements ExecutableRemoveOperation {
 
 	private static final Query ALL_QUERY = new Query();
 
-	private final MongoTemplate tempate;
-
-	/**
-	 * Create new {@link ExecutableRemoveOperationSupport}.
-	 *
-	 * @param template must not be {@literal null}.
-	 * @throws IllegalArgumentException if template is {@literal null}.
-	 */
-	ExecutableRemoveOperationSupport(MongoTemplate template) {
-
-		Assert.notNull(template, "Template must not be null!");
-
-		this.tempate = template;
-	}
+	private final @NonNull MongoTemplate tempate;
 
 	/*
 	 * (non-Javadoc)
@@ -110,10 +98,16 @@ class ExecutableRemoveOperationSupport implements ExecutableRemoveOperation {
 		 */
 		@Override
 		public DeleteResult all() {
+			return template.doRemove(getCollectionName(), query, domainType, true);
+		}
 
-			String collectionName = getCollectionName();
-
-			return template.doRemove(collectionName, query, domainType);
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableRemoveOperation.TerminatingRemove#one()
+		 */
+		@Override
+		public DeleteResult one() {
+			return template.doRemove(getCollectionName(), query, domainType, false);
 		}
 
 		/*
@@ -129,7 +123,7 @@ class ExecutableRemoveOperationSupport implements ExecutableRemoveOperation {
 		}
 
 		private String getCollectionName() {
-			return StringUtils.hasText(collection) ? collection : template.determineCollectionName(domainType);
+			return StringUtils.hasText(collection) ? collection : template.getCollectionName(domainType);
 		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableUpdateOperation.java

@@ -19,13 +19,13 @@ import java.util.Optional;
 
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
-
-import com.mongodb.client.result.UpdateResult;
 import org.springframework.lang.Nullable;
 
+import com.mongodb.client.result.UpdateResult;
+
 /**
- * {@link ExecutableUpdateOperation} allows creation and execution of MongoDB update / findAndModify operations in a
- * fluent API style. <br />
+ * {@link ExecutableUpdateOperation} allows creation and execution of MongoDB update / findAndModify / findAndReplace
+ * operations in a fluent API style. <br />
  * The starting {@literal domainType} is used for mapping the {@link Query} provided via {@code matching}, as well as
  * the {@link Update} via {@code apply} into the MongoDB specific representations. The collection to operate on is by
  * default derived from the initial {@literal domainType} and can be defined there via
@@ -57,6 +57,91 @@ public interface ExecutableUpdateOperation {
 	 */
 	<T> ExecutableUpdate<T> update(Class<T> domainType);
 
+	/**
+	 * Trigger findAndModify execution by calling one of the terminating methods.
+	 *
+	 * @author Christoph Strobl
+	 * @author Mark Paluch
+	 * @since 2.0
+	 */
+	interface TerminatingFindAndModify<T> {
+
+		/**
+		 * Find, modify and return the first matching document.
+		 *
+		 * @return {@link Optional#empty()} if nothing found.
+		 */
+		default Optional<T> findAndModify() {
+			return Optional.ofNullable(findAndModifyValue());
+		}
+
+		/**
+		 * Find, modify and return the first matching document.
+		 *
+		 * @return {@literal null} if nothing found.
+		 */
+		@Nullable
+		T findAndModifyValue();
+	}
+
+	/**
+	 * Trigger
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * execution by calling one of the terminating methods.
+	 *
+	 * @author Mark Paluch
+	 * @since 2.1
+	 */
+	interface TerminatingFindAndReplace<T> {
+
+		/**
+		 * Find, replace and return the first matching document.
+		 *
+		 * @return {@link Optional#empty()} if nothing found.
+		 */
+		default Optional<T> findAndReplace() {
+			return Optional.ofNullable(findAndReplaceValue());
+		}
+
+		/**
+		 * Find, replace and return the first matching document.
+		 *
+		 * @return {@literal null} if nothing found.
+		 */
+		@Nullable
+		T findAndReplaceValue();
+	}
+
+	/**
+	 * Trigger update execution by calling one of the terminating methods.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.0
+	 */
+	interface TerminatingUpdate<T> extends TerminatingFindAndModify<T>, FindAndModifyWithOptions<T> {
+
+		/**
+		 * Update all matching documents in the collection.
+		 *
+		 * @return never {@literal null}.
+		 */
+		UpdateResult all();
+
+		/**
+		 * Update the first document in the collection.
+		 *
+		 * @return never {@literal null}.
+		 */
+		UpdateResult first();
+
+		/**
+		 * Creates a new document if no documents match the filter query or updates the matching ones.
+		 *
+		 * @return never {@literal null}.
+		 */
+		UpdateResult upsert();
+	}
+
 	/**
 	 * Declare the {@link Update} to apply.
 	 *
@@ -73,6 +158,16 @@ public interface ExecutableUpdateOperation {
 		 * @throws IllegalArgumentException if update is {@literal null}.
 		 */
 		TerminatingUpdate<T> apply(Update update);
+
+		/**
+		 * Specify {@code replacement} object.
+		 *
+		 * @param replacement must not be {@literal null}.
+		 * @return new instance of {@link FindAndReplaceOptions}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
+		 * @since 2.1
+		 */
+		FindAndReplaceWithProjection<T> replaceWith(T replacement);
 	}
 
 	/**
@@ -131,56 +226,43 @@ public interface ExecutableUpdateOperation {
 	}
 
 	/**
-	 * Trigger findAndModify execution by calling one of the terminating methods.
+	 * Define {@link FindAndReplaceOptions}.
+	 *
+	 * @author Mark Paluch
+	 * @author Christoph Strobl
+	 * @since 2.1
 	 */
-	interface TerminatingFindAndModify<T> {
+	interface FindAndReplaceWithOptions<T> extends TerminatingFindAndReplace<T> {
 
 		/**
-		 * Find, modify and return the first matching document.
+		 * Explicitly define {@link FindAndReplaceOptions} for the {@link Update}.
 		 *
-		 * @return {@link Optional#empty()} if nothing found.
+		 * @param options must not be {@literal null}.
+		 * @return new instance of {@link FindAndReplaceOptions}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
 		 */
-		default Optional<T> findAndModify() {
-			return Optional.ofNullable(findAndModifyValue());
-		}
-
-		/**
-		 * Find, modify and return the first matching document.
-		 *
-		 * @return {@literal null} if nothing found.
-		 */
-		@Nullable
-		T findAndModifyValue();
+		FindAndReplaceWithProjection<T> withOptions(FindAndReplaceOptions options);
 	}
 
 	/**
-	 * Trigger update execution by calling one of the terminating methods.
+	 * Result type override (Optional).
 	 *
 	 * @author Christoph Strobl
-	 * @since 2.0
+	 * @since 2.1
 	 */
-	interface TerminatingUpdate<T> extends TerminatingFindAndModify<T>, FindAndModifyWithOptions<T> {
+	interface FindAndReplaceWithProjection<T> extends FindAndReplaceWithOptions<T> {
 
 		/**
-		 * Update all matching documents in the collection.
+		 * Define the target type fields should be mapped to. <br />
+		 * Skip this step if you are anyway only interested in the original domain type.
 		 *
-		 * @return never {@literal null}.
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link FindAndReplaceWithProjection}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
 		 */
-		UpdateResult all();
+		<R> FindAndReplaceWithOptions<R> as(Class<R> resultType);
 
-		/**
-		 * Update the first document in the collection.
-		 *
-		 * @return never {@literal null}.
-		 */
-		UpdateResult first();
-
-		/**
-		 * Creates a new document if no documents match the filter query or updates the matching ones.
-		 *
-		 * @return never {@literal null}.
-		 */
-		UpdateResult upsert();
 	}
 
 	/**

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ExecutableUpdateOperationSupport.java

@@ -35,23 +35,12 @@ import com.mongodb.client.result.UpdateResult;
  * @author Mark Paluch
  * @since 2.0
  */
+@RequiredArgsConstructor
 class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 	private static final Query ALL_QUERY = new Query();
 
-	private final MongoTemplate template;
-
-	/**
-	 * Creates new {@link ExecutableUpdateOperationSupport}.
-	 *
-	 * @param template must not be {@literal null}.
-	 */
-	ExecutableUpdateOperationSupport(MongoTemplate template) {
-
-		Assert.notNull(template, "Template must not be null!");
-
-		this.template = template;
-	}
+	private final @NonNull MongoTemplate template;
 
 	/*
 	 * (non-Javadoc)
@@ -62,7 +51,7 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 		Assert.notNull(domainType, "DomainType must not be null!");
 
-		return new ExecutableUpdateSupport<>(template, domainType, ALL_QUERY, null, null, null);
+		return new ExecutableUpdateSupport<>(template, domainType, ALL_QUERY, null, null, null, null, null, domainType);
 	}
 
 	/**
@@ -72,14 +61,18 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 	@RequiredArgsConstructor
 	@FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
 	static class ExecutableUpdateSupport<T>
-			implements ExecutableUpdate<T>, UpdateWithCollection<T>, UpdateWithQuery<T>, TerminatingUpdate<T> {
+			implements ExecutableUpdate<T>, UpdateWithCollection<T>, UpdateWithQuery<T>, TerminatingUpdate<T>,
+			FindAndReplaceWithOptions<T>, TerminatingFindAndReplace<T>, FindAndReplaceWithProjection<T> {
 
 		@NonNull MongoTemplate template;
-		@NonNull Class<T> domainType;
+		@NonNull Class domainType;
 		Query query;
 		@Nullable Update update;
 		@Nullable String collection;
-		@Nullable FindAndModifyOptions options;
+		@Nullable FindAndModifyOptions findAndModifyOptions;
+		@Nullable FindAndReplaceOptions findAndReplaceOptions;
+		@Nullable Object replacement;
+		@NonNull Class<T> targetType;
 
 		/*
 		 * (non-Javadoc)
@@ -90,7 +83,8 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 			Assert.notNull(update, "Update must not be null!");
 
-			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
 		}
 
 		/*
@@ -102,7 +96,8 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 			Assert.hasText(collection, "Collection must not be null nor empty!");
 
-			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
 		}
 
 		/*
@@ -114,7 +109,34 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 			Assert.notNull(options, "Options must not be null!");
 
-			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, options,
+					findAndReplaceOptions, replacement, targetType);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableUpdateOperation.UpdateWithUpdate#replaceWith(Object)
+		 */
+		@Override
+		public FindAndReplaceWithProjection<T> replaceWith(T replacement) {
+
+			Assert.notNull(replacement, "Replacement must not be null!");
+
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableUpdateOperation.FindAndReplaceWithOptions#withOptions(org.springframework.data.mongodb.core.FindAndReplaceOptions)
+		 */
+		@Override
+		public FindAndReplaceWithProjection<T> withOptions(FindAndReplaceOptions options) {
+
+			Assert.notNull(options, "Options must not be null!");
+
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					options, replacement, targetType);
 		}
 
 		/*
@@ -126,7 +148,21 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 
 			Assert.notNull(query, "Query must not be null!");
 
-			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveUpdateOperation.FindAndReplaceWithProjection#as(java.lang.Class)
+		 */
+		@Override
+		public <R> FindAndReplaceWithOptions<R> as(Class<R> resultType) {
+
+			Assert.notNull(resultType, "ResultType must not be null!");
+
+			return new ExecutableUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, resultType);
 		}
 
 		/*
@@ -162,7 +198,22 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 		 */
 		@Override
 		public @Nullable T findAndModifyValue() {
-			return template.findAndModify(query, update, options != null ? options : new FindAndModifyOptions(), domainType, getCollectionName());
+
+			return template.findAndModify(query, update,
+					findAndModifyOptions != null ? findAndModifyOptions : new FindAndModifyOptions(), targetType,
+					getCollectionName());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ExecutableUpdateOperation.TerminatingFindAndReplace#findAndReplaceValue()
+		 */
+		@Override
+		public @Nullable T findAndReplaceValue() {
+
+			return (T) template.findAndReplace(query, replacement,
+					findAndReplaceOptions != null ? findAndReplaceOptions : FindAndReplaceOptions.empty(), domainType,
+					getCollectionName(), targetType);
 		}
 
 		private UpdateResult doUpdate(boolean multi, boolean upsert) {
@@ -170,7 +221,7 @@ class ExecutableUpdateOperationSupport implements ExecutableUpdateOperation {
 		}
 
 		private String getCollectionName() {
-			return StringUtils.hasText(collection) ? collection : template.determineCollectionName(domainType);
+			return StringUtils.hasText(collection) ? collection : template.getCollectionName(domainType);
 		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/FindAndModifyOptions.java

@@ -36,15 +36,17 @@ public class FindAndModifyOptions {
 	/**
 	 * Static factory method to create a FindAndModifyOptions instance
 	 *
-	 * @return a new instance
+	 * @return new instance of {@link FindAndModifyOptions}.
 	 */
 	public static FindAndModifyOptions options() {
 		return new FindAndModifyOptions();
 	}
 
 	/**
-	 * @param options
-	 * @return
+	 * Create new {@link FindAndModifyOptions} based on option of given {@litearl source}.
+	 * 
+	 * @param source can be {@literal null}.
+	 * @return new instance of {@link FindAndModifyOptions}.
 	 * @since 2.0
 	 */
 	public static FindAndModifyOptions of(@Nullable FindAndModifyOptions source) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/FindAndReplaceOptions.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+/**
+ * Options for
+ * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>.
+ * <br />
+ * Defaults to
+ * <dl>
+ * <dt>returnNew</dt>
+ * <dd>false</dd>
+ * <dt>upsert</dt>
+ * <dd>false</dd>
+ * </dl>
+ *
+ * @author Mark Paluch
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public class FindAndReplaceOptions {
+
+	private boolean returnNew;
+	private boolean upsert;
+
+	/**
+	 * Static factory method to create a {@link FindAndReplaceOptions} instance.
+	 * <dl>
+	 * <dt>returnNew</dt>
+	 * <dd>false</dd>
+	 * <dt>upsert</dt>
+	 * <dd>false</dd>
+	 * </dl>
+	 *
+	 * @return new instance of {@link FindAndReplaceOptions}.
+	 */
+	public static FindAndReplaceOptions options() {
+		return new FindAndReplaceOptions();
+	}
+
+	/**
+	 * Static factory method to create a {@link FindAndReplaceOptions} instance with
+	 * <dl>
+	 * <dt>returnNew</dt>
+	 * <dd>false</dd>
+	 * <dt>upsert</dt>
+	 * <dd>false</dd>
+	 * </dl>
+	 *
+	 * @return new instance of {@link FindAndReplaceOptions}.
+	 */
+	public static FindAndReplaceOptions empty() {
+		return new FindAndReplaceOptions();
+	}
+
+	/**
+	 * Return the replacement document.
+	 *
+	 * @return this.
+	 */
+	public FindAndReplaceOptions returnNew() {
+
+		this.returnNew = true;
+		return this;
+	}
+
+	/**
+	 * Insert a new document if not exists.
+	 *
+	 * @return this.
+	 */
+	public FindAndReplaceOptions upsert() {
+
+		this.upsert = true;
+		return this;
+	}
+
+	/**
+	 * Get the bit indicating to return the replacement document.
+	 *
+	 * @return
+	 */
+	public boolean isReturnNew() {
+		return returnNew;
+	}
+
+	/**
+	 * Get the bit indicating if to create a new document if not exists.
+	 *
+	 * @return
+	 */
+	public boolean isUpsert() {
+		return upsert;
+	}
+
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/FluentMongoOperations.java

@@ -22,4 +22,4 @@ package org.springframework.data.mongodb.core;
  * @since 2.0
  */
 public interface FluentMongoOperations extends ExecutableFindOperation, ExecutableInsertOperation,
-		ExecutableUpdateOperation, ExecutableRemoveOperation, ExecutableAggregationOperation {}
+		ExecutableUpdateOperation, ExecutableRemoveOperation, ExecutableAggregationOperation, ExecutableMapReduceOperation {}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/GeoCommandStatistics.java

@@ -20,7 +20,7 @@ import org.springframework.util.Assert;
 
 /**
  * Value object to mitigate different representations of geo command execution results in MongoDB.
- * 
+ *
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @soundtrack Fruitcake - Jeff Coffin (The Inside of the Outside)
@@ -34,7 +34,7 @@ class GeoCommandStatistics {
 
 	/**
 	 * Creates a new {@link GeoCommandStatistics} instance with the given source document.
-	 * 
+	 *
 	 * @param source must not be {@literal null}.
 	 */
 	private GeoCommandStatistics(Document source) {
@@ -45,7 +45,7 @@ class GeoCommandStatistics {
 
 	/**
 	 * Creates a new {@link GeoCommandStatistics} from the given command result extracting the statistics.
-	 * 
+	 *
 	 * @param commandResult must not be {@literal null}.
 	 * @return
 	 */
@@ -60,7 +60,7 @@ class GeoCommandStatistics {
 	/**
 	 * Returns the average distance reported by the command result. Mitigating a removal of the field in case the command
 	 * didn't return any result introduced in MongoDB 3.2 RC1.
-	 * 
+	 *
 	 * @return
 	 * @see <a href="https://jira.mongodb.org/browse/SERVER-21024">MongoDB Jira SERVER-21024</a>
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MappedDocument.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.bson.Document;
+import org.bson.conversions.Bson;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.data.mongodb.core.query.UpdateDefinition;
+import org.springframework.data.util.StreamUtils;
+
+import com.mongodb.client.model.Filters;
+
+/**
+ * A MongoDB document in its mapped state. I.e. after a source document has been mapped using mapping information of the
+ * entity the source document was supposed to represent.
+ *
+ * @author Oliver Gierke
+ * @since 2.1
+ */
+@RequiredArgsConstructor(staticName = "of")
+public class MappedDocument {
+
+	private static final String ID_FIELD = "_id";
+	private static final Document ID_ONLY_PROJECTION = new Document(ID_FIELD, 1);
+
+	private final @Getter Document document;
+
+	public static Document getIdOnlyProjection() {
+		return ID_ONLY_PROJECTION;
+	}
+
+	public static Document getIdIn(Collection<?> ids) {
+		return new Document(ID_FIELD, new Document("$in", ids));
+	}
+
+	public static List<Object> toIds(Collection<Document> documents) {
+
+		return documents.stream()//
+				.map(it -> it.get(ID_FIELD))//
+				.collect(StreamUtils.toUnmodifiableList());
+	}
+
+	public boolean hasId() {
+		return document.containsKey(ID_FIELD);
+	}
+
+	public boolean hasNonNullId() {
+		return hasId() && document.get(ID_FIELD) != null;
+	}
+
+	public Object getId() {
+		return document.get(ID_FIELD);
+	}
+
+	public <T> T getId(Class<T> type) {
+		return document.get(ID_FIELD, type);
+	}
+
+	public boolean isIdPresent(Class<?> type) {
+		return type.isInstance(getId());
+	}
+
+	public Bson getIdFilter() {
+		return Filters.eq(ID_FIELD, document.get(ID_FIELD));
+	}
+
+	public UpdateDefinition updateWithoutId() {
+		return new MappedUpdate(Update.fromDocument(document, ID_FIELD));
+	}
+
+	/**
+	 * An {@link UpdateDefinition} that indicates that the {@link #getUpdateObject() update object} has already been
+	 * mapped to the specific domain type.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1.4
+	 */
+	class MappedUpdate implements UpdateDefinition {
+
+		private final Update delegate;
+
+		MappedUpdate(Update delegate) {
+			this.delegate = delegate;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.query.UpdateDefinition#getUpdateObject()
+		 */
+		@Override
+		public Document getUpdateObject() {
+			return delegate.getUpdateObject();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.query.UpdateDefinition#modifies(java.lang.String)
+		 */
+		@Override
+		public boolean modifies(String key) {
+			return delegate.modifies(key);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.query.UpdateDefinition#inc(java.lang.String)
+		 */
+		@Override
+		public void inc(String version) {
+			delegate.inc(version);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.query.UpdateDefinition#isIsolated()
+		 */
+		@Override
+		public Boolean isIsolated() {
+			return delegate.isIsolated();
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoAction.java

@@ -29,7 +29,7 @@ import com.mongodb.WriteConcern;
  * <li>REMOVE has null document</li>
  * <li>INSERT_LIST has null entityType, document, and query</li>
  * </ul>
- * 
+ *
  * @author Mark Pollack
  * @author Oliver Gierke
  * @author Christoph Strobl
@@ -46,7 +46,7 @@ public class MongoAction {
 
 	/**
 	 * Create an instance of a {@link MongoAction}.
-	 * 
+	 *
 	 * @param defaultWriteConcern the default write concern. Can be {@literal null}.
 	 * @param mongoActionOperation action being taken against the collection. Must not be {@literal null}.
 	 * @param collectionName the collection name, must not be {@literal null} or empty.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoActionOperation.java

@@ -18,7 +18,7 @@ package org.springframework.data.mongodb.core;
 /**
  * Enumeration for operations on a collection. Used with {@link MongoAction} to help determine the WriteConcern to use
  * for a given mutating operation
- * 
+ *
  * @author Mark Pollack
  * @author Oliver Gierke
  * @see MongoAction

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoAdmin.java

@@ -25,7 +25,7 @@ import com.mongodb.client.MongoDatabase;
 
 /**
  * Mongo server administration exposed via JMX annotations
- * 
+ *
  * @author Mark Pollack
  * @author Thomas Darimont
  * @author Mark Paluch

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoDataIntegrityViolationException.java

@@ -23,7 +23,7 @@ import com.mongodb.WriteResult;
 
 /**
  * Mongo-specific {@link DataIntegrityViolationException}.
- * 
+ *
  * @author Oliver Gierke
  */
 public class MongoDataIntegrityViolationException extends DataIntegrityViolationException {
@@ -35,7 +35,7 @@ public class MongoDataIntegrityViolationException extends DataIntegrityViolation
 
 	/**
 	 * Creates a new {@link MongoDataIntegrityViolationException} using the given message and {@link WriteResult}.
-	 * 
+	 *
 	 * @param message the exception message
 	 * @param writeResult the {@link WriteResult} that causes the exception, must not be {@literal null}.
 	 * @param actionOperation the {@link MongoActionOperation} that caused the exception, must not be {@literal null}.
@@ -54,7 +54,7 @@ public class MongoDataIntegrityViolationException extends DataIntegrityViolation
 
 	/**
 	 * Returns the {@link WriteResult} that caused the exception.
-	 * 
+	 *
 	 * @return the writeResult
 	 */
 	public WriteResult getWriteResult() {
@@ -63,7 +63,7 @@ public class MongoDataIntegrityViolationException extends DataIntegrityViolation
 
 	/**
 	 * Returns the {@link MongoActionOperation} in which the current exception occured.
-	 * 
+	 *
 	 * @return the actionOperation
 	 */
 	public MongoActionOperation getActionOperation() {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoDbFactorySupport.java

@@ -0,0 +1,272 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.Value;
+
+import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.dao.DataAccessException;
+import org.springframework.dao.support.PersistenceExceptionTranslator;
+import org.springframework.data.mongodb.MongoDbFactory;
+import org.springframework.data.mongodb.SessionAwareMethodInterceptor;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.DB;
+import com.mongodb.WriteConcern;
+import com.mongodb.client.ClientSession;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+
+/**
+ * Common base class for usage with both {@link com.mongodb.client.MongoClients} and {@link com.mongodb.MongoClient}
+ * defining common properties such as database name and exception translator.
+ * <p/>
+ * Not intended to be used directly.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @param <C> Client type.
+ * @since 2.1
+ * @see SimpleMongoDbFactory
+ * @see SimpleMongoClientDbFactory
+ */
+public abstract class MongoDbFactorySupport<C> implements MongoDbFactory {
+
+	private final C mongoClient;
+	private final String databaseName;
+	private final boolean mongoInstanceCreated;
+	private final PersistenceExceptionTranslator exceptionTranslator;
+
+	private @Nullable WriteConcern writeConcern;
+
+	/**
+	 * Create a new {@link MongoDbFactorySupport} object given {@code mongoClient}, {@code databaseName},
+	 * {@code mongoInstanceCreated} and {@link PersistenceExceptionTranslator}.
+	 * 
+	 * @param mongoClient must not be {@literal null}.
+	 * @param databaseName must not be {@literal null} or empty.
+	 * @param mongoInstanceCreated {@literal true} if the client instance was created by a subclass of
+	 *          {@link MongoDbFactorySupport} to close the client on {@link #destroy()}.
+	 * @param exceptionTranslator must not be {@literal null}.
+	 */
+	protected MongoDbFactorySupport(C mongoClient, String databaseName, boolean mongoInstanceCreated,
+			PersistenceExceptionTranslator exceptionTranslator) {
+
+		Assert.notNull(mongoClient, "MongoClient must not be null!");
+		Assert.hasText(databaseName, "Database name must not be empty!");
+		Assert.isTrue(databaseName.matches("[^/\\\\.$\"\\s]+"),
+				"Database name must not contain slashes, dots, spaces, quotes, or dollar signs!");
+
+		this.mongoClient = mongoClient;
+		this.databaseName = databaseName;
+		this.mongoInstanceCreated = mongoInstanceCreated;
+		this.exceptionTranslator = exceptionTranslator;
+	}
+
+	/**
+	 * Configures the {@link WriteConcern} to be used on the {@link MongoDatabase} instance being created.
+	 *
+	 * @param writeConcern the writeConcern to set
+	 */
+	public void setWriteConcern(WriteConcern writeConcern) {
+		this.writeConcern = writeConcern;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb()
+	 */
+	public MongoDatabase getDb() throws DataAccessException {
+		return getDb(databaseName);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb(java.lang.String)
+	 */
+	@Override
+	public MongoDatabase getDb(String dbName) throws DataAccessException {
+
+		Assert.hasText(dbName, "Database name must not be empty!");
+
+		MongoDatabase db = doGetMongoDatabase(dbName);
+
+		if (writeConcern == null) {
+			return db;
+		}
+
+		return db.withWriteConcern(writeConcern);
+	}
+
+	/**
+	 * Get the actual {@link MongoDatabase} from the client.
+	 * 
+	 * @param dbName must not be {@literal null} or empty.
+	 * @return
+	 */
+	protected abstract MongoDatabase doGetMongoDatabase(String dbName);
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.beans.factory.DisposableBean#destroy()
+	 */
+	public void destroy() throws Exception {
+		if (mongoInstanceCreated) {
+			closeClient();
+		}
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getExceptionTranslator()
+	 */
+	public PersistenceExceptionTranslator getExceptionTranslator() {
+		return this.exceptionTranslator;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#withSession(com.mongodb.session.Session)
+	 */
+	public MongoDbFactory withSession(ClientSession session) {
+		return new MongoDbFactorySupport.ClientSessionBoundMongoDbFactory(session, this);
+	}
+
+	/**
+	 * Close the client instance.
+	 */
+	protected abstract void closeClient();
+
+	/**
+	 * @return the Mongo client object.
+	 */
+	protected C getMongoClient() {
+		return mongoClient;
+	}
+
+	/**
+	 * @return the database name.
+	 */
+	protected String getDefaultDatabaseName() {
+		return databaseName;
+	}
+
+	/**
+	 * {@link ClientSession} bound {@link MongoDbFactory} decorating the database with a
+	 * {@link SessionAwareMethodInterceptor}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	@Value
+	static class ClientSessionBoundMongoDbFactory implements MongoDbFactory {
+
+		ClientSession session;
+		MongoDbFactory delegate;
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#getDb()
+		 */
+		@Override
+		public MongoDatabase getDb() throws DataAccessException {
+			return proxyMongoDatabase(delegate.getDb());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#getDb(java.lang.String)
+		 */
+		@Override
+		public MongoDatabase getDb(String dbName) throws DataAccessException {
+			return proxyMongoDatabase(delegate.getDb(dbName));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#getExceptionTranslator()
+		 */
+		@Override
+		public PersistenceExceptionTranslator getExceptionTranslator() {
+			return delegate.getExceptionTranslator();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#getLegacyDb()
+		 */
+		@Override
+		public DB getLegacyDb() {
+			return delegate.getLegacyDb();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#getSession(com.mongodb.ClientSessionOptions)
+		 */
+		@Override
+		public ClientSession getSession(ClientSessionOptions options) {
+			return delegate.getSession(options);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#withSession(com.mongodb.session.ClientSession)
+		 */
+		@Override
+		public MongoDbFactory withSession(ClientSession session) {
+			return delegate.withSession(session);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.MongoDbFactory#isTransactionActive()
+		 */
+		@Override
+		public boolean isTransactionActive() {
+			return session != null && session.hasActiveTransaction();
+		}
+
+		private MongoDatabase proxyMongoDatabase(MongoDatabase database) {
+			return createProxyInstance(session, database, MongoDatabase.class);
+		}
+
+		private MongoDatabase proxyDatabase(com.mongodb.session.ClientSession session, MongoDatabase database) {
+			return createProxyInstance(session, database, MongoDatabase.class);
+		}
+
+		private MongoCollection<?> proxyCollection(com.mongodb.session.ClientSession session,
+				MongoCollection<?> collection) {
+			return createProxyInstance(session, collection, MongoCollection.class);
+		}
+
+		private <T> T createProxyInstance(com.mongodb.session.ClientSession session, T target, Class<T> targetType) {
+
+			ProxyFactory factory = new ProxyFactory();
+			factory.setTarget(target);
+			factory.setInterfaces(targetType);
+			factory.setOpaque(true);
+
+			factory.addAdvice(new SessionAwareMethodInterceptor<>(session, target, ClientSession.class, MongoDatabase.class,
+					this::proxyDatabase, MongoCollection.class, this::proxyCollection));
+
+			return targetType.cast(factory.getProxy());
+		}
+	}
+
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoExceptionTranslator.java

@@ -30,6 +30,8 @@ import org.springframework.dao.InvalidDataAccessResourceUsageException;
 import org.springframework.dao.PermissionDeniedDataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.BulkOperationException;
+import org.springframework.data.mongodb.ClientSessionException;
+import org.springframework.data.mongodb.MongoTransactionException;
 import org.springframework.data.mongodb.UncategorizedMongoDbException;
 import org.springframework.data.mongodb.util.MongoDbErrorCodes;
 import org.springframework.lang.Nullable;
@@ -45,7 +47,7 @@ import com.mongodb.bulk.BulkWriteError;
  * Simple {@link PersistenceExceptionTranslator} for Mongo. Convert the given runtime exception to an appropriate
  * exception from the {@code org.springframework.dao} hierarchy. Return {@literal null} if no translation is
  * appropriate: any other exception may have resulted from user code, and should not be translated.
- * 
+ *
  * @author Oliver Gierke
  * @author Michal Vich
  * @author Christoph Strobl
@@ -120,18 +122,32 @@ public class MongoExceptionTranslator implements PersistenceExceptionTranslator
 			int code = ((MongoException) ex).getCode();
 
 			if (MongoDbErrorCodes.isDuplicateKeyCode(code)) {
-				throw new DuplicateKeyException(ex.getMessage(), ex);
+				return new DuplicateKeyException(ex.getMessage(), ex);
 			} else if (MongoDbErrorCodes.isDataAccessResourceFailureCode(code)) {
-				throw new DataAccessResourceFailureException(ex.getMessage(), ex);
+				return new DataAccessResourceFailureException(ex.getMessage(), ex);
 			} else if (MongoDbErrorCodes.isInvalidDataAccessApiUsageCode(code) || code == 10003 || code == 12001
 					|| code == 12010 || code == 12011 || code == 12012) {
-				throw new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
+				return new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
 			} else if (MongoDbErrorCodes.isPermissionDeniedCode(code)) {
-				throw new PermissionDeniedDataAccessException(ex.getMessage(), ex);
+				return new PermissionDeniedDataAccessException(ex.getMessage(), ex);
+			} else if (MongoDbErrorCodes.isClientSessionFailureCode(code)) {
+				return new ClientSessionException(ex.getMessage(), ex);
+			} else if (MongoDbErrorCodes.isTransactionFailureCode(code)) {
+				return new MongoTransactionException(ex.getMessage(), ex);
 			}
 			return new UncategorizedMongoDbException(ex.getMessage(), ex);
 		}
 
+		// may interfere with OmitStackTraceInFastThrow (enabled by default).
+		// see https://jira.spring.io/browse/DATAMONGO-1905
+		if (ex instanceof IllegalStateException) {
+			for (StackTraceElement elm : ex.getStackTrace()) {
+				if (elm.getClassName().contains("ClientSession")) {
+					return new ClientSessionException(ex.getMessage(), ex);
+				}
+			}
+		}
+
 		// If we get here, we have an exception that resulted from user code,
 		// rather than the persistence provider, so we return null to indicate
 		// that translation should not occur.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoOperations.java

@@ -18,6 +18,8 @@ package org.springframework.data.mongodb.core;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
 
 import org.bson.Document;
 import org.springframework.data.geo.GeoResults;
@@ -26,6 +28,7 @@ import org.springframework.data.mongodb.core.aggregation.Aggregation;
 import org.springframework.data.mongodb.core.aggregation.AggregationOptions;
 import org.springframework.data.mongodb.core.aggregation.AggregationResults;
 import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
+import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
 import org.springframework.data.mongodb.core.index.IndexOperations;
 import org.springframework.data.mongodb.core.mapreduce.GroupBy;
@@ -39,9 +42,13 @@ import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.data.util.CloseableIterator;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
+import com.mongodb.ClientSessionOptions;
 import com.mongodb.Cursor;
 import com.mongodb.ReadPreference;
+import com.mongodb.client.ClientSession;
 import com.mongodb.client.MongoCollection;
 import com.mongodb.client.result.DeleteResult;
 import com.mongodb.client.result.UpdateResult;
@@ -151,6 +158,64 @@ public interface MongoOperations extends FluentMongoOperations {
 	@Nullable
 	<T> T execute(String collectionName, CollectionCallback<T> action);
 
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link SessionScoped} binding a new {@link ClientSession}
+	 * with given {@literal sessionOptions} to each and every command issued against MongoDB.
+	 *
+	 * @param sessionOptions must not be {@literal null}.
+	 * @return new instance of {@link SessionScoped}. Never {@literal null}.
+	 * @since 2.1
+	 */
+	SessionScoped withSession(ClientSessionOptions sessionOptions);
+
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link SessionScoped} binding the {@link ClientSession}
+	 * provided by the given {@link Supplier} to each and every command issued against MongoDB.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle. Use the
+	 * {@link SessionScoped#execute(SessionCallback, Consumer)} hook to potentially close the {@link ClientSession}.
+	 *
+	 * @param sessionProvider must not be {@literal null}.
+	 * @since 2.1
+	 */
+	default SessionScoped withSession(Supplier<ClientSession> sessionProvider) {
+
+		Assert.notNull(sessionProvider, "SessionProvider must not be null!");
+
+		return new SessionScoped() {
+
+			private final Object lock = new Object();
+			private @Nullable ClientSession session = null;
+
+			@Override
+			public <T> T execute(SessionCallback<T> action, Consumer<ClientSession> onComplete) {
+
+				synchronized (lock) {
+					if (session == null) {
+						session = sessionProvider.get();
+					}
+				}
+
+				try {
+					return action.doInSession(MongoOperations.this.withSession(session));
+				} finally {
+					onComplete.accept(session);
+				}
+			}
+		};
+	}
+
+	/**
+	 * Obtain a {@link ClientSession} bound instance of {@link MongoOperations}.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle.
+	 *
+	 * @param session must not be {@literal null}.
+	 * @return {@link ClientSession} bound instance of {@link MongoOperations}.
+	 * @since 2.1
+	 */
+	MongoOperations withSession(ClientSession session);
+
 	/**
 	 * Executes the given {@link Query} on the entity collection of the specified {@code entityType} backed by a Mongo DB
 	 * {@link Cursor}.
@@ -318,7 +383,7 @@ public interface MongoOperations extends FluentMongoOperations {
 	 * Returns a new {@link BulkOperations} for the given entity type and collection name.
 	 *
 	 * @param mode the {@link BulkMode} to use for bulk operations, must not be {@literal null}.
-	 * @param entityClass the name of the entity class. Can be {@literal null}.
+	 * @param entityType the name of the entity class. Can be {@literal null}.
 	 * @param collectionName the name of the collection to work on, must not be {@literal null} or empty.
 	 * @return {@link BulkOperations} on the named collection associated with the given entity class.
 	 */
@@ -357,8 +422,6 @@ public interface MongoOperations extends FluentMongoOperations {
 	 * Execute a group operation over the entire collection. The group operation entity class should match the 'shape' of
 	 * the returned object that takes int account the initial document structure as well as any finalize functions.
 	 *
-	 * @param criteria The criteria that restricts the row that are considered for grouping. If not specified all rows are
-	 *          considered.
 	 * @param inputCollectionName the collection where the group operation will read from
 	 * @param groupBy the conditions under which the group operation will be performed, e.g. keys, initial document,
 	 *          reduce function.
@@ -710,8 +773,67 @@ public interface MongoOperations extends FluentMongoOperations {
 	<T> T findById(Object id, Class<T> entityClass, String collectionName);
 
 	/**
-	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify
-	 * <a/> to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link List}.
+	 *
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param entityClass the domain type used for determining the actual {@link MongoCollection}. Must not be
+	 *          {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default <T> List<T> findDistinct(String field, Class<?> entityClass, Class<T> resultClass) {
+		return findDistinct(new Query(), field, entityClass, resultClass);
+	}
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link List}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param entityClass the domain type used for determining the actual {@link MongoCollection} and mapping the
+	 *          {@link Query} to the domain type fields. Must not be {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> List<T> findDistinct(Query query, String field, Class<?> entityClass, Class<T> resultClass);
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link List}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param collectionName the explicit name of the actual {@link MongoCollection}. Must not be {@literal null}.
+	 * @param entityClass the domain type used for mapping the {@link Query} to the domain type fields.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> List<T> findDistinct(Query query, String field, String collectionName, Class<?> entityClass,
+			Class<T> resultClass);
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link List}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param collection the explicit name of the actual {@link MongoCollection}. Must not be {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default <T> List<T> findDistinct(Query query, String field, String collection, Class<T> resultClass) {
+		return findDistinct(query, field, collection, Object.class, resultClass);
+	}
+
+	/**
+	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
+	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
 	 *
 	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
 	 *          fields specification. Must not be {@literal null}.
@@ -723,8 +845,8 @@ public interface MongoOperations extends FluentMongoOperations {
 	<T> T findAndModify(Query query, Update update, Class<T> entityClass);
 
 	/**
-	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify
-	 * <a/> to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
+	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
+	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query}.
 	 *
 	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
 	 *          fields specification. Must not be {@literal null}.
@@ -737,8 +859,8 @@ public interface MongoOperations extends FluentMongoOperations {
 	<T> T findAndModify(Query query, Update update, Class<T> entityClass, String collectionName);
 
 	/**
-	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify
-	 * <a/> to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
+	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
+	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
 	 * {@link FindAndModifyOptions} into account.
 	 *
 	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
@@ -754,8 +876,8 @@ public interface MongoOperations extends FluentMongoOperations {
 	<T> T findAndModify(Query query, Update update, FindAndModifyOptions options, Class<T> entityClass);
 
 	/**
-	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify
-	 * <a/> to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
+	 * Triggers <a href="https://docs.mongodb.org/manual/reference/method/db.collection.findAndModify/">findAndModify <a/>
+	 * to apply provided {@link Update} on documents matching {@link Criteria} of given {@link Query} taking
 	 * {@link FindAndModifyOptions} into account.
 	 *
 	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
@@ -772,6 +894,167 @@ public interface MongoOperations extends FluentMongoOperations {
 	<T> T findAndModify(Query query, Update update, FindAndModifyOptions options, Class<T> entityClass,
 			String collectionName);
 
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement}
+	 * document. <br />
+	 * The collection name is derived from the {@literal replacement} type. <br />
+	 * Options are defaulted to {@link FindAndReplaceOptions#empty()}. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@literal null}, if not found.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <T> T findAndReplace(Query query, T replacement) {
+		return findAndReplace(query, replacement, FindAndReplaceOptions.empty());
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement}
+	 * document.<br />
+	 * Options are defaulted to {@link FindAndReplaceOptions#empty()}. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@literal null}, if not found.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <T> T findAndReplace(Query query, T replacement, String collectionName) {
+		return findAndReplace(query, replacement, FindAndReplaceOptions.empty(), collectionName);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account.<br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@literal null}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <T> T findAndReplace(Query query, T replacement, FindAndReplaceOptions options) {
+		return findAndReplace(query, replacement, options, getCollectionName(ClassUtils.getUserClass(replacement)));
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account.<br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@literal null}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <T> T findAndReplace(Query query, T replacement, FindAndReplaceOptions options, String collectionName) {
+
+		Assert.notNull(replacement, "Replacement must not be null!");
+		return findAndReplace(query, replacement, options, (Class<T>) ClassUtils.getUserClass(replacement), collectionName);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account.<br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the parametrized type. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@literal null}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <T> T findAndReplace(Query query, T replacement, FindAndReplaceOptions options, Class<T> entityType,
+			String collectionName) {
+
+		return findAndReplace(query, replacement, options, entityType, collectionName, entityType);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account.<br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the type used for mapping the {@link Query} to domain type fields and deriving the collection
+	 *          from. Must not be {@literal null}.
+	 * @param resultType the parametrized type projection return type. Must not be {@literal null}, use the domain type of
+	 *          {@code Object.class} instead.
+	 * @return the converted object that was updated or {@literal null}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	@Nullable
+	default <S, T> T findAndReplace(Query query, S replacement, FindAndReplaceOptions options, Class<S> entityType,
+			Class<T> resultType) {
+
+		return findAndReplace(query, replacement, options, entityType,
+				getCollectionName(ClassUtils.getUserClass(entityType)), resultType);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account.<br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the type used for mapping the {@link Query} to domain type fields. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @param resultType the parametrized type projection return type. Must not be {@literal null}, use the domain type of
+	 *          {@code Object.class} instead.
+	 * @return the converted object that was updated or {@literal null}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	@Nullable
+	<S, T> T findAndReplace(Query query, S replacement, FindAndReplaceOptions options, Class<S> entityType,
+			String collectionName, Class<T> resultType);
+
 	/**
 	 * Map the results of an ad-hoc query on the collection for the entity type to a single instance of an object of the
 	 * specified type. The first document that matches the query is returned and also removed from the collection in the
@@ -858,8 +1141,9 @@ public interface MongoOperations extends FluentMongoOperations {
 	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
+	 * @return the inserted object.
 	 */
-	void insert(Object objectToSave);
+	<T> T insert(T objectToSave);
 
 	/**
 	 * Insert the object into the specified collection.
@@ -871,32 +1155,36 @@ public interface MongoOperations extends FluentMongoOperations {
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
+	 * @return the inserted object.
 	 */
-	void insert(Object objectToSave, String collectionName);
+	<T> T insert(T objectToSave, String collectionName);
 
 	/**
 	 * Insert a Collection of objects into a collection in a single batch write to the database.
 	 *
 	 * @param batchToSave the batch of objects to save. Must not be {@literal null}.
 	 * @param entityClass class that determines the collection to use. Must not be {@literal null}.
+	 * @return the inserted objects that.
 	 */
-	void insert(Collection<? extends Object> batchToSave, Class<?> entityClass);
+	<T> Collection<T> insert(Collection<? extends T> batchToSave, Class<?> entityClass);
 
 	/**
 	 * Insert a batch of objects into the specified collection in a single batch write to the database.
 	 *
 	 * @param batchToSave the list of objects to save. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
+	 * @return the inserted objects that.
 	 */
-	void insert(Collection<? extends Object> batchToSave, String collectionName);
+	<T> Collection<T> insert(Collection<? extends T> batchToSave, String collectionName);
 
 	/**
 	 * Insert a mixed Collection of objects into a database collection determining the collection name to use based on the
 	 * class.
 	 *
 	 * @param objectsToSave the list of objects to save. Must not be {@literal null}.
+	 * @return the inserted objects.
 	 */
-	void insertAll(Collection<? extends Object> objectsToSave);
+	<T> Collection<T> insertAll(Collection<? extends T> objectsToSave);
 
 	/**
 	 * Save the object to the collection for the entity type of the object to save. This will perform an insert if the
@@ -912,8 +1200,9 @@ public interface MongoOperations extends FluentMongoOperations {
 	 * Conversion"</a> for more details.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
+	 * @return the saved object.
 	 */
-	void save(Object objectToSave);
+	<T> T save(T objectToSave);
 
 	/**
 	 * Save the object to the specified collection. This will perform an insert if the object is not already present, that
@@ -930,8 +1219,9 @@ public interface MongoOperations extends FluentMongoOperations {
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
+	 * @return the saved object.
 	 */
-	void save(Object objectToSave, String collectionName);
+	<T> T save(T objectToSave, String collectionName);
 
 	/**
 	 * Performs an upsert. If no document is found that matches the query, a new document is created and inserted by

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/PropertyOperations.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.AccessLevel;
+import lombok.RequiredArgsConstructor;
+
+import org.bson.Document;
+import org.springframework.data.mapping.SimplePropertyHandler;
+import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.data.projection.ProjectionFactory;
+import org.springframework.data.projection.ProjectionInformation;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Common operations performed on properties of an entity like extracting fields information for projection creation.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+@RequiredArgsConstructor(access = AccessLevel.PACKAGE)
+class PropertyOperations {
+
+	private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
+
+	/**
+	 * For cases where {@code fields} is {@link Document#isEmpty() empty} include only fields that are required for
+	 * creating the projection (target) type if the {@code targetType} is a {@literal DTO projection} or a
+	 * {@literal closed interface projection}.
+	 *
+	 * @param projectionFactory must not be {@literal null}.
+	 * @param fields must not be {@literal null}.
+	 * @param domainType must not be {@literal null}.
+	 * @param targetType must not be {@literal null}.
+	 * @return {@link Document} with fields to be included.
+	 */
+	Document computeFieldsForProjection(ProjectionFactory projectionFactory, Document fields, Class<?> domainType,
+			Class<?> targetType) {
+
+		if (!fields.isEmpty() || ClassUtils.isAssignable(domainType, targetType)) {
+			return fields;
+		}
+
+		Document projectedFields = new Document();
+
+		if (targetType.isInterface()) {
+
+			ProjectionInformation projectionInformation = projectionFactory.getProjectionInformation(targetType);
+
+			if (projectionInformation.isClosed()) {
+				projectionInformation.getInputProperties().forEach(it -> projectedFields.append(it.getName(), 1));
+			}
+		} else {
+			mappingContext.getRequiredPersistentEntity(targetType).doWithProperties(
+					(SimplePropertyHandler) persistentProperty -> projectedFields.append(persistentProperty.getName(), 1));
+		}
+
+		return projectedFields;
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveCollectionCallback.java

@@ -30,5 +30,4 @@ import com.mongodb.reactivestreams.client.MongoCollection;
 public interface ReactiveCollectionCallback<T> {
 
 	Publisher<T> doInCollection(MongoCollection<Document> collection) throws MongoException, DataAccessException;
-
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveFindOperation.java

@@ -85,6 +85,23 @@ public interface ReactiveFindOperation {
 		 */
 		Flux<T> all();
 
+		/**
+		 * Get all matching elements using a {@link com.mongodb.CursorType#TailableAwait tailable cursor}. The stream will
+		 * not be completed unless the {@link org.reactivestreams.Subscription} is
+		 * {@link org.reactivestreams.Subscription#cancel() canceled}.
+		 * <p />
+		 * However, the stream may become dead, or invalid, if either the query returns no match or the cursor returns the
+		 * document at the "end" of the collection and then the application deletes that document.
+		 * <p />
+		 * A stream that is no longer in use must be {@link reactor.core.Disposable#dispose()} disposed} otherwise the
+		 * streams will linger and exhaust resources. <br/>
+		 * <strong>NOTE:</strong> Requires a capped collection.
+		 *
+		 * @return the {@link Flux} emitting converted objects.
+		 * @since 2.1
+		 */
+		Flux<T> tail();
+
 		/**
 		 * Get the number of matching elements.
 		 *
@@ -156,7 +173,7 @@ public interface ReactiveFindOperation {
 	/**
 	 * Result type override (optional).
 	 */
-	interface FindWithProjection<T> extends FindWithQuery<T> {
+	interface FindWithProjection<T> extends FindWithQuery<T>, FindDistinct {
 
 		/**
 		 * Define the target type fields should be mapped to. <br />
@@ -170,8 +187,101 @@ public interface ReactiveFindOperation {
 		<R> FindWithQuery<R> as(Class<R> resultType);
 	}
 
+	/**
+	 * Distinct Find support.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface FindDistinct {
+
+		/**
+		 * Finds the distinct values for a specified {@literal field} across a single
+		 * {@link com.mongodb.reactivestreams.client.MongoCollection} or view.
+		 *
+		 * @param field name of the field. Must not be {@literal null}.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if field is {@literal null}.
+		 */
+		TerminatingDistinct<Object> distinct(String field);
+	}
+
+	/**
+	 * Result type override. Optional.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface DistinctWithProjection {
+
+		/**
+		 * Define the target type the result should be mapped to. <br />
+		 * Skip this step if you are anyway fine with the default conversion.
+		 * <dl>
+		 * <dt>{@link Object} (the default)</dt>
+		 * <dd>Result is mapped according to the {@link org.bson.BsonType} converting eg. {@link org.bson.BsonString} into
+		 * plain {@link String}, {@link org.bson.BsonInt64} to {@link Long}, etc. always picking the most concrete type with
+		 * respect to the domain types property.<br />
+		 * Any {@link org.bson.BsonType#DOCUMENT} is run through the {@link org.springframework.data.convert.EntityReader}
+		 * to obtain the domain type. <br />
+		 * Using {@link Object} also works for non strictly typed fields. Eg. a mixture different types like fields using
+		 * {@link String} in one {@link org.bson.Document} while {@link Long} in another.</dd>
+		 * <dt>Any Simple type like {@link String}, {@link Long}, ...</dt>
+		 * <dd>The result is mapped directly by the MongoDB Java driver and the {@link org.bson.codecs.CodeCodec Codecs} in
+		 * place. This works only for results where all documents considered for the operation use the very same type for
+		 * the field.</dd>
+		 * <dt>Any Domain type</dt>
+		 * <dd>Domain types can only be mapped if the if the result of the actual {@code distinct()} operation returns
+		 * {@link org.bson.BsonType#DOCUMENT}.</dd>
+		 * <dt>{@link org.bson.BsonValue}</dt>
+		 * <dd>Using {@link org.bson.BsonValue} allows retrieval of the raw driver specific format, which returns eg.
+		 * {@link org.bson.BsonString}.</dd>
+		 * </dl>
+		 *
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		<R> TerminatingDistinct<R> as(Class<R> resultType);
+	}
+
+	/**
+	 * Result restrictions. Optional.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface DistinctWithQuery<T> extends DistinctWithProjection {
+
+		/**
+		 * Set the filter query to be used.
+		 *
+		 * @param query must not be {@literal null}.
+		 * @return new instance of {@link TerminatingDistinct}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		TerminatingDistinct<T> matching(Query query);
+	}
+
+	/**
+	 * Terminating distinct find operations.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface TerminatingDistinct<T> extends DistinctWithQuery<T> {
+
+		/**
+		 * Get all matching distinct field values.
+		 *
+		 * @return empty {@link Flux} if not match found. Never {@literal null}.
+		 */
+		Flux<T> all();
+	}
+
 	/**
 	 * {@link ReactiveFind} provides methods for constructing lookup operations in a fluent way.
 	 */
-	interface ReactiveFind<T> extends FindWithCollection<T>, FindWithProjection<T> {}
+	interface ReactiveFind<T> extends FindWithCollection<T>, FindWithProjection<T>, FindDistinct {}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveFindOperationSupport.java

@@ -19,7 +19,6 @@ import lombok.AccessLevel;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.experimental.FieldDefaults;
-import org.springframework.lang.Nullable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -28,6 +27,7 @@ import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.SerializationUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -169,6 +169,15 @@ class ReactiveFindOperationSupport implements ReactiveFindOperation {
 			return doFind(null);
 		}
 
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveFindOperation.TerminatingFind#tail()
+		 */
+		@Override
+		public Flux<T> tail() {
+			return doFind(template.new TailingQueryFindPublisherPreparer(query, domainType));
+		}
+
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.ReactiveFindOperation.FindWithQuery#near(org.springframework.data.mongodb.core.query.NearQuery)
@@ -196,6 +205,18 @@ class ReactiveFindOperationSupport implements ReactiveFindOperation {
 			return template.exists(query, domainType, getCollectionName());
 		}
 
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveFindOperation.FindDistinct#distinct(java.lang.String)
+		 */
+		@Override
+		public TerminatingDistinct<Object> distinct(String field) {
+
+			Assert.notNull(field, "Field must not be null!");
+
+			return new DistinctOperationSupport<>(this, field);
+		}
+
 		private Flux<T> doFind(@Nullable FindPublisherPreparer preparer) {
 
 			Document queryObject = query.getQueryObject();
@@ -205,6 +226,13 @@ class ReactiveFindOperationSupport implements ReactiveFindOperation {
 					preparer != null ? preparer : getCursorPreparer(query));
 		}
 
+		@SuppressWarnings("unchecked")
+		private Flux<T> doFindDistinct(String field) {
+
+			return template.findDistinct(query, field, getCollectionName(), domainType,
+					returnType == domainType ? (Class<T>) Object.class : returnType);
+		}
+
 		private FindPublisherPreparer getCursorPreparer(Query query) {
 			return template.new QueryFindPublisherPreparer(query, domainType);
 		}
@@ -216,5 +244,55 @@ class ReactiveFindOperationSupport implements ReactiveFindOperation {
 		private String asString() {
 			return SerializationUtils.serializeToJsonSafely(query);
 		}
+
+		/**
+		 * @author Christoph Strobl
+		 * @since 2.1
+		 */
+		static class DistinctOperationSupport<T> implements TerminatingDistinct<T> {
+
+			private final String field;
+			private final ReactiveFindSupport delegate;
+
+			public DistinctOperationSupport(ReactiveFindSupport delegate, String field) {
+
+				this.delegate = delegate;
+				this.field = field;
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.ReactiveFindOperation.DistinctWithProjection#as(java.lang.Class)
+			 */
+			@Override
+			public <R> TerminatingDistinct<R> as(Class<R> resultType) {
+
+				Assert.notNull(resultType, "ResultType must not be null!");
+
+				return new DistinctOperationSupport<>((ReactiveFindSupport) delegate.as(resultType), field);
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core.ReactiveFindOperation.DistinctWithQuery#matching(org.springframework.data.mongodb.core.query.Query)
+			 */
+			@Override
+			@SuppressWarnings("unchecked")
+			public TerminatingDistinct<T> matching(Query query) {
+
+				Assert.notNull(query, "Query must not be null!");
+
+				return new DistinctOperationSupport<>((ReactiveFindSupport<T>) delegate.matching(query), field);
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * @see org.springframework.data.mongodb.core..ReactiveFindOperation.TerminatingDistinct#all()
+			 */
+			@Override
+			public Flux<T> all() {
+				return delegate.doFindDistinct(field);
+			}
+		}
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveFluentMongoOperations.java

@@ -19,7 +19,8 @@ package org.springframework.data.mongodb.core;
  * Stripped down interface providing access to a fluent API that specifies a basic set of reactive MongoDB operations.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.0
  */
 public interface ReactiveFluentMongoOperations extends ReactiveFindOperation, ReactiveInsertOperation,
-		ReactiveUpdateOperation, ReactiveRemoveOperation, ReactiveAggregationOperation {}
+		ReactiveUpdateOperation, ReactiveRemoveOperation, ReactiveAggregationOperation, ReactiveMapReduceOperation {}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMapReduceOperation.java

@@ -0,0 +1,199 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import reactor.core.publisher.Flux;
+
+import org.springframework.data.mongodb.core.ExecutableFindOperation.ExecutableFind;
+import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
+import org.springframework.data.mongodb.core.query.Query;
+
+/**
+ * {@link ReactiveMapReduceOperation} allows creation and execution of MongoDB mapReduce operations in a fluent API
+ * style. The starting {@literal domainType} is used for mapping an optional {@link Query} provided via {@code matching}
+ * into the MongoDB specific representation. By default, the originating {@literal domainType} is also used for mapping
+ * back the results from the {@link org.bson.Document}. However, it is possible to define an different
+ * {@literal returnType} via {@code as} to mapping the result.<br />
+ * The collection to operate on is by default derived from the initial {@literal domainType} and can be defined there
+ * via {@link org.springframework.data.mongodb.core.mapping.Document}. Using {@code inCollection} allows to override the
+ * collection name for the execution.
+ * 
+ * <pre>
+ *     <code>
+ *         mapReduce(Human.class)
+ *             .map("function() { emit(this.id, this.firstname) }")
+ *             .reduce("function(id, name) { return sum(id, name); }")
+ *             .inCollection("star-wars")
+ *             .as(Jedi.class)
+ *             .matching(query(where("lastname").is("skywalker")))
+ *             .all();
+ *     </code>
+ * </pre>
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public interface ReactiveMapReduceOperation {
+
+	/**
+	 * Start creating a mapReduce operation for the given {@literal domainType}.
+	 *
+	 * @param domainType must not be {@literal null}.
+	 * @return new instance of {@link ExecutableFind}.
+	 * @throws IllegalArgumentException if domainType is {@literal null}.
+	 */
+	<T> MapReduceWithMapFunction<T> mapReduce(Class<T> domainType);
+
+	/**
+	 * Trigger mapReduce execution by calling one of the terminating methods.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface TerminatingMapReduce<T> {
+
+		/**
+		 * Get the {@link Flux} emitting mapReduce results.
+		 *
+		 * @return a {@link Flux} emitting the already mapped operation results.
+		 */
+		Flux<T> all();
+	}
+
+	/**
+	 * Provide the Javascript {@code function()} used to map matching documents.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithMapFunction<T> {
+
+		/**
+		 * Set the Javascript map {@code function()}.
+		 *
+		 * @param mapFunction must not be {@literal null} nor empty.
+		 * @return new instance of {@link MapReduceWithReduceFunction}.
+		 * @throws IllegalArgumentException if {@literal mapFunction} is {@literal null} or empty.
+		 */
+		MapReduceWithReduceFunction<T> map(String mapFunction);
+
+	}
+
+	/**
+	 * Provide the Javascript {@code function()} used to reduce matching documents.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithReduceFunction<T> {
+
+		/**
+		 * Set the Javascript map {@code function()}.
+		 *
+		 * @param reduceFunction must not be {@literal null} nor empty.
+		 * @return new instance of {@link ReactiveMapReduce}.
+		 * @throws IllegalArgumentException if {@literal reduceFunction} is {@literal null} or empty.
+		 */
+		ReactiveMapReduce<T> reduce(String reduceFunction);
+
+	}
+
+	/**
+	 * Collection override (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithCollection<T> extends MapReduceWithQuery<T> {
+
+		/**
+		 * Explicitly set the name of the collection to perform the mapReduce operation on. <br />
+		 * Skip this step to use the default collection derived from the domain type.
+		 *
+		 * @param collection must not be {@literal null} nor {@literal empty}.
+		 * @return new instance of {@link MapReduceWithProjection}.
+		 * @throws IllegalArgumentException if collection is {@literal null}.
+		 */
+		MapReduceWithProjection<T> inCollection(String collection);
+	}
+
+	/**
+	 * Input document filter query (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithQuery<T> extends TerminatingMapReduce<T> {
+
+		/**
+		 * Set the filter query to be used.
+		 *
+		 * @param query must not be {@literal null}.
+		 * @return new instance of {@link TerminatingMapReduce}.
+		 * @throws IllegalArgumentException if query is {@literal null}.
+		 */
+		TerminatingMapReduce<T> matching(Query query);
+	}
+
+	/**
+	 * Result type override (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithProjection<T> extends MapReduceWithQuery<T> {
+
+		/**
+		 * Define the target type fields should be mapped to. <br />
+		 * Skip this step if you are anyway only interested in the original domain type.
+		 *
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link TerminatingMapReduce}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		<R> MapReduceWithQuery<R> as(Class<R> resultType);
+	}
+
+	/**
+	 * Additional mapReduce options (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface MapReduceWithOptions<T> {
+
+		/**
+		 * Set additional options to apply to the mapReduce operation.
+		 *
+		 * @param options must not be {@literal null}.
+		 * @return new instance of {@link ReactiveMapReduce}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
+		 */
+		ReactiveMapReduce<T> with(MapReduceOptions options);
+	}
+
+	/**
+	 * {@link ReactiveMapReduce} provides methods for constructing reactive mapReduce operations in a fluent way.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface ReactiveMapReduce<T> extends MapReduceWithMapFunction<T>, MapReduceWithReduceFunction<T>,
+			MapReduceWithCollection<T>, MapReduceWithProjection<T>, MapReduceWithOptions<T> {
+
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMapReduceOperationSupport.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import reactor.core.publisher.Flux;
+
+import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Implementation of {@link ReactiveMapReduceOperation}.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+@RequiredArgsConstructor
+class ReactiveMapReduceOperationSupport implements ReactiveMapReduceOperation {
+
+	private static final Query ALL_QUERY = new Query();
+
+	private final @NonNull ReactiveMongoTemplate template;
+
+	/*
+	 * (non-Javascript)
+	 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation#mapReduce(java.lang.Class)
+	 */
+	@Override
+	public <T> ReactiveMapReduceSupport<T> mapReduce(Class<T> domainType) {
+
+		Assert.notNull(domainType, "DomainType must not be null!");
+
+		return new ReactiveMapReduceSupport<>(template, domainType, domainType, null, ALL_QUERY, null, null, null);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	static class ReactiveMapReduceSupport<T>
+			implements ReactiveMapReduce<T>, MapReduceWithOptions<T>, MapReduceWithCollection<T>, MapReduceWithProjection<T>,
+			MapReduceWithQuery<T>, MapReduceWithReduceFunction<T>, MapReduceWithMapFunction<T> {
+
+		private final ReactiveMongoTemplate template;
+		private final Class<?> domainType;
+		private final Class<T> returnType;
+		private final @Nullable String collection;
+		private final Query query;
+		private final @Nullable String mapFunction;
+		private final @Nullable String reduceFunction;
+		private final @Nullable MapReduceOptions options;
+
+		ReactiveMapReduceSupport(ReactiveMongoTemplate template, Class<?> domainType, Class<T> returnType,
+				@Nullable String collection, Query query, @Nullable String mapFunction, @Nullable String reduceFunction,
+				@Nullable MapReduceOptions options) {
+
+			this.template = template;
+			this.domainType = domainType;
+			this.returnType = returnType;
+			this.collection = collection;
+			this.query = query;
+			this.mapFunction = mapFunction;
+			this.reduceFunction = reduceFunction;
+			this.options = options;
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ExecutableMapReduceOperation.TerminatingMapReduce#all()
+		 */
+		@Override
+		public Flux<T> all() {
+
+			return template.mapReduce(query, domainType, getCollectionName(), returnType, mapFunction, reduceFunction,
+					options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithCollection#inCollection(java.lang.String)
+		 */
+		@Override
+		public MapReduceWithProjection<T> inCollection(String collection) {
+
+			Assert.hasText(collection, "Collection name must not be null nor empty!");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithQuery#query(org.springframework.data.mongodb.core.query.Query)
+		 */
+		@Override
+		public TerminatingMapReduce<T> matching(Query query) {
+
+			Assert.notNull(query, "Query must not be null!");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithProjection#as(java.lang.Class)
+		 */
+		@Override
+		public <R> MapReduceWithQuery<R> as(Class<R> resultType) {
+
+			Assert.notNull(resultType, "ResultType must not be null!");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, resultType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithOptions#with(org.springframework.data.mongodb.core.mapreduce.MapReduceOptions)
+		 */
+		@Override
+		public ReactiveMapReduce<T> with(MapReduceOptions options) {
+
+			Assert.notNull(options, "Options must not be null! Please consider empty MapReduceOptions#options() instead.");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithMapFunction#map(java.lang.String)
+		 */
+		@Override
+		public MapReduceWithReduceFunction<T> map(String mapFunction) {
+
+			Assert.hasText(mapFunction, "MapFunction name must not be null nor empty!");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		/*
+		 * (non-Javascript)
+		 * @see in org.springframework.data.mongodb.core.ReactiveMapReduceOperation.MapReduceWithReduceFunction#reduce(java.lang.String)
+		 */
+		@Override
+		public ReactiveMapReduce<T> reduce(String reduceFunction) {
+
+			Assert.hasText(reduceFunction, "ReduceFunction name must not be null nor empty!");
+
+			return new ReactiveMapReduceSupport<>(template, domainType, returnType, collection, query, mapFunction,
+					reduceFunction, options);
+		}
+
+		private String getCollectionName() {
+			return StringUtils.hasText(collection) ? collection : template.determineCollectionName(domainType);
+		}
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoContext.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import org.reactivestreams.Publisher;
+import org.springframework.util.Assert;
+import reactor.core.publisher.Mono;
+import reactor.util.context.Context;
+
+import com.mongodb.reactivestreams.client.ClientSession;
+
+/**
+ * {@link ReactiveMongoContext} utilizes and enriches the Reactor {@link Context} with information potentially required
+ * for e.g. {@link ClientSession} handling and transactions.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ * @see Mono#subscriberContext()
+ * @see Context
+ */
+public class ReactiveMongoContext {
+
+	private static final Class<?> SESSION_KEY = ClientSession.class;
+
+	/**
+	 * Gets the {@code Mono<ClientSession>} from Reactor {@link reactor.util.context.Context}. The resulting {@link Mono}
+	 * emits the {@link ClientSession} if a session is associated with the current {@link reactor.util.context.Context
+	 * subscriber context}. If the context does not contain a session, the resulting {@link Mono} terminates empty (i.e.
+	 * without emitting a value).
+	 *
+	 * @return the {@link Mono} emitting the client session if present; otherwise the {@link Mono} terminates empty.
+	 */
+	public static Mono<ClientSession> getSession() {
+
+		return Mono.subscriberContext().filter(ctx -> ctx.hasKey(SESSION_KEY))
+				.flatMap(ctx -> ctx.<Mono<ClientSession>> get(SESSION_KEY));
+	}
+
+	/**
+	 * Sets the {@link ClientSession} into the Reactor {@link reactor.util.context.Context}.
+	 *
+	 * @param context must not be {@literal null}.
+	 * @param session must not be {@literal null}.
+	 * @return a new {@link Context}.
+	 * @see Context#put(Object, Object)
+	 */
+	public static Context setSession(Context context, Publisher<ClientSession> session) {
+
+		Assert.notNull(context, "Context must not be null!");
+		Assert.notNull(session, "Session publisher must not be null!");
+
+		return context.put(SESSION_KEY, Mono.from(session));
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoOperations.java

@@ -19,27 +19,35 @@ import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import java.util.Collection;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
 
 import org.bson.Document;
 import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscription;
 import org.springframework.data.geo.GeoResult;
+import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
 import org.springframework.data.mongodb.core.aggregation.Aggregation;
 import org.springframework.data.mongodb.core.aggregation.AggregationOptions;
 import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.convert.MongoConverter;
 import org.springframework.data.mongodb.core.index.ReactiveIndexOperations;
+import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
 import org.springframework.data.mongodb.core.query.BasicQuery;
 import org.springframework.data.mongodb.core.query.Criteria;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
+import com.mongodb.ClientSessionOptions;
 import com.mongodb.ReadPreference;
 import com.mongodb.client.result.DeleteResult;
 import com.mongodb.client.result.UpdateResult;
+import com.mongodb.reactivestreams.client.ClientSession;
 import com.mongodb.reactivestreams.client.MongoCollection;
 
 /**
@@ -140,6 +148,92 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 */
 	<T> Flux<T> execute(String collectionName, ReactiveCollectionCallback<T> action);
 
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link SessionScoped} binding the {@link ClientSession}
+	 * provided by the given {@link Supplier} to each and every command issued against MongoDB.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle. Use
+	 * {@link ReactiveSessionScoped#execute(ReactiveSessionCallback, Consumer)} to provide a hook for processing the
+	 * {@link ClientSession} when done.
+	 *
+	 * @param sessionProvider must not be {@literal null}.
+	 * @return new instance of {@link ReactiveSessionScoped}. Never {@literal null}.
+	 * @since 2.1
+	 */
+	default ReactiveSessionScoped withSession(Supplier<ClientSession> sessionProvider) {
+
+		Assert.notNull(sessionProvider, "SessionProvider must not be null!");
+
+		return withSession(Mono.fromSupplier(sessionProvider));
+	}
+
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link SessionScoped} binding a new {@link ClientSession}
+	 * with given {@literal sessionOptions} to each and every command issued against MongoDB.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle. Use
+	 * {@link ReactiveSessionScoped#execute(ReactiveSessionCallback, Consumer)} to provide a hook for processing the
+	 * {@link ClientSession} when done.
+	 *
+	 * @param sessionOptions must not be {@literal null}.
+	 * @return new instance of {@link ReactiveSessionScoped}. Never {@literal null}.
+	 * @since 2.1
+	 */
+	ReactiveSessionScoped withSession(ClientSessionOptions sessionOptions);
+
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link ReactiveSessionScoped} binding the
+	 * {@link ClientSession} provided by the given {@link Publisher} to each and every command issued against MongoDB.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle. Use
+	 * {@link ReactiveSessionScoped#execute(ReactiveSessionCallback, Consumer)} to provide a hook for processing the
+	 * {@link ClientSession} when done.
+	 *
+	 * @param sessionProvider must not be {@literal null}.
+	 * @return new instance of {@link ReactiveSessionScoped}. Never {@literal null}.
+	 * @since 2.1
+	 */
+	ReactiveSessionScoped withSession(Publisher<ClientSession> sessionProvider);
+
+	/**
+	 * Obtain a {@link ClientSession} bound instance of {@link ReactiveMongoOperations}.
+	 * <p />
+	 * <strong>Note:</strong> It is up to the caller to manage the {@link ClientSession} lifecycle.
+	 *
+	 * @param session must not be {@literal null}.
+	 * @return {@link ClientSession} bound instance of {@link ReactiveMongoOperations}.
+	 * @since 2.1
+	 */
+	ReactiveMongoOperations withSession(ClientSession session);
+
+	/**
+	 * Initiate a new {@link ClientSession} and obtain a {@link ClientSession session} bound instance of
+	 * {@link ReactiveSessionScoped}. Starts the transaction and adds the {@link ClientSession} to each and every command
+	 * issued against MongoDB.
+	 * <p/>
+	 * Each {@link ReactiveSessionScoped#execute(ReactiveSessionCallback) execution} initiates a new managed transaction
+	 * that is {@link ClientSession#commitTransaction() committed} on success. Transactions are
+	 * {@link ClientSession#abortTransaction() rolled back} upon errors.
+	 *
+	 * @return new instance of {@link ReactiveSessionScoped}. Never {@literal null}.
+	 */
+	ReactiveSessionScoped inTransaction();
+
+	/**
+	 * Obtain a {@link ClientSession session} bound instance of {@link ReactiveSessionScoped}, start the transaction and
+	 * bind the {@link ClientSession} provided by the given {@link Publisher} to each and every command issued against
+	 * MongoDB.
+	 * <p/>
+	 * Each {@link ReactiveSessionScoped#execute(ReactiveSessionCallback) execution} initiates a new managed transaction
+	 * that is {@link ClientSession#commitTransaction() committed} on success. Transactions are
+	 * {@link ClientSession#abortTransaction() rolled back} upon errors.
+	 *
+	 * @param sessionProvider must not be {@literal null}.
+	 * @return new instance of {@link ReactiveSessionScoped}. Never {@literal null}.
+	 * @since 2.1
+	 */
+	ReactiveSessionScoped inTransaction(Publisher<ClientSession> sessionProvider);
+
 	/**
 	 * Create an uncapped collection with a name based on the provided entity class.
 	 *
@@ -377,6 +471,65 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 */
 	<T> Mono<T> findById(Object id, Class<T> entityClass, String collectionName);
 
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link Flux}.
+	 *
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param entityClass the domain type used for determining the actual {@link MongoCollection}. Must not be
+	 *          {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default <T> Flux<T> findDistinct(String field, Class<?> entityClass, Class<T> resultClass) {
+		return findDistinct(new Query(), field, entityClass, resultClass);
+	}
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link Flux}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param entityClass the domain type used for determining the actual {@link MongoCollection} and mapping the
+	 *          {@link Query} to the domain type fields. Must not be {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> Flux<T> findDistinct(Query query, String field, Class<?> entityClass, Class<T> resultClass);
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link Flux}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param collectionName the explicit name of the actual {@link MongoCollection}. Must not be {@literal null}.
+	 * @param entityClass the domain type used for mapping the {@link Query} to the domain type fields.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> Flux<T> findDistinct(Query query, String field, String collectionName, Class<?> entityClass,
+			Class<T> resultClass);
+
+	/**
+	 * Finds the distinct values for a specified {@literal field} across a single {@link MongoCollection} or view and
+	 * returns the results in a {@link Flux}.
+	 *
+	 * @param query filter {@link Query} to restrict search. Must not be {@literal null}.
+	 * @param field the name of the field to inspect for distinct values. Must not be {@literal null}.
+	 * @param collection the explicit name of the actual {@link MongoCollection}. Must not be {@literal null}.
+	 * @param resultClass the result type. Must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default <T> Flux<T> findDistinct(Query query, String field, String collection, Class<T> resultClass) {
+		return findDistinct(query, field, collection, Object.class, resultClass);
+	}
+
 	/**
 	 * Execute an aggregation operation.
 	 * <p>
@@ -536,6 +689,160 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	<T> Mono<T> findAndModify(Query query, Update update, FindAndModifyOptions options, Class<T> entityClass,
 			String collectionName);
 
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement}
+	 * document. <br />
+	 * Options are defaulted to {@link FindAndReplaceOptions#empty()}. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found.
+	 * @since 2.1
+	 */
+	default <T> Mono<T> findAndReplace(Query query, T replacement) {
+		return findAndReplace(query, replacement, FindAndReplaceOptions.empty());
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement}
+	 * document. <br />
+	 * Options are defaulted to {@link FindAndReplaceOptions#empty()}. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found.
+	 * @since 2.1
+	 */
+	default <T> Mono<T> findAndReplace(Query query, T replacement, String collectionName) {
+		return findAndReplace(query, replacement, FindAndReplaceOptions.empty(), collectionName);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	default <T> Mono<T> findAndReplace(Query query, T replacement, FindAndReplaceOptions options) {
+		return findAndReplace(query, replacement, options, getCollectionName(ClassUtils.getUserClass(replacement)));
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	default <T> Mono<T> findAndReplace(Query query, T replacement, FindAndReplaceOptions options, String collectionName) {
+
+		Assert.notNull(replacement, "Replacement must not be null!");
+		return findAndReplace(query, replacement, options, (Class<T>) ClassUtils.getUserClass(replacement), collectionName);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the parametrized type. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	default <T> Mono<T> findAndReplace(Query query, T replacement, FindAndReplaceOptions options, Class<T> entityType,
+			String collectionName) {
+
+		return findAndReplace(query, replacement, options, entityType, collectionName, entityType);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the type used for mapping the {@link Query} to domain type fields and deriving the collection
+	 *          from. Must not be {@literal null}.
+	 * @param resultType the parametrized type projection return type. Must not be {@literal null}, use the domain type of
+	 *          {@code Object.class} instead.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	default <S, T> Mono<T> findAndReplace(Query query, S replacement, FindAndReplaceOptions options, Class<S> entityType,
+			Class<T> resultType) {
+
+		return findAndReplace(query, replacement, options, entityType,
+				getCollectionName(ClassUtils.getUserClass(entityType)), resultType);
+	}
+
+	/**
+	 * Triggers
+	 * <a href="https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndReplace/">findOneAndReplace<a/>
+	 * to replace a single document matching {@link Criteria} of given {@link Query} with the {@code replacement} document
+	 * taking {@link FindAndReplaceOptions} into account. <br />
+	 * <strong>NOTE:</strong> The replacement entity must not hold an {@literal id}.
+	 *
+	 * @param query the {@link Query} class that specifies the {@link Criteria} used to find a record and also an optional
+	 *          fields specification. Must not be {@literal null}.
+	 * @param replacement the replacement document. Must not be {@literal null}.
+	 * @param options the {@link FindAndModifyOptions} holding additional information. Must not be {@literal null}.
+	 * @param entityType the type used for mapping the {@link Query} to domain type fields and deriving the collection
+	 *          from. Must not be {@literal null}.
+	 * @param collectionName the collection to query. Must not be {@literal null}.
+	 * @param resultType resultType the parametrized type projection return type. Must not be {@literal null}, use the
+	 *          domain type of {@code Object.class} instead.
+	 * @return the converted object that was updated or {@link Mono#empty()}, if not found. Depending on the value of
+	 *         {@link FindAndReplaceOptions#isReturnNew()} this will either be the object as it was before the update or
+	 *         as it is after the update.
+	 * @since 2.1
+	 */
+	<S, T> Mono<T> findAndReplace(Query query, S replacement, FindAndReplaceOptions options, Class<S> entityType,
+			String collectionName, Class<T> resultType);
+
 	/**
 	 * Map the results of an ad-hoc query on the collection for the entity type to a single instance of an object of the
 	 * specified type. The first document that matches the query is returned and also removed from the collection in the
@@ -613,14 +920,14 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" >
-	 * Spring's Type Conversion"</a> for more details.
+	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" > Spring's Type
+	 * Conversion"</a> for more details.
 	 * <p/>
 	 * <p/>
 	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
-	 * @return the saved object.
+	 * @return the inserted object.
 	 */
 	<T> Mono<T> insert(T objectToSave);
 
@@ -634,7 +941,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
-	 * @return the saved object.
+	 * @return the inserted object.
 	 */
 	<T> Mono<T> insert(T objectToSave, String collectionName);
 
@@ -643,7 +950,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 *
 	 * @param batchToSave the batch of objects to save. Must not be {@literal null}.
 	 * @param entityClass class that determines the collection to use. Must not be {@literal null}.
-	 * @return the saved objects.
+	 * @return the inserted objects .
 	 */
 	<T> Flux<T> insert(Collection<? extends T> batchToSave, Class<?> entityClass);
 
@@ -652,7 +959,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 *
 	 * @param batchToSave the list of objects to save. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
-	 * @return the saved objects.
+	 * @return the inserted objects.
 	 */
 	<T> Flux<T> insert(Collection<? extends T> batchToSave, String collectionName);
 
@@ -673,14 +980,14 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" >
-	 * Spring's Type Conversion"</a> for more details.
+	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" > Spring's Type
+	 * Conversion"</a> for more details.
 	 * <p/>
 	 * <p/>
 	 * Insert is used to initially store the object into the database. To update an existing object use the save method.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
-	 * @return the saved object.
+	 * @return the inserted objects.
 	 */
 	<T> Mono<T> insert(Mono<? extends T> objectToSave);
 
@@ -689,7 +996,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 *
 	 * @param batchToSave the publisher which provides objects to save. Must not be {@literal null}.
 	 * @param entityClass class that determines the collection to use. Must not be {@literal null}.
-	 * @return the saved objects.
+	 * @return the inserted objects.
 	 */
 	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> batchToSave, Class<?> entityClass);
 
@@ -698,7 +1005,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 *
 	 * @param batchToSave the publisher which provides objects to save. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
-	 * @return the saved objects.
+	 * @return the inserted objects.
 	 */
 	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> batchToSave, String collectionName);
 
@@ -707,7 +1014,7 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * class.
 	 *
 	 * @param objectsToSave the publisher which provides objects to save. Must not be {@literal null}.
-	 * @return the saved objects.
+	 * @return the inserted objects.
 	 */
 	<T> Flux<T> insertAll(Mono<? extends Collection<? extends T>> objectsToSave);
 
@@ -721,8 +1028,8 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" >
-	 * Spring's Type Conversion"</a> for more details.
+	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" > Spring's Type
+	 * Conversion"</a> for more details.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @return the saved object.
@@ -739,8 +1046,8 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See <a
-	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation">Spring's
-	 * Type Conversion"</a> for more details.
+	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation">Spring's Type
+	 * Conversion"</a> for more details.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
@@ -758,8 +1065,8 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See
-	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" >
-	 * Spring's Type Conversion"</a> for more details.
+	 * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation" > Spring's Type
+	 * Conversion"</a> for more details.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @return the saved object.
@@ -776,8 +1083,8 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 * If you object has an "Id' property, it will be set with the generated Id from MongoDB. If your Id property is a
 	 * String then MongoDB ObjectId will be used to populate that string. Otherwise, the conversion from ObjectId to your
 	 * property type will be handled by Spring's BeanWrapper class that leverages Type Conversion API. See <a
-	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation">Spring's
-	 * Type Conversion"</a> for more details.
+	 * http://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation">Spring's Type
+	 * Conversion"</a> for more details.
 	 *
 	 * @param objectToSave the object to store in the collection. Must not be {@literal null}.
 	 * @param collectionName name of the collection to store the object in. Must not be {@literal null}.
@@ -1049,6 +1356,115 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 */
 	<T> Flux<T> tail(Query query, Class<T> entityClass, String collectionName);
 
+	/**
+	 * Subscribe to a MongoDB <a href="https://docs.mongodb.com/manual/changeStreams/">Change Stream</a> for all events in
+	 * the configured default database via the reactive infrastructure. Use the optional provided {@link Aggregation} to
+	 * filter events. The stream will not be completed unless the {@link org.reactivestreams.Subscription} is
+	 * {@link Subscription#cancel() canceled}.
+	 * <p />
+	 * The {@link ChangeStreamEvent#getBody()} is mapped to the {@literal resultType} while the
+	 * {@link ChangeStreamEvent#getRaw()} contains the unmodified payload.
+	 * <p />
+	 * Use {@link ChangeStreamOptions} to set arguments like {@link ChangeStreamOptions#getResumeToken() the resumseToken}
+	 * for resuming change streams.
+	 *
+	 * @param options must not be {@literal null}. Use {@link ChangeStreamOptions#empty()}.
+	 * @param targetType the result type to use.
+	 * @param <T>
+	 * @return the {@link Flux} emitting {@link ChangeStreamEvent events} as they arrive.
+	 * @since 2.1
+	 * @see ReactiveMongoDatabaseFactory#getMongoDatabase()
+	 * @see ChangeStreamOptions#getFilter()
+	 */
+	default <T> Flux<ChangeStreamEvent<T>> changeStream(ChangeStreamOptions options, Class<T> targetType) {
+		return changeStream(null, options, targetType);
+	}
+
+	/**
+	 * Subscribe to a MongoDB <a href="https://docs.mongodb.com/manual/changeStreams/">Change Stream</a> for all events in
+	 * the given collection via the reactive infrastructure. Use the optional provided {@link Aggregation} to filter
+	 * events. The stream will not be completed unless the {@link org.reactivestreams.Subscription} is
+	 * {@link Subscription#cancel() canceled}.
+	 * <p />
+	 * The {@link ChangeStreamEvent#getBody()} is mapped to the {@literal resultType} while the
+	 * {@link ChangeStreamEvent#getRaw()} contains the unmodified payload.
+	 * <p />
+	 * Use {@link ChangeStreamOptions} to set arguments like {@link ChangeStreamOptions#getResumeToken() the resumseToken}
+	 * for resuming change streams.
+	 *
+	 * @param collectionName the collection to watch. Can be {@literal null} to watch all collections.
+	 * @param options must not be {@literal null}. Use {@link ChangeStreamOptions#empty()}.
+	 * @param targetType the result type to use.
+	 * @param <T>
+	 * @return the {@link Flux} emitting {@link ChangeStreamEvent events} as they arrive.
+	 * @since 2.1
+	 * @see ChangeStreamOptions#getFilter()
+	 */
+	default <T> Flux<ChangeStreamEvent<T>> changeStream(@Nullable String collectionName, ChangeStreamOptions options,
+			Class<T> targetType) {
+
+		return changeStream(null, collectionName, options, targetType);
+	}
+
+	/**
+	 * Subscribe to a MongoDB <a href="https://docs.mongodb.com/manual/changeStreams/">Change Stream</a> via the reactive
+	 * infrastructure. Use the optional provided {@link Aggregation} to filter events. The stream will not be completed
+	 * unless the {@link org.reactivestreams.Subscription} is {@link Subscription#cancel() canceled}.
+	 * <p />
+	 * The {@link ChangeStreamEvent#getBody()} is mapped to the {@literal resultType} while the
+	 * {@link ChangeStreamEvent#getRaw()} contains the unmodified payload.
+	 * <p />
+	 * Use {@link ChangeStreamOptions} to set arguments like {@link ChangeStreamOptions#getResumeToken() the resumseToken}
+	 * for resuming change streams.
+	 *
+	 * @param database the database to watch. Can be {@literal null}, uses configured default if so.
+	 * @param collectionName the collection to watch. Can be {@literal null}, watches all collections if so.
+	 * @param options must not be {@literal null}. Use {@link ChangeStreamOptions#empty()}.
+	 * @param targetType the result type to use.
+	 * @param <T>
+	 * @return the {@link Flux} emitting {@link ChangeStreamEvent events} as they arrive.
+	 * @since 2.1
+	 * @see ChangeStreamOptions#getFilter()
+	 */
+	<T> Flux<ChangeStreamEvent<T>> changeStream(@Nullable String database, @Nullable String collectionName,
+			ChangeStreamOptions options, Class<T> targetType);
+
+	/**
+	 * Execute a map-reduce operation. Use {@link MapReduceOptions} to optionally specify an output collection and other
+	 * args.
+	 *
+	 * @param filterQuery the selection criteria for the documents going input to the map function. Must not be
+	 *          {@literal null}.
+	 * @param domainType source type used to determine the input collection name and map the filter {@link Query} against.
+	 *          Must not be {@literal null}.
+	 * @param resultType the mapping target of the operations result documents. Must not be {@literal null}.
+	 * @param mapFunction the JavaScript map function. Must not be {@literal null}.
+	 * @param reduceFunction the JavaScript reduce function. Must not be {@literal null}.
+	 * @param options additional options like output collection. Must not be {@literal null}.
+	 * @return a {@link Flux} emitting the result document sequence. Never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> Flux<T> mapReduce(Query filterQuery, Class<?> domainType, Class<T> resultType, String mapFunction,
+			String reduceFunction, MapReduceOptions options);
+
+	/**
+	 * Execute a map-reduce operation. Use {@link MapReduceOptions} to optionally specify an output collection and other
+	 * args.
+	 *
+	 * @param filterQuery the selection criteria for the documents going input to the map function. Must not be
+	 *          {@literal null}.
+	 * @param domainType source type used to map the filter {@link Query} against. Must not be {@literal null}.
+	 * @param inputCollectionName the input collection.
+	 * @param resultType the mapping target of the operations result documents. Must not be {@literal null}.
+	 * @param mapFunction the JavaScript map function. Must not be {@literal null}.
+	 * @param reduceFunction the JavaScript reduce function. Must not be {@literal null}.
+	 * @param options additional options like output collection. Must not be {@literal null}.
+	 * @return a {@link Flux} emitting the result document sequence. Never {@literal null}.
+	 * @since 2.1
+	 */
+	<T> Flux<T> mapReduce(Query filterQuery, Class<?> domainType, String inputCollectionName, Class<T> resultType,
+			String mapFunction, String reduceFunction, MapReduceOptions options);
+
 	/**
 	 * Returns the underlying {@link MongoConverter}.
 	 *
@@ -1056,4 +1472,13 @@ public interface ReactiveMongoOperations extends ReactiveFluentMongoOperations {
 	 */
 	MongoConverter getConverter();
 
+	/**
+	 * The collection name used for the specified class by this template.
+	 *
+	 * @param entityClass must not be {@literal null}.
+	 * @return
+	 * @since 2.1
+	 */
+	String getCollectionName(Class<?> entityClass);
+
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveSessionCallback.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import org.reactivestreams.Publisher;
+import org.springframework.data.mongodb.core.query.Query;
+
+/**
+ * Callback interface for executing operations within a {@link com.mongodb.reactivestreams.client.ClientSession} using
+ * reactive infrastructure.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ * @see com.mongodb.reactivestreams.client.ClientSession
+ */
+@FunctionalInterface
+public interface ReactiveSessionCallback<T> {
+
+	/**
+	 * Execute operations against a MongoDB instance via session bound {@link ReactiveMongoOperations}. The session is
+	 * inferred directly into the operation so that no further interaction is necessary.
+	 * <p />
+	 * Please note that only Spring Data-specific abstractions like {@link ReactiveMongoOperations#find(Query, Class)} and
+	 * others are enhanced with the {@link com.mongodb.session.ClientSession}. When obtaining plain MongoDB gateway
+	 * objects like {@link com.mongodb.reactivestreams.client.MongoCollection} or
+	 * {@link com.mongodb.reactivestreams.client.MongoDatabase} via eg.
+	 * {@link ReactiveMongoOperations#getCollection(String)} we leave responsibility for
+	 * {@link com.mongodb.session.ClientSession} again up to the caller.
+	 *
+	 * @param operations will never be {@literal null}.
+	 * @return never {@literal null}.
+	 */
+	Publisher<T> doInSession(ReactiveMongoOperations operations);
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveSessionScoped.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import reactor.core.publisher.Flux;
+
+import java.util.function.Consumer;
+
+import com.mongodb.reactivestreams.client.ClientSession;
+
+/**
+ * Gateway interface to execute {@link ClientSession} bound operations against MongoDB via a
+ * {@link ReactiveSessionCallback}.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+public interface ReactiveSessionScoped {
+
+	/**
+	 * Executes the given {@link ReactiveSessionCallback} within the {@link com.mongodb.session.ClientSession}.
+	 * <p/>
+	 * It is up to the caller to make sure the {@link com.mongodb.session.ClientSession} is {@link ClientSession#close()
+	 * closed} when done.
+	 *
+	 * @param action callback object that specifies the MongoDB action the callback action. Must not be {@literal null}.
+	 * @param <T> return type.
+	 * @return a result object returned by the action, can be {@link Flux#empty()}.
+	 */
+	default <T> Flux<T> execute(ReactiveSessionCallback<T> action) {
+		return execute(action, (session) -> {});
+	}
+
+	/**
+	 * Executes the given {@link ReactiveSessionCallback} within the {@link com.mongodb.session.ClientSession}.
+	 * <p/>
+	 * It is up to the caller to make sure the {@link com.mongodb.session.ClientSession} is {@link ClientSession#close()
+	 * closed} when done.
+	 *
+	 * @param action callback object that specifies the MongoDB action the callback action. Must not be {@literal null}.
+	 * @param doFinally callback object that accepts {@link ClientSession} after invoking {@link ReactiveSessionCallback}.
+	 *          This {@link Consumer} is guaranteed to be notified in any case (successful and exceptional outcome of
+	 *          {@link ReactiveSessionCallback}).
+	 * @param <T> return type.
+	 * @return a result object returned by the action, can be {@link Flux#empty()}.
+	 */
+	<T> Flux<T> execute(ReactiveSessionCallback<T> action, Consumer<ClientSession> doFinally);
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveUpdateOperation.java

@@ -18,12 +18,13 @@ package org.springframework.data.mongodb.core;
 import reactor.core.publisher.Mono;
 
 import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
 
 import com.mongodb.client.result.UpdateResult;
 
 /**
- * {@link ReactiveUpdateOperation} allows creation and execution of reactive MongoDB update / findAndModify operations
- * in a fluent API style. <br />
+ * {@link ReactiveUpdateOperation} allows creation and execution of reactive MongoDB update / findAndModify /
+ * findAndReplace operations in a fluent API style. <br />
  * The starting {@literal domainType} is used for mapping the {@link Query} provided via {@code matching}, as well as
  * the {@link org.springframework.data.mongodb.core.query.Update} via {@code apply} into the MongoDB specific
  * representations. The collection to operate on is by default derived from the initial {@literal domainType} and can be
@@ -68,6 +69,22 @@ public interface ReactiveUpdateOperation {
 		Mono<T> findAndModify();
 	}
 
+	/**
+	 * Compose findAndReplace execution by calling one of the terminating methods.
+	 *
+	 * @author Mark Paluch
+	 * @since 2.1
+	 */
+	interface TerminatingFindAndReplace<T> {
+
+		/**
+		 * Find, replace and return the first matching document.
+		 *
+		 * @return {@link Mono#empty()} if nothing found. Never {@literal null}.
+		 */
+		Mono<T> findAndReplace();
+	}
+
 	/**
 	 * Compose update execution by calling one of the terminating methods.
 	 */
@@ -108,6 +125,16 @@ public interface ReactiveUpdateOperation {
 		 * @throws IllegalArgumentException if update is {@literal null}.
 		 */
 		TerminatingUpdate<T> apply(org.springframework.data.mongodb.core.query.Update update);
+
+		/**
+		 * Specify {@code replacement} object.
+		 *
+		 * @param replacement must not be {@literal null}.
+		 * @return new instance of {@link FindAndReplaceOptions}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
+		 * @since 2.1
+		 */
+		FindAndReplaceWithProjection<T> replaceWith(T replacement);
 	}
 
 	/**
@@ -157,5 +184,45 @@ public interface ReactiveUpdateOperation {
 		TerminatingFindAndModify<T> withOptions(FindAndModifyOptions options);
 	}
 
+	/**
+	 * Define {@link FindAndReplaceOptions}.
+	 *
+	 * @author Mark Paluch
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface FindAndReplaceWithOptions<T> extends TerminatingFindAndReplace<T> {
+
+		/**
+		 * Explicitly define {@link FindAndReplaceOptions} for the {@link Update}.
+		 *
+		 * @param options must not be {@literal null}.
+		 * @return new instance of {@link FindAndReplaceOptions}.
+		 * @throws IllegalArgumentException if options is {@literal null}.
+		 */
+		FindAndReplaceWithProjection<T> withOptions(FindAndReplaceOptions options);
+	}
+
+	/**
+	 * Result type override (Optional).
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	interface FindAndReplaceWithProjection<T> extends FindAndReplaceWithOptions<T> {
+
+		/**
+		 * Define the target type fields should be mapped to. <br />
+		 * Skip this step if you are anyway only interested in the original domain type.
+		 *
+		 * @param resultType must not be {@literal null}.
+		 * @param <R> result type.
+		 * @return new instance of {@link FindAndReplaceWithProjection}.
+		 * @throws IllegalArgumentException if resultType is {@literal null}.
+		 */
+		<R> FindAndReplaceWithOptions<R> as(Class<R> resultType);
+
+	}
+
 	interface ReactiveUpdate<T> extends UpdateWithCollection<T>, UpdateWithQuery<T>, UpdateWithUpdate<T> {}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveUpdateOperationSupport.java

@@ -22,6 +22,7 @@ import lombok.experimental.FieldDefaults;
 import reactor.core.publisher.Mono;
 
 import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -50,20 +51,24 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 		Assert.notNull(domainType, "DomainType must not be null!");
 
-		return new ReactiveUpdateSupport<>(template, domainType, ALL_QUERY, null, null, null);
+		return new ReactiveUpdateSupport<>(template, domainType, ALL_QUERY, null, null, null, null, null, domainType);
 	}
 
 	@RequiredArgsConstructor
 	@FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
 	static class ReactiveUpdateSupport<T>
-			implements ReactiveUpdate<T>, UpdateWithCollection<T>, UpdateWithQuery<T>, TerminatingUpdate<T> {
+			implements ReactiveUpdate<T>, UpdateWithCollection<T>, UpdateWithQuery<T>, TerminatingUpdate<T>,
+			FindAndReplaceWithOptions<T>, FindAndReplaceWithProjection<T>, TerminatingFindAndReplace<T> {
 
 		@NonNull ReactiveMongoTemplate template;
-		@NonNull Class<T> domainType;
+		@NonNull Class<?> domainType;
 		Query query;
 		org.springframework.data.mongodb.core.query.Update update;
-		String collection;
-		FindAndModifyOptions options;
+		@Nullable String collection;
+		@Nullable FindAndModifyOptions findAndModifyOptions;
+		@Nullable FindAndReplaceOptions findAndReplaceOptions;
+		@Nullable Object replacement;
+		@NonNull Class<T> targetType;
 
 		/*
 		 * (non-Javadoc)
@@ -74,7 +79,8 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 			Assert.notNull(update, "Update must not be null!");
 
-			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
 		}
 
 		/*
@@ -86,7 +92,8 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 			Assert.hasText(collection, "Collection must not be null nor empty!");
 
-			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
 		}
 
 		/*
@@ -116,7 +123,18 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 			String collectionName = getCollectionName();
 
-			return template.findAndModify(query, update, options, domainType, collectionName);
+			return template.findAndModify(query, update, findAndModifyOptions, targetType, collectionName);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveUpdateOperation.TerminatingFindAndReplace#findAndReplace()
+		 */
+		@Override
+		public Mono<T> findAndReplace() {
+			return template.findAndReplace(query, replacement,
+					findAndReplaceOptions != null ? findAndReplaceOptions : new FindAndReplaceOptions(), (Class) domainType,
+					getCollectionName(), targetType);
 		}
 
 		/*
@@ -128,7 +146,8 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 			Assert.notNull(query, "Query must not be null!");
 
-			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
 		}
 
 		/*
@@ -149,7 +168,47 @@ class ReactiveUpdateOperationSupport implements ReactiveUpdateOperation {
 
 			Assert.notNull(options, "Options must not be null!");
 
-			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, options);
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, options,
+					findAndReplaceOptions, replacement, targetType);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveUpdateOperation.UpdateWithUpdate#replaceWith(java.lang.Object)
+		 */
+		@Override
+		public FindAndReplaceWithProjection<T> replaceWith(T replacement) {
+
+			Assert.notNull(replacement, "Replacement must not be null!");
+
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, targetType);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveUpdateOperation.FindAndReplaceWithOptions#withOptions(org.springframework.data.mongodb.core.FindAndReplaceOptions)
+		 */
+		@Override
+		public FindAndReplaceWithProjection<T> withOptions(FindAndReplaceOptions options) {
+
+			Assert.notNull(options, "Options must not be null!");
+
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions, options,
+					replacement, targetType);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.core.ReactiveUpdateOperation.FindAndReplaceWithProjection#as(java.lang.Class)
+		 */
+		@Override
+		public <R> FindAndReplaceWithOptions<R> as(Class<R> resultType) {
+
+			Assert.notNull(resultType, "ResultType must not be null!");
+
+			return new ReactiveUpdateSupport<>(template, domainType, query, update, collection, findAndModifyOptions,
+					findAndReplaceOptions, replacement, resultType);
 		}
 
 		private Mono<UpdateResult> doUpdate(boolean multi, boolean upsert) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ScriptOperations.java

@@ -25,7 +25,7 @@ import com.mongodb.DB;
 
 /**
  * Script operations on {@link com.mongodb.DB} level. Allows interaction with server side JavaScript functions.
- * 
+ *
  * @author Christoph Strobl
  * @author Oliver Gierke
  * @since 1.7
@@ -35,7 +35,7 @@ public interface ScriptOperations {
 	/**
 	 * Store given {@link ExecutableMongoScript} generating a syntheitcal name so that it can be called by it
 	 * subsequently.
-	 * 
+	 *
 	 * @param script must not be {@literal null}.
 	 * @return {@link NamedMongoScript} with name under which the {@code JavaScript} function can be called.
 	 */
@@ -43,7 +43,7 @@ public interface ScriptOperations {
 
 	/**
 	 * Registers the given {@link NamedMongoScript} in the database.
-	 * 
+	 *
 	 * @param script the {@link NamedMongoScript} to be registered.
 	 * @return
 	 */
@@ -51,7 +51,7 @@ public interface ScriptOperations {
 
 	/**
 	 * Executes the {@literal script} by either calling it via its {@literal name} or directly sending it.
-	 * 
+	 *
 	 * @param script must not be {@literal null}.
 	 * @param args arguments to pass on for script execution.
 	 * @return the script evaluation result.
@@ -62,7 +62,7 @@ public interface ScriptOperations {
 
 	/**
 	 * Call the {@literal JavaScript} by its name.
-	 * 
+	 *
 	 * @param scriptName must not be {@literal null} or empty.
 	 * @param args
 	 * @return
@@ -72,7 +72,7 @@ public interface ScriptOperations {
 
 	/**
 	 * Checks {@link DB} for existence of {@link ServerSideJavaScript} with given name.
-	 * 
+	 *
 	 * @param scriptName must not be {@literal null} or empty.
 	 * @return false if no {@link ServerSideJavaScript} with given name exists.
 	 */
@@ -80,7 +80,7 @@ public interface ScriptOperations {
 
 	/**
 	 * Returns names of {@literal JavaScript} functions that can be called.
-	 * 
+	 *
 	 * @return empty {@link Set} if no scripts found.
 	 */
 	Set<String> getScriptNames();

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SessionCallback.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.lang.Nullable;
+
+/**
+ * Callback interface for executing operations within a {@link com.mongodb.session.ClientSession}.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ * @see com.mongodb.session.ClientSession
+ */
+@FunctionalInterface
+public interface SessionCallback<T> {
+
+	/**
+	 * Execute operations against a MongoDB instance via session bound {@link MongoOperations}. The session is inferred
+	 * directly into the operation so that no further interaction is necessary.
+	 * <p />
+	 * Please note that only Spring Data-specific abstractions like {@link MongoOperations#find(Query, Class)} and others
+	 * are enhanced with the {@link com.mongodb.session.ClientSession}. When obtaining plain MongoDB gateway objects like
+	 * {@link com.mongodb.client.MongoCollection} or {@link com.mongodb.client.MongoDatabase} via eg.
+	 * {@link MongoOperations#getCollection(String)} we leave responsibility for {@link com.mongodb.session.ClientSession}
+	 * again up to the caller.
+	 *
+	 * @param operations will never be {@literal null}.
+	 * @return can be {@literal null}.
+	 */
+	@Nullable
+	T doInSession(MongoOperations operations);
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SessionScoped.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import java.util.function.Consumer;
+
+import org.springframework.lang.Nullable;
+
+import com.mongodb.client.ClientSession;
+
+/**
+ * Gateway interface to execute {@link ClientSession} bound operations against MongoDB via a {@link SessionCallback}.
+ * <p />
+ * The very same bound {@link ClientSession} is used for all invocations of {@code execute} on the instance.
+ *
+ * @author Christoph Strobl
+ * @author Mark Paluch
+ * @since 2.1
+ */
+public interface SessionScoped {
+
+	/**
+	 * Executes the given {@link SessionCallback} within the {@link com.mongodb.session.ClientSession}.
+	 * <p/>
+	 * It is up to the caller to make sure the {@link com.mongodb.session.ClientSession} is {@link ClientSession#close()
+	 * closed} when done.
+	 *
+	 * @param action callback object that specifies the MongoDB action the callback action. Must not be {@literal null}.
+	 * @param <T> return type.
+	 * @return a result object returned by the action. Can be {@literal null}.
+	 */
+	@Nullable
+	default <T> T execute(SessionCallback<T> action) {
+		return execute(action, session -> {});
+	}
+
+	/**
+	 * Executes the given {@link SessionCallback} within the {@link com.mongodb.session.ClientSession}.
+	 * <p/>
+	 * It is up to the caller to make sure the {@link com.mongodb.session.ClientSession} is {@link ClientSession#close()
+	 * closed} when done.
+	 *
+	 * @param action callback object that specifies the MongoDB action the callback action. Must not be {@literal null}.
+	 * @param doFinally callback object that accepts {@link ClientSession} after invoking {@link SessionCallback}. This
+	 *          {@link Consumer} is guaranteed to be notified in any case (successful and exceptional outcome of
+	 *          {@link SessionCallback}).
+	 * @param <T> return type.
+	 * @return a result object returned by the action. Can be {@literal null}.
+	 */
+	@Nullable
+	<T> T execute(SessionCallback<T> action, Consumer<ClientSession> doFinally);
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SimpleMongoClientDbFactory.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2018-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core;
+
+import org.springframework.beans.factory.DisposableBean;
+
+import com.mongodb.ClientSessionOptions;
+import com.mongodb.ConnectionString;
+import com.mongodb.DB;
+import com.mongodb.client.ClientSession;
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+import com.mongodb.client.MongoDatabase;
+
+/**
+ * Factory to create {@link MongoDatabase} instances from a {@link MongoClient} instance.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+public class SimpleMongoClientDbFactory extends MongoDbFactorySupport<MongoClient> implements DisposableBean {
+
+	/**
+	 * Creates a new {@link SimpleMongoClientDbFactory} instance for the given {@code connectionString}.
+	 *
+	 * @param connectionString connection coordinates for a database connection. Must contain a database name and must not
+	 *          be {@literal null} or empty.
+	 * @see <a href="https://docs.mongodb.com/manual/reference/connection-string/">MongoDB Connection String reference</a>
+	 */
+	public SimpleMongoClientDbFactory(String connectionString) {
+		this(new ConnectionString(connectionString));
+	}
+
+	/**
+	 * Creates a new {@link SimpleMongoClientDbFactory} instance from the given {@link MongoClient}.
+	 *
+	 * @param connectionString connection coordinates for a database connection. Must contain also a database name and not
+	 *          be {@literal null}.
+	 */
+	public SimpleMongoClientDbFactory(ConnectionString connectionString) {
+		this(MongoClients.create(connectionString), connectionString.getDatabase(), true);
+	}
+
+	/**
+	 * Creates a new {@link SimpleMongoClientDbFactory} instance from the given {@link MongoClient}.
+	 *
+	 * @param mongoClient must not be {@literal null}.
+	 * @param databaseName must not be {@literal null} or empty.
+	 */
+	public SimpleMongoClientDbFactory(MongoClient mongoClient, String databaseName) {
+		this(mongoClient, databaseName, false);
+	}
+
+	/**
+	 * Creates a new {@link SimpleMongoClientDbFactory} instance from the given {@link MongoClient}.
+	 *
+	 * @param mongoClient must not be {@literal null}.
+	 * @param databaseName must not be {@literal null} or empty.
+	 * @param mongoInstanceCreated
+	 */
+	private SimpleMongoClientDbFactory(MongoClient mongoClient, String databaseName, boolean mongoInstanceCreated) {
+		super(mongoClient, databaseName, mongoInstanceCreated, new MongoExceptionTranslator());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getLegacyDb()
+	 */
+	@Override
+	public DB getLegacyDb() {
+
+		throw new UnsupportedOperationException(String.format(
+				"%s does not support legacy DBObject API! Please consider using SimpleMongoDbFactory for that purpose.",
+				MongoClient.class));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getSession(com.mongodb.ClientSessionOptions)
+	 */
+	@Override
+	public ClientSession getSession(ClientSessionOptions options) {
+		return getMongoClient().startSession(options);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.MongoDbFactoryBase#closeClient()
+	 */
+	@Override
+	protected void closeClient() {
+		getMongoClient().close();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.MongoDbFactoryBase#doGetMongoDatabase(java.lang.String)
+	 */
+	@Override
+	protected MongoDatabase doGetMongoDatabase(String dbName) {
+		return getMongoClient().getDatabase(dbName);
+	}
+}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SimpleMongoDbFactory.java

@@ -16,16 +16,14 @@
 package org.springframework.data.mongodb.core;
 
 import org.springframework.beans.factory.DisposableBean;
-import org.springframework.dao.DataAccessException;
-import org.springframework.dao.support.PersistenceExceptionTranslator;
-import org.springframework.data.mongodb.MongoDbFactory;
-import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 
+import com.mongodb.ClientSessionOptions;
 import com.mongodb.DB;
 import com.mongodb.MongoClient;
 import com.mongodb.MongoClientURI;
 import com.mongodb.WriteConcern;
+import com.mongodb.client.ClientSession;
+import com.mongodb.client.MongoCollection;
 import com.mongodb.client.MongoDatabase;
 
 /**
@@ -38,19 +36,12 @@ import com.mongodb.client.MongoDatabase;
  * @author George Moraitis
  * @author Mark Paluch
  */
-public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
-
-	private final MongoClient mongoClient;
-	private final String databaseName;
-	private final boolean mongoInstanceCreated;
-	private final PersistenceExceptionTranslator exceptionTranslator;
-
-	private @Nullable WriteConcern writeConcern;
+public class SimpleMongoDbFactory extends MongoDbFactorySupport<MongoClient> implements DisposableBean {
 
 	/**
 	 * Creates a new {@link SimpleMongoDbFactory} instance from the given {@link MongoClientURI}.
 	 *
-	 * @param uri must not be {@literal null}.
+	 * @param uri coordinates for a database connection. Must contain a database name and must not be {@literal null}.
 	 * @since 1.7
 	 */
 	public SimpleMongoDbFactory(MongoClientURI uri) {
@@ -61,7 +52,7 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * Creates a new {@link SimpleMongoDbFactory} instance from the given {@link MongoClient}.
 	 *
 	 * @param mongoClient must not be {@literal null}.
-	 * @param databaseName must not be {@literal null}.
+	 * @param databaseName must not be {@literal null} or empty.
 	 * @since 1.7
 	 */
 	public SimpleMongoDbFactory(MongoClient mongoClient, String databaseName) {
@@ -75,75 +66,42 @@ public class SimpleMongoDbFactory implements DisposableBean, MongoDbFactory {
 	 * @since 1.7
 	 */
 	private SimpleMongoDbFactory(MongoClient mongoClient, String databaseName, boolean mongoInstanceCreated) {
-
-		Assert.notNull(mongoClient, "MongoClient must not be null!");
-		Assert.hasText(databaseName, "Database name must not be empty!");
-		Assert.isTrue(databaseName.matches("[^/\\\\.$\"\\s]+"),
-				"Database name must not contain slashes, dots, spaces, quotes, or dollar signs!");
-
-		this.mongoClient = mongoClient;
-		this.databaseName = databaseName;
-		this.mongoInstanceCreated = mongoInstanceCreated;
-		this.exceptionTranslator = new MongoExceptionTranslator();
+		super(mongoClient, databaseName, mongoInstanceCreated, new MongoExceptionTranslator());
 	}
 
-	/**
-	 * Configures the {@link WriteConcern} to be used on the {@link DB} instance being created.
-	 *
-	 * @param writeConcern the writeConcern to set
-	 */
-	public void setWriteConcern(WriteConcern writeConcern) {
-		this.writeConcern = writeConcern;
-	}
-
-	/*
+	/* 
 	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb()
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getLegacyDb()
 	 */
-	public MongoDatabase getDb() throws DataAccessException {
-		return getDb(databaseName);
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.MongoDbFactory#getDb(java.lang.String)
-	 */
-	public MongoDatabase getDb(String dbName) throws DataAccessException {
-
-		Assert.hasText(dbName, "Database name must not be empty.");
-
-		MongoDatabase db = mongoClient.getDatabase(dbName);
-
-		if (writeConcern == null) {
-			return db;
-		}
-
-		return db.withWriteConcern(writeConcern);
-	}
-
-	/**
-	 * Clean up the Mongo instance if it was created by the factory itself.
-	 *
-	 * @see DisposableBean#destroy()
-	 */
-	public void destroy() throws Exception {
-		if (mongoInstanceCreated) {
-			mongoClient.close();
-		}
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.MongoDbFactory#getExceptionTranslator()
-	 */
-	@Override
-	public PersistenceExceptionTranslator getExceptionTranslator() {
-		return this.exceptionTranslator;
-	}
-
-	@SuppressWarnings("deprecation")
 	@Override
 	public DB getLegacyDb() {
-		return mongoClient.getDB(databaseName);
+		return getMongoClient().getDB(getDefaultDatabaseName());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.MongoDbFactory#getSession(com.mongodb.ClientSessionOptions)
+	 */
+	@Override
+	public ClientSession getSession(ClientSessionOptions options) {
+		return getMongoClient().startSession(options);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.MongoDbFactoryBase#closeClient()
+	 */
+	@Override
+	protected void closeClient() {
+		getMongoClient().close();
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.MongoDbFactoryBase#doGetMongoDatabase(java.lang.String)
+	 */
+	@Override
+	protected MongoDatabase doGetMongoDatabase(String dbName) {
+		return getMongoClient().getDatabase(dbName);
 	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/SimpleReactiveMongoDatabaseFactory.java

@@ -15,19 +15,25 @@
  */
 package org.springframework.data.mongodb.core;
 
-import java.net.UnknownHostException;
+import lombok.Value;
+import reactor.core.publisher.Mono;
 
+import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.support.PersistenceExceptionTranslator;
 import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
+import org.springframework.data.mongodb.SessionAwareMethodInterceptor;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
+import com.mongodb.ClientSessionOptions;
 import com.mongodb.ConnectionString;
 import com.mongodb.WriteConcern;
+import com.mongodb.reactivestreams.client.ClientSession;
 import com.mongodb.reactivestreams.client.MongoClient;
 import com.mongodb.reactivestreams.client.MongoClients;
+import com.mongodb.reactivestreams.client.MongoCollection;
 import com.mongodb.reactivestreams.client.MongoDatabase;
 
 /**
@@ -51,9 +57,8 @@ public class SimpleReactiveMongoDatabaseFactory implements DisposableBean, React
 	 * Creates a new {@link SimpleReactiveMongoDatabaseFactory} instance from the given {@link ConnectionString}.
 	 *
 	 * @param connectionString must not be {@literal null}.
-	 * @throws UnknownHostException
 	 */
-	public SimpleReactiveMongoDatabaseFactory(ConnectionString connectionString) throws UnknownHostException {
+	public SimpleReactiveMongoDatabaseFactory(ConnectionString connectionString) {
 		this(MongoClients.create(connectionString), connectionString.getDatabase(), true);
 	}
 
@@ -129,4 +134,106 @@ public class SimpleReactiveMongoDatabaseFactory implements DisposableBean, React
 	public PersistenceExceptionTranslator getExceptionTranslator() {
 		return this.exceptionTranslator;
 	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.ReactiveMongoDbFactory#getSession(com.mongodb.ClientSessionOptions)
+	 */
+	@Override
+	public Mono<ClientSession> getSession(ClientSessionOptions options) {
+		return Mono.from(mongo.startSession(options));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.ReactiveMongoDbFactory#withSession(com.mongodb.session.ClientSession)
+	 */
+	@Override
+	public ReactiveMongoDatabaseFactory withSession(ClientSession session) {
+		return new ClientSessionBoundMongoDbFactory(session, this);
+	}
+
+	/**
+	 * {@link ClientSession} bound {@link ReactiveMongoDatabaseFactory} decorating the database with a
+	 * {@link SessionAwareMethodInterceptor}.
+	 *
+	 * @author Christoph Strobl
+	 * @since 2.1
+	 */
+	@Value
+	static class ClientSessionBoundMongoDbFactory implements ReactiveMongoDatabaseFactory {
+
+		ClientSession session;
+		ReactiveMongoDatabaseFactory delegate;
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.ReactiveMongoDatabaseFactory#getMongoDatabase()
+		 */
+		@Override
+		public MongoDatabase getMongoDatabase() throws DataAccessException {
+			return decorateDatabase(delegate.getMongoDatabase());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.ReactiveMongoDatabaseFactory#getMongoDatabase(java.lang.String)
+		 */
+		@Override
+		public MongoDatabase getMongoDatabase(String dbName) throws DataAccessException {
+			return decorateDatabase(delegate.getMongoDatabase(dbName));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.ReactiveMongoDatabaseFactory#getExceptionTranslator()
+		 */
+		@Override
+		public PersistenceExceptionTranslator getExceptionTranslator() {
+			return delegate.getExceptionTranslator();
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.ReactiveMongoDatabaseFactory#getSession(com.mongodb.ClientSessionOptions)
+		 */
+		@Override
+		public Mono<ClientSession> getSession(ClientSessionOptions options) {
+			return delegate.getSession(options);
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.ReactiveMongoDatabaseFactory#withSession(com.mongodb.session.ClientSession)
+		 */
+		@Override
+		public ReactiveMongoDatabaseFactory withSession(ClientSession session) {
+			return delegate.withSession(session);
+		}
+
+		private MongoDatabase decorateDatabase(MongoDatabase database) {
+			return createProxyInstance(session, database, MongoDatabase.class);
+		}
+
+		private MongoDatabase proxyDatabase(com.mongodb.session.ClientSession session, MongoDatabase database) {
+			return createProxyInstance(session, database, MongoDatabase.class);
+		}
+
+		private MongoCollection proxyCollection(com.mongodb.session.ClientSession session, MongoCollection collection) {
+			return createProxyInstance(session, collection, MongoCollection.class);
+		}
+
+		private <T> T createProxyInstance(com.mongodb.session.ClientSession session, T target, Class<T> targetType) {
+
+			ProxyFactory factory = new ProxyFactory();
+			factory.setTarget(target);
+			factory.setInterfaces(targetType);
+			factory.setOpaque(true);
+
+			factory.addAdvice(new SessionAwareMethodInterceptor<>(session, target, ClientSession.class, MongoDatabase.class,
+					this::proxyDatabase, MongoCollection.class, this::proxyCollection));
+
+			return targetType.cast(factory.getProxy());
+		}
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/WriteConcernResolver.java

@@ -22,7 +22,7 @@ import com.mongodb.WriteConcern;
 /**
  * A strategy interface to determine the {@link WriteConcern} to use for a given {@link MongoAction}. Return the passed
  * in default {@link WriteConcern} (a property on {@link MongoAction}) if no determination can be made.
- * 
+ *
  * @author Mark Pollack
  * @author Oliver Gierke
  */
@@ -30,7 +30,7 @@ public interface WriteConcernResolver {
 
 	/**
 	 * Resolve the {@link WriteConcern} given the {@link MongoAction}.
-	 * 
+	 *
 	 * @param action describes the context of the Mongo action. Contains a default {@link WriteConcern} to use if one
 	 *          should not be resolved.
 	 * @return a {@link WriteConcern} based on the passed in {@link MongoAction} value, maybe {@literal null}.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AbstractAggregationExpression.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 
 import org.bson.Document;
+import org.springframework.data.mongodb.core.aggregation.Aggregation.SystemVariable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -92,6 +93,10 @@ abstract class AbstractAggregationExpression implements AggregationExpression {
 			return targetDocument;
 		}
 
+		if (value instanceof SystemVariable) {
+			return value.toString();
+		}
+
 		return value;
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/Aggregation.java

@@ -47,6 +47,7 @@ import org.springframework.util.Assert;
  * @author Christoph Strobl
  * @author Nikolay Bogdanov
  * @author Gustavo de Geus
+ * @author Jérôme Guyon
  * @since 1.3
  */
 public class Aggregation {
@@ -63,6 +64,33 @@ public class Aggregation {
 	 */
 	public static final String CURRENT = SystemVariable.CURRENT.toString();
 
+	/**
+	 * A variable to conditionally exclude a field. In a {@code $projection}, a field set to the variable
+	 * {@literal REMOVE} is excluded from the output.
+	 *
+	 * <pre>
+	 * <code>
+	 *
+	 * db.books.aggregate( [
+	 * {
+	 *     $project: {
+	 *         title: 1,
+	 *         "author.first": 1,
+	 *         "author.last" : 1,
+	 *         "author.middle": {
+	 *             $cond: {
+	 *                 if: { $eq: [ "", "$author.middle" ] },
+	 *                 then: "$$REMOVE",
+	 *                 else: "$author.middle"
+	 *             }
+	 *         }
+	 *     }
+	 * } ] )
+	 * </code>
+	 * </pre>
+	 */
+	public static final String REMOVE = SystemVariable.REMOVE.toString();
+
 	public static final AggregationOperationContext DEFAULT_CONTEXT = AggregationOperationRenderer.DEFAULT_CONTEXT;
 	public static final AggregationOptions DEFAULT_OPTIONS = newAggregationOptions().build();
 
@@ -177,6 +205,16 @@ public class Aggregation {
 		return aggregationOperations.indexOf(aggregationOperation) == aggregationOperations.size() - 1;
 	}
 
+	/**
+	 * Get the {@link AggregationOptions}.
+	 *
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	public AggregationOptions getOptions() {
+		return options;
+	}
+
 	/**
 	 * A pointer to the previous {@link AggregationOperation}.
 	 *
@@ -347,6 +385,28 @@ public class Aggregation {
 		return new SortOperation(Sort.by(direction, fields));
 	}
 
+	/**
+	 * Creates a new {@link SortByCountOperation} given {@literal groupByField}.
+	 *
+	 * @param field must not be {@literal null} or empty.
+	 * @return
+	 * @since 2.1
+	 */
+	public static SortByCountOperation sortByCount(String field) {
+		return new SortByCountOperation(field(field));
+	}
+
+	/**
+	 * Creates a new {@link SortByCountOperation} given {@link AggregationExpression group and sort expression}.
+	 *
+	 * @param groupAndSortExpression must not be {@literal null}.
+	 * @return
+	 * @since 2.1
+	 */
+	public static SortByCountOperation sortByCount(AggregationExpression groupAndSortExpression) {
+		return new SortByCountOperation(groupAndSortExpression);
+	}
+
 	/**
 	 * Creates a new {@link SkipOperation} skipping the given number of elements.
 	 *
@@ -575,21 +635,31 @@ public class Aggregation {
 	}
 
 	/**
-	 * Converts this {@link Aggregation} specification to a {@link Document}.
+	 * Renders this {@link Aggregation} specification to an aggregation pipeline returning a {@link List} of
+	 * {@link Document}.
 	 *
-	 * @param inputCollectionName the name of the input collection
-	 * @return the {@code Document} representing this aggregation
+	 * @return the aggregation pipeline representing this aggregation.
+	 * @since 2.1
+	 */
+	public List<Document> toPipeline(AggregationOperationContext rootContext) {
+		return AggregationOperationRenderer.toDocument(operations, rootContext);
+	}
+
+	/**
+	 * Converts this {@link Aggregation} specification to a {@link Document}.
+	 * <p/>
+	 * MongoDB requires as of 3.6 cursor-based aggregation. Use {@link #toPipeline(AggregationOperationContext)} to render
+	 * an aggregation pipeline.
+	 *
+	 * @param inputCollectionName the name of the input collection.
+	 * @return the {@code Document} representing this aggregation.
 	 */
 	public Document toDocument(String inputCollectionName, AggregationOperationContext rootContext) {
 
-		List<Document> operationDocuments = AggregationOperationRenderer.toDocument(operations, rootContext);
-
 		Document command = new Document("aggregate", inputCollectionName);
-		command.put("pipeline", operationDocuments);
+		command.put("pipeline", toPipeline(rootContext));
 
-		command = options.applyAndReturnPotentiallyChangedCommand(command);
-
-		return command;
+		return options.applyAndReturnPotentiallyChangedCommand(command);
 	}
 
 	/*
@@ -601,25 +671,16 @@ public class Aggregation {
 		return SerializationUtils.serializeToJsonSafely(toDocument("__collection__", DEFAULT_CONTEXT));
 	}
 
-	/**
-	 * Get {@link AggregationOptions} to apply.
-	 *
-	 * @return never {@literal null}.
-	 * @since 2.0.3
-	 */
-	public AggregationOptions getOptions() {
-		return options;
-	}
-
 	/**
 	 * Describes the system variables available in MongoDB aggregation framework pipeline expressions.
 	 *
 	 * @author Thomas Darimont
-	 * @see <a href="https://docs.mongodb.org/manual/reference/aggregation-variables">Aggregation Variables</a>
+	 * @author Christoph Strobl
+	 * @see <a href="https://docs.mongodb.com/manual/reference/aggregation-variables">Aggregation Variables</a>.
 	 */
 	enum SystemVariable {
 
-		ROOT, CURRENT;
+		ROOT, CURRENT, REMOVE;
 
 		private static final String PREFIX = "$$";
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationFunctionExpressions.java

@@ -24,7 +24,7 @@ import org.springframework.util.Assert;
 
 /**
  * An enum of supported {@link AggregationExpression}s in aggregation pipeline stages.
- * 
+ *
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Christoph Strobl
@@ -39,7 +39,7 @@ public enum AggregationFunctionExpressions {
 
 	/**
 	 * Returns an {@link AggregationExpression} build from the current {@link Enum} name and the given parameters.
-	 * 
+	 *
 	 * @param parameters must not be {@literal null}
 	 * @return
 	 */
@@ -51,7 +51,7 @@ public enum AggregationFunctionExpressions {
 
 	/**
 	 * An {@link AggregationExpression} representing a function call.
-	 * 
+	 *
 	 * @author Thomas Darimont
 	 * @author Oliver Gierke
 	 * @since 1.7
@@ -63,7 +63,7 @@ public enum AggregationFunctionExpressions {
 
 		/**
 		 * Creates a new {@link FunctionExpression} for the given name and values.
-		 * 
+		 *
 		 * @param name must not be {@literal null} or empty.
 		 * @param values must not be {@literal null}.
 		 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOperation.java

@@ -19,7 +19,7 @@ import org.bson.Document;
 
 /**
  * Represents one single operation in an aggregation pipeline.
- * 
+ *
  * @author Sebastian Herold
  * @author Thomas Darimont
  * @author Oliver Gierke
@@ -31,7 +31,7 @@ public interface AggregationOperation {
 	/**
 	 * Turns the {@link AggregationOperation} into a {@link Document} by using the given
 	 * {@link AggregationOperationContext}.
-	 * 
+	 *
 	 * @return the Document
 	 */
 	Document toDocument(AggregationOperationContext context);

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOperationContext.java

@@ -20,7 +20,7 @@ import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldRefe
 
 /**
  * The context for an {@link AggregationOperation}.
- * 
+ *
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @since 1.3
@@ -29,7 +29,7 @@ public interface AggregationOperationContext {
 
 	/**
 	 * Returns the mapped {@link Document}, potentially converting the source considering mapping metadata etc.
-	 * 
+	 *
 	 * @param document will never be {@literal null}.
 	 * @return must not be {@literal null}.
 	 */
@@ -38,7 +38,7 @@ public interface AggregationOperationContext {
 	/**
 	 * Returns a {@link FieldReference} for the given field or {@literal null} if the context does not expose the given
 	 * field.
-	 * 
+	 *
 	 * @param field must not be {@literal null}.
 	 * @return
 	 */
@@ -47,7 +47,7 @@ public interface AggregationOperationContext {
 	/**
 	 * Returns the {@link FieldReference} for the field with the given name or {@literal null} if the context does not
 	 * expose a field with the given name.
-	 * 
+	 *
 	 * @param name must not be {@literal null} or empty.
 	 * @return
 	 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationOptions.java

@@ -147,6 +147,7 @@ public class AggregationOptions {
 	 * @return the batch size or {@literal null}.
 	 * @since 2.0
 	 */
+	@Nullable
 	public Integer getCursorBatchSize() {
 
 		if (cursor.filter(val -> val.containsKey(BATCH_SIZE)).isPresent()) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationSpELExpression.java

@@ -33,7 +33,7 @@ import org.springframework.util.Assert;
  * expressionOf("cond(a >= 42, 'answer', 'no-answer')");
  * </pre>
  * </code>
- * 
+ *
  * @author Christoph Strobl
  * @author Mark Paluch
  * @see SpelExpressionTransformer