diff --git a/spring-core-4/pom.xml b/spring-core-4/pom.xml
index 53f7ca6912..fbec5ea9eb 100644
--- a/spring-core-4/pom.xml
+++ b/spring-core-4/pom.xml
@@ -24,6 +24,16 @@
             <artifactId>spring-core</artifactId>
             <version>${spring.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-expression</artifactId>
+            <version>${spring.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>28.2-jre</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-test</artifactId>
@@ -42,6 +52,18 @@
             <version>${junit-jupiter.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>4.0.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>2.9.1</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -60,4 +82,4 @@
         <spring.boot.version>2.2.2.RELEASE</spring.boot.version>
     </properties>
 
-</project>
\ No newline at end of file
+</project>
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/GlobalEventBus.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/GlobalEventBus.java
new file mode 100644
index 0000000000..8b95ea7c6f
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/GlobalEventBus.java
@@ -0,0 +1,39 @@
+package com.baeldung.postprocessor;
+
+import com.google.common.eventbus.AsyncEventBus;
+import com.google.common.eventbus.EventBus;
+
+import java.util.concurrent.Executors;
+
+@SuppressWarnings("ALL")
+public final class GlobalEventBus {
+
+    public static final String GLOBAL_EVENT_BUS_EXPRESSION = "T(com.baeldung.postprocessor.GlobalEventBus).getEventBus()";
+
+    private static final String IDENTIFIER = "global-event-bus";
+
+    private static final GlobalEventBus GLOBAL_EVENT_BUS = new GlobalEventBus();
+
+    private final EventBus eventBus = new AsyncEventBus(IDENTIFIER, Executors.newCachedThreadPool());
+
+    private GlobalEventBus() {
+    }
+
+    public static GlobalEventBus getInstance() {
+        return GlobalEventBus.GLOBAL_EVENT_BUS;
+    }
+
+    public static EventBus getEventBus() {
+        return GlobalEventBus.GLOBAL_EVENT_BUS.eventBus;
+    }
+
+    public static void subscribe(Object obj) {
+        getEventBus().register(obj);
+    }
+    public static void unsubscribe(Object obj) {
+        getEventBus().unregister(obj);
+    }
+    public static void post(Object event) {
+        getEventBus().post(event);
+    }
+}
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanFactoryPostProcessor.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanFactoryPostProcessor.java
new file mode 100644
index 0000000000..fba31fde6a
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanFactoryPostProcessor.java
@@ -0,0 +1,63 @@
+package com.baeldung.postprocessor;
+
+import com.google.common.eventbus.EventBus;
+
+import java.util.Iterator;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.aop.framework.Advised;
+import org.springframework.aop.support.AopUtils;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.FatalBeanException;
+import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.expression.Expression;
+import org.springframework.expression.ExpressionException;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+
+@SuppressWarnings("ALL")
+public class GuavaEventBusBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
+
+    private final Logger logger = LoggerFactory.getLogger(this.getClass());
+    private final SpelExpressionParser expressionParser = new SpelExpressionParser();
+
+    @Override
+    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
+        for (Iterator<String> names = beanFactory.getBeanNamesIterator(); names.hasNext(); ) {
+            Object proxy = this.getTargetObject(beanFactory.getBean(names.next()));
+            final Subscriber annotation = AnnotationUtils.getAnnotation(proxy.getClass(), Subscriber.class);
+            if (annotation == null)
+                continue;
+            this.logger.info("{}: processing bean of type {} during initialization", this.getClass().getSimpleName(),
+              proxy.getClass().getName());
+            final String annotationValue = annotation.value();
+            try {
+                final Expression expression = this.expressionParser.parseExpression(annotationValue);
+                final Object value = expression.getValue();
+                if (!(value instanceof EventBus)) {
+                    this.logger.error("{}: expression {} did not evaluate to an instance of EventBus for bean of type {}",
+                      this.getClass().getSimpleName(), annotationValue, proxy.getClass().getSimpleName());
+                    return;
+                }
+                final EventBus eventBus = (EventBus)value;
+                eventBus.register(proxy);
+            } catch (ExpressionException ex) {
+                this.logger.error("{}: unable to parse/evaluate expression {} for bean of type {}", this.getClass().getSimpleName(),
+                  annotationValue, proxy.getClass().getName());
+            }
+        }
+    }
+
+    private Object getTargetObject(Object proxy) throws BeansException {
+        if (AopUtils.isJdkDynamicProxy(proxy)) {
+            try {
+                return ((Advised)proxy).getTargetSource().getTarget();
+            } catch (Exception e) {
+                throw new FatalBeanException("Error getting target of JDK proxy", e);
+            }
+        }
+        return proxy;
+    }
+}
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanPostProcessor.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanPostProcessor.java
new file mode 100644
index 0000000000..677c839444
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/GuavaEventBusBeanPostProcessor.java
@@ -0,0 +1,87 @@
+package com.baeldung.postprocessor;
+
+import com.google.common.eventbus.EventBus;
+
+import java.util.function.BiConsumer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.aop.framework.Advised;
+import org.springframework.aop.support.AopUtils;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.FatalBeanException;
+import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.expression.Expression;
+import org.springframework.expression.ExpressionException;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+
+/**
+ * A {@link DestructionAwareBeanPostProcessor} which registers/un-registers subscribers to a Guava {@link EventBus}. The class must
+ * be annotated with {@link Subscriber} and each subscribing method must be annotated with
+ * {@link com.google.common.eventbus.Subscribe}.
+ */
+@SuppressWarnings("ALL")
+public class GuavaEventBusBeanPostProcessor implements DestructionAwareBeanPostProcessor {
+
+    private final Logger logger = LoggerFactory.getLogger(this.getClass());
+    private final SpelExpressionParser expressionParser = new SpelExpressionParser();
+
+    @Override
+    public void postProcessBeforeDestruction(final Object bean, final String beanName) throws BeansException {
+        this.process(bean, EventBus::unregister, "destruction");
+    }
+
+    @Override
+    public boolean requiresDestruction(Object bean) {
+        return true;
+    }
+
+    @Override
+    public Object postProcessBeforeInitialization(final Object bean, final String beanName) throws BeansException {
+        return bean;
+    }
+
+    @Override
+    public Object postProcessAfterInitialization(final Object bean, final String beanName) throws BeansException {
+        this.process(bean, EventBus::register, "initialization");
+        return bean;
+    }
+
+    private void process(final Object bean, final BiConsumer<EventBus, Object> consumer, final String action) {
+        Object proxy = this.getTargetObject(bean);
+        final Subscriber annotation = AnnotationUtils.getAnnotation(proxy.getClass(), Subscriber.class);
+        if (annotation == null)
+            return;
+        this.logger.info("{}: processing bean of type {} during {}", this.getClass().getSimpleName(), proxy.getClass().getName(),
+          action);
+        final String annotationValue = annotation.value();
+        try {
+            final Expression expression = this.expressionParser.parseExpression(annotationValue);
+            final Object value = expression.getValue();
+            if (!(value instanceof EventBus)) {
+                this.logger.error("{}: expression {} did not evaluate to an instance of EventBus for bean of type {}",
+                  this.getClass().getSimpleName(), annotationValue, proxy.getClass().getSimpleName());
+                return;
+            }
+            final EventBus eventBus = (EventBus)value;
+            consumer.accept(eventBus, proxy);
+        } catch (ExpressionException ex) {
+            this.logger.error("{}: unable to parse/evaluate expression {} for bean of type {}", this.getClass().getSimpleName(),
+              annotationValue, proxy.getClass().getName());
+        }
+    }
+
+    private Object getTargetObject(Object proxy) throws BeansException {
+        if (AopUtils.isJdkDynamicProxy(proxy)) {
+            try {
+                return ((Advised)proxy).getTargetSource().getTarget();
+            } catch (Exception e) {
+                throw new FatalBeanException("Error getting target of JDK proxy", e);
+            }
+        }
+        return proxy;
+    }
+}
+
+
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTrade.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTrade.java
new file mode 100644
index 0000000000..7711cf7101
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTrade.java
@@ -0,0 +1,34 @@
+package com.baeldung.postprocessor;
+
+import java.util.Date;
+
+public class StockTrade {
+
+    private final String symbol;
+    private final int quantity;
+    private final double price;
+    private final Date tradeDate;
+
+    public StockTrade(String symbol, int quantity, double price, Date tradeDate) {
+        this.symbol = symbol;
+        this.quantity = quantity;
+        this.price = price;
+        this.tradeDate = tradeDate;
+    }
+
+    public String getSymbol() {
+        return this.symbol;
+    }
+
+    public int getQuantity() {
+        return this.quantity;
+    }
+
+    public double getPrice() {
+        return this.price;
+    }
+
+    public Date getTradeDate() {
+        return this.tradeDate;
+    }
+}
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradeListener.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradeListener.java
new file mode 100644
index 0000000000..bf34d66f24
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradeListener.java
@@ -0,0 +1,7 @@
+package com.baeldung.postprocessor;
+
+@FunctionalInterface
+public interface StockTradeListener {
+
+    void stockTradePublished(StockTrade trade);
+}
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradePublisher.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradePublisher.java
new file mode 100644
index 0000000000..bf339872d9
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/StockTradePublisher.java
@@ -0,0 +1,36 @@
+package com.baeldung.postprocessor;
+
+import com.google.common.eventbus.AllowConcurrentEvents;
+import com.google.common.eventbus.Subscribe;
+
+import java.util.HashSet;
+import java.util.Set;
+
+@Subscriber
+public class StockTradePublisher {
+
+    private final Set<StockTradeListener> stockTradeListeners = new HashSet<>();
+
+    public void addStockTradeListener(StockTradeListener listener) {
+        synchronized (this.stockTradeListeners) {
+            this.stockTradeListeners.add(listener);
+        }
+    }
+
+    public void removeStockTradeListener(StockTradeListener listener) {
+        synchronized (this.stockTradeListeners) {
+            this.stockTradeListeners.remove(listener);
+        }
+    }
+
+    @Subscribe
+    @AllowConcurrentEvents
+    private void handleNewStockTradeEvent(StockTrade trade) {
+        // publish to DB, send to PubNub, whatever you want here
+        final Set<StockTradeListener> listeners;
+        synchronized (this.stockTradeListeners) {
+            listeners = new HashSet<>(this.stockTradeListeners);
+        }
+        listeners.forEach(li -> li.stockTradePublished(trade));
+    }
+}
diff --git a/spring-core-4/src/main/java/com/baeldung/postprocessor/Subscriber.java b/spring-core-4/src/main/java/com/baeldung/postprocessor/Subscriber.java
new file mode 100644
index 0000000000..bef38333d6
--- /dev/null
+++ b/spring-core-4/src/main/java/com/baeldung/postprocessor/Subscriber.java
@@ -0,0 +1,21 @@
+package com.baeldung.postprocessor;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * An annotation which indicates which Guava {@link com.google.common.eventbus.EventBus} a Spring bean wishes to subscribe to.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+@Inherited
+public @interface Subscriber {
+
+    /**
+     * A SpEL expression which selects the {@link com.google.common.eventbus.EventBus}.
+     */
+    String value() default GlobalEventBus.GLOBAL_EVENT_BUS_EXPRESSION;
+}
diff --git a/spring-core-4/src/test/java/com/baeldung/postprocessor/PostProcessorConfiguration.java b/spring-core-4/src/test/java/com/baeldung/postprocessor/PostProcessorConfiguration.java
new file mode 100644
index 0000000000..b28e36663a
--- /dev/null
+++ b/spring-core-4/src/test/java/com/baeldung/postprocessor/PostProcessorConfiguration.java
@@ -0,0 +1,23 @@
+package com.baeldung.postprocessor;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class PostProcessorConfiguration {
+
+    @Bean
+    public GlobalEventBus eventBus() {
+        return GlobalEventBus.getInstance();
+    }
+
+    @Bean
+    public GuavaEventBusBeanPostProcessor eventBusBeanPostProcessor() {
+        return new GuavaEventBusBeanPostProcessor();
+    }
+
+    @Bean
+    public StockTradePublisher stockTradePublisher() {
+        return new StockTradePublisher();
+    }
+}
diff --git a/spring-core-4/src/test/java/com/baeldung/postprocessor/StockTradeIntegrationTest.java b/spring-core-4/src/test/java/com/baeldung/postprocessor/StockTradeIntegrationTest.java
new file mode 100644
index 0000000000..ae3cd968dc
--- /dev/null
+++ b/spring-core-4/src/test/java/com/baeldung/postprocessor/StockTradeIntegrationTest.java
@@ -0,0 +1,46 @@
+package com.baeldung.postprocessor;
+
+import java.time.Duration;
+import java.util.Date;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = {PostProcessorConfiguration.class})
+public class StockTradeIntegrationTest {
+
+    @Autowired
+    private StockTradePublisher stockTradePublisher;
+
+    @Test
+    public void givenValidConfig_whenTradePublished_thenTradeReceived() {
+        Date tradeDate = new Date();
+        StockTrade stockTrade = new StockTrade("AMZN", 100, 2483.52d, tradeDate);
+        AtomicBoolean assertionsPassed = new AtomicBoolean(false);
+        StockTradeListener listener = trade -> assertionsPassed.set(this.verifyExact(stockTrade, trade));
+        this.stockTradePublisher.addStockTradeListener(listener);
+        try {
+            GlobalEventBus.post(stockTrade);
+            await().atMost(Duration.ofSeconds(2L))
+              .untilAsserted(() -> assertThat(assertionsPassed.get()).isTrue());
+        } finally {
+            this.stockTradePublisher.removeStockTradeListener(listener);
+        }
+    }
+
+    private boolean verifyExact(StockTrade stockTrade, StockTrade trade) {
+        return Objects.equals(stockTrade.getSymbol(), trade.getSymbol())
+          && Objects.equals(stockTrade.getTradeDate(), trade.getTradeDate())
+          && stockTrade.getQuantity() == trade.getQuantity()
+          && stockTrade.getPrice() == trade.getPrice();
+    }
+}