refactor and extend the example

.gitignore

@@ -3,3 +3,4 @@
 *.iws
 *.iml
 *.ipr
+target/

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleController.java

@@ -1,41 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.api;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PathVariable;
-import org.springframework.web.bind.annotation.PostMapping;
-import org.springframework.web.bind.annotation.RequestBody;
-import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RestController;
-
-@RestController
-@RequestMapping("articles")
-class ArticleController {
-
-    private final Logger log = LoggerFactory.getLogger(ArticleController.class);
-
-    private final ArticleService service;
-
-    ArticleController(final ArticleService service) {
-        this.service = service;
-    }
-
-    @GetMapping("{articleId}")
-    ArticleResponse get(@PathVariable("articleId") final String articleId) {
-        log.info(">>> HTTP GET Request: retrieve an article with id: \"{}\"", articleId);
-        final ArticleResponse articleResponse = service.get(articleId);
-        log.info("<<< HTTP GET Response: article: \"{}\", successfully retrieved", articleResponse.title());
-        return articleResponse;
-    }
-
-    @PostMapping
-    ArticleIdResponse create(@RequestBody final ArticleRequest articleRequest) {
-        log.info(">>> HTTP POST Request: create an article: \"{}\"", articleRequest.title().value());
-        final ArticleIdResponse articleIdResponse = service.create(articleRequest);
-        log.info("<<< HTTP POST Response: article with id: \"{}\", successfully created", articleIdResponse.id());
-        return articleIdResponse;
-    }
-
-
-}

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleEndpoint.java

@@ -0,0 +1,30 @@
+package tech.allegro.hexagon.articles.adapters.api;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("articles")
+class ArticleEndpoint {
+
+    private final ArticleFacade articles;
+
+    ArticleEndpoint(ArticleFacade articles) {
+        this.articles = articles;
+    }
+
+    @GetMapping("{articleId}")
+    ArticleResponse get(@PathVariable("articleId") final String articleId) {
+        return articles.get(articleId);
+    }
+
+    @PostMapping
+    ArticleIdResponse create(@RequestBody final ArticleRequest articleRequest) {
+        return articles.create(articleRequest);
+    }
+
+}

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleFacade.java

@@ -0,0 +1,26 @@
+package tech.allegro.hexagon.articles.adapters.api;
+
+import org.springframework.stereotype.Component;
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.model.ArticleId;
+import tech.allegro.hexagon.articles.domain.ports.ArticleService;
+
+@Component
+class ArticleFacade {
+
+    private final ArticleService articleService;
+
+    ArticleFacade(final ArticleService articleService) {
+        this.articleService = articleService;
+    }
+
+    ArticleResponse get(final String articleId) {
+        final Article article = articleService.get(ArticleId.of(articleId));
+        return ArticleResponse.of(article);
+    }
+
+    ArticleIdResponse create(final ArticleRequest articleRequest) {
+        final ArticleId articleId = articleService.create(articleRequest.authorId(), articleRequest.title(), articleRequest.content());
+        return ArticleIdResponse.of(articleId);
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleIdResponse.java

@@ -1,22 +1,23 @@
 package tech.allegro.hexagon.articles.adapters.api;
 
-import tech.allegro.hexagon.articles.domain.model.ArticleId;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import tech.allegro.hexagon.articles.domain.model.ArticleId;
 
 class ArticleIdResponse {
+
     private final String id;
 
     private ArticleIdResponse(final String id) {
         this.id = id;
     }
 
-    @JsonProperty("id")
-    public String id() {
-        return id;
-    }
-
-    public static ArticleIdResponse of(final ArticleId articleId) {
+    static ArticleIdResponse of(final ArticleId articleId) {
         return new ArticleIdResponse(articleId.value());
     }
 
+    @JsonProperty("id")
+    String id() {
+        return id;
+    }
+
 }

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleRequest.java

@@ -1,9 +1,9 @@
 package tech.allegro.hexagon.articles.adapters.api;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
 import tech.allegro.hexagon.articles.domain.model.AuthorId;
 import tech.allegro.hexagon.articles.domain.model.Content;
 import tech.allegro.hexagon.articles.domain.model.Title;
-import com.fasterxml.jackson.annotation.JsonProperty;
 
 class ArticleRequest {
     private final String title;
@@ -17,15 +17,15 @@ class ArticleRequest {
     }
 
 
-    public Title title() {
+    Title title() {
         return Title.of(title);
     }
 
-    public Content content() {
+    Content content() {
         return Content.of(content);
     }
 
-    public AuthorId authorId() {
+    AuthorId authorId() {
         return AuthorId.of(authorId);
     }
 

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleResponse.java

@@ -1,7 +1,7 @@
 package tech.allegro.hexagon.articles.adapters.api;
 
-import tech.allegro.hexagon.articles.domain.model.Article;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import tech.allegro.hexagon.articles.domain.model.Article;
 
 class ArticleResponse {
     private final String id;
@@ -24,22 +24,22 @@ class ArticleResponse {
     }
 
     @JsonProperty("id")
-    public String id() {
+    String id() {
         return id;
     }
 
     @JsonProperty("title")
-    public String title() {
+    String title() {
         return title;
     }
 
     @JsonProperty("content")
-    public String content() {
+    String content() {
         return content;
     }
 
     @JsonProperty("authorName")
-    public String authorName() {
+    String authorName() {
         return authorName;
     }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/api/ArticleService.java

@@ -1,24 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.api;
-
-import tech.allegro.hexagon.articles.domain.ArticleFacade;
-import tech.allegro.hexagon.articles.domain.model.ArticleId;
-import org.springframework.stereotype.Component;
-
-@Component
-class ArticleService {
-
-    private final ArticleFacade articleFacade;
-
-    ArticleService(final ArticleFacade articleFacade) {
-        this.articleFacade = articleFacade;
-    }
-
-    ArticleResponse get(final String articleId) {
-        return ArticleResponse.of(articleFacade.get(ArticleId.of(articleId)));
-    }
-
-    ArticleIdResponse create(final ArticleRequest articleRequest) {
-        final ArticleId articleId = articleFacade.create(articleRequest.authorId(), articleRequest.title(), articleRequest.content());
-        return ArticleIdResponse.of(articleId);
-    }
-}

src/main/java/tech/allegro/hexagon/articles/adapters/articledb/ArticleDatabaseModel.java

@@ -1,7 +1,125 @@
 package tech.allegro.hexagon.articles.adapters.articledb;
 
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.model.ArticleId;
+import tech.allegro.hexagon.articles.domain.model.Author;
+import tech.allegro.hexagon.articles.domain.model.AuthorId;
+import tech.allegro.hexagon.articles.domain.model.Content;
+import tech.allegro.hexagon.articles.domain.model.PersonName;
+import tech.allegro.hexagon.articles.domain.model.Title;
+
+import java.time.ZonedDateTime;
+import java.util.UUID;
+
 class ArticleDatabaseModel {
-    /**
-     * Database model implementation comes here
-     */
+
+    private final UUID id;
+    private final String title;
+    private final String content;
+    private final long version;
+    private final ZonedDateTime createdAt;
+    private final String authorId;
+    private final String authorName;
+
+    private ArticleDatabaseModel(final UUID id,
+                                 final String title,
+                                 final String content,
+                                 final String authorId,
+                                 final long version,
+                                 final ZonedDateTime createdAt,
+                                 final String authorName) {
+        this.id = id;
+        this.title = title;
+        this.content = content;
+        this.authorId = authorId;
+        this.version = version;
+        this.createdAt = createdAt;
+        this.authorName = authorName;
+    }
+
+    @Override
+    public String toString() {
+        return title;
+    }
+
+    Article toDomain() {
+        return Article.article()
+                .withId(ArticleId.of(id.toString()))
+                .withAuthor(Author
+                        .author()
+                        .withId(AuthorId.of(authorId))
+                        .withName(PersonName.of(authorName))
+                        .build())
+                .withTitle(Title.of(title))
+                .withContent(Content.of(content))
+                .build();
+    }
+
+    static ArticleDatabaseModel of(final Author author, final Title title, final Content content) {
+        return articleDatabaseModel()
+                .withId(UUID.randomUUID())
+                .withVersion(0)
+                .withCreatedAt(ZonedDateTime.now())
+                .withAuthorId(author.id().value())
+                .withAuthorName(author.name().value())
+                .withTitle(title.value())
+                .withContent(content.value())
+                .build();
+    }
+
+    static ArticleDatabaseModelBuilder articleDatabaseModel() {
+        return new ArticleDatabaseModelBuilder();
+    }
+
+    static final class ArticleDatabaseModelBuilder {
+        private UUID id;
+        private String title;
+        private String content;
+        private long version;
+        private ZonedDateTime createdAt;
+        private String authorId;
+        private String authorName;
+
+        private ArticleDatabaseModelBuilder() {
+        }
+
+        ArticleDatabaseModelBuilder withId(UUID id) {
+            this.id = id;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withTitle(String title) {
+            this.title = title;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withContent(String content) {
+            this.content = content;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withVersion(long version) {
+            this.version = version;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withCreatedAt(ZonedDateTime createdAt) {
+            this.createdAt = createdAt;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withAuthorId(String authorId) {
+            this.authorId = authorId;
+            return this;
+        }
+
+        ArticleDatabaseModelBuilder withAuthorName(String authorName) {
+            this.authorName = authorName;
+            return this;
+        }
+
+        ArticleDatabaseModel build() {
+            return new ArticleDatabaseModel(id, title, content, authorId, version, createdAt, authorName);
+        }
+    }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/articledb/DbArticleRepository.java

@@ -1,56 +1,42 @@
 package tech.allegro.hexagon.articles.adapters.articledb;
 
+import org.springframework.stereotype.Component;
 import tech.allegro.hexagon.articles.domain.model.Article;
 import tech.allegro.hexagon.articles.domain.model.ArticleId;
 import tech.allegro.hexagon.articles.domain.model.Author;
-import tech.allegro.hexagon.articles.domain.model.AuthorId;
 import tech.allegro.hexagon.articles.domain.model.Content;
-import tech.allegro.hexagon.articles.domain.model.PersonName;
 import tech.allegro.hexagon.articles.domain.model.Title;
 import tech.allegro.hexagon.articles.domain.ports.ArticleRepository;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
 
 import java.util.UUID;
 
+import static tech.allegro.hexagon.articles.adapters.articledb.ArticleDatabaseModel.articleDatabaseModel;
+import static tech.allegro.hexagon.articles.adapters.articledb.ArticleDatabaseModel.of;
+
 @Component
 class DbArticleRepository implements ArticleRepository {
 
-    private final Logger log = LoggerFactory.getLogger(DbArticleRepository.class);
-
-
     @Override
     public Article save(final Author author, final Title title, final Content content) {
         /**
-         * Database integration implementation using {@link ArticleDatabaseModel} comes here
+         * Database integration implementation comes here
          */
-        final String articleId = UUID.randomUUID().toString();
-        log.info("Article: \"{}\" persisted", title.value());
-        return Article.article()
-                .withId(ArticleId.of(articleId))
-                .withAuthor(author)
-                .withTitle(title)
-                .withContent(content)
-                .build();
+        final ArticleDatabaseModel entity = of(author, title, content);
+        return entity.toDomain();
     }
 
     @Override
     public Article get(final ArticleId id) {
         /**
-         * Database integration implementation using {@link ArticleDatabaseModel} comes here
+         * Database integration implementation comes here
          */
-        final Title title = Title.of("Hexagonal Architecture");
-        log.info("Article \"{}\" fetched", title.value());
-        return Article.article()
-                .withId(id)
-                .withAuthor(Author
-                        .author()
-                        .withId(AuthorId.of(UUID.randomUUID().toString()))
-                        .withName(PersonName.of("William Shakespeare"))
-                        .build())
-                .withTitle(title)
-                .withContent(Content.of("Lorem ipsum"))
+        final ArticleDatabaseModel entity = articleDatabaseModel()
+                .withId(UUID.fromString(id.value()))
+                .withAuthorName("William Shakespeare")
+                .withAuthorId("928467")
+                .withTitle("Hexagonal Architecture")
+                .withContent("Lorem ipsum")
                 .build();
+        return entity.toDomain();
     }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/authorservice/AuthorExternalModel.java

@@ -1,7 +1,65 @@
 package tech.allegro.hexagon.articles.adapters.authorservice;
 
+import tech.allegro.hexagon.articles.domain.model.Author;
+import tech.allegro.hexagon.articles.domain.model.AuthorId;
+import tech.allegro.hexagon.articles.domain.model.PersonName;
+
 class AuthorExternalModel {
-    /**
-     * External author service model implementation comes here
-     */
+    private final long id;
+    private final String firstName;
+    private final String lastName;
+
+    private AuthorExternalModel(final long id, final String firstName, final String lastName) {
+        this.id = id;
+        this.firstName = firstName;
+        this.lastName = lastName;
+    }
+
+    Author toDomain() {
+        return Author.author()
+                .withId(AuthorId.of(String.valueOf(id)))
+                .withName(PersonName.of(fullName()))
+                .build();
+    }
+
+    private String fullName() {
+        return String.format("%s %s", firstName, lastName);
+    }
+
+    @Override
+    public String toString() {
+        return fullName();
+    }
+
+    static AuthorExternalModelBuilder authorExternalModel() {
+        return new AuthorExternalModelBuilder();
+    }
+
+    static final class AuthorExternalModelBuilder {
+        private long id;
+        private String firstName;
+        private String lastName;
+
+        private AuthorExternalModelBuilder() {
+        }
+
+        AuthorExternalModelBuilder withId(long id) {
+            this.id = id;
+            return this;
+        }
+
+        AuthorExternalModelBuilder withFirstName(String firstName) {
+            this.firstName = firstName;
+            return this;
+        }
+
+        AuthorExternalModelBuilder withLastName(String lastName) {
+            this.lastName = lastName;
+            return this;
+        }
+
+        AuthorExternalModel build() {
+            return new AuthorExternalModel(id, firstName, lastName);
+        }
+    }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/authorservice/ExternalServiceClientAuthorRepository.java

@@ -1,27 +1,26 @@
 package tech.allegro.hexagon.articles.adapters.authorservice;
 
+import org.springframework.stereotype.Component;
 import tech.allegro.hexagon.articles.domain.model.Author;
 import tech.allegro.hexagon.articles.domain.model.AuthorId;
-import tech.allegro.hexagon.articles.domain.model.PersonName;
 import tech.allegro.hexagon.articles.domain.ports.AuthorRepository;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
+
+import static tech.allegro.hexagon.articles.adapters.authorservice.AuthorExternalModel.authorExternalModel;
 
 @Component
 class ExternalServiceClientAuthorRepository implements AuthorRepository {
-    private final Logger log = LoggerFactory.getLogger(ExternalServiceClientAuthorRepository.class);
+
 
     @Override
     public Author get(final AuthorId authorId) {
         /**
          * external author service integration implementation comes here
          */
-        log.info("Author: \"William Shakespeare\" fetched", authorId.value());
-        return Author
-                .author()
-                .withId(authorId)
-                .withName(PersonName.of("William Shakespeare"))
+        final AuthorExternalModel author = authorExternalModel()
+                .withId(928467)
+                .withFirstName("William")
+                .withLastName("Shakespeare")
                 .build();
+        return author.toDomain();
     }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/config/ArticleConfig.java

@@ -1,26 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.config;
-
-import tech.allegro.hexagon.articles.domain.ArticleFacade;
-import tech.allegro.hexagon.articles.domain.ports.ArticleAuthorNotifier;
-import tech.allegro.hexagon.articles.domain.ports.ArticleEventPublisher;
-import tech.allegro.hexagon.articles.domain.ports.ArticleRepository;
-import tech.allegro.hexagon.articles.domain.ports.AuthorRepository;
-import tech.allegro.hexagon.articles.domain.ports.SocialMediaPublisher;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-
-import java.util.List;
-
-@Configuration
-class ArticleConfig {
-
-    @Bean
-    ArticleFacade articleFacade(final ArticleRepository articleRepository,
-                                final AuthorRepository authorRepository,
-                                final ArticleEventPublisher eventPublisher,
-                                final List<SocialMediaPublisher> socialMediaPublishers,
-                                final List<ArticleAuthorNotifier> articleAuthorNotifiers) {
-        return new ArticleFacade(eventPublisher, articleRepository, authorRepository, socialMediaPublishers, articleAuthorNotifiers);
-    }
-
-}

src/main/java/tech/allegro/hexagon/articles/adapters/eventbus/ArticleCreatedEvent.java

@@ -1,7 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.eventbus;
-
-class ArticleCreatedEvent {
-    /**
-     * Message broker model implementation comes here
-     */
-}

src/main/java/tech/allegro/hexagon/articles/adapters/eventbus/ArticleRetrievedEvent.java

@@ -1,7 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.eventbus;
-
-class ArticleRetrievedEvent {
-    /**
-     * Message broker model implementation comes here
-     */
-}

src/main/java/tech/allegro/hexagon/articles/adapters/eventbus/MessageBrokerArticleEventPublisher.java

@@ -1,29 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.eventbus;
-
-import tech.allegro.hexagon.articles.domain.model.Article;
-import tech.allegro.hexagon.articles.domain.ports.ArticleEventPublisher;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
-
-@Component
-class MessageBrokerArticleEventPublisher implements ArticleEventPublisher {
-
-    private final Logger log = LoggerFactory.getLogger(MessageBrokerArticleEventPublisher.class);
-
-    @Override
-    public void publishArticleCreationEvent(final Article article) {
-        /**
-         * message broker integration implementation using {@link ArticleCreatedEvent} comes here
-         */
-        log.info("Article: \"{}\" creation event published on event bus", article.title().value());
-    }
-
-    @Override
-    public void publishArticleRetrievalEvent(final Article article) {
-        /**
-         * message broker integration implementation using {@link ArticleRetrievedEvent} comes here
-         */
-        log.info("Article: \"{}\" retrieval event published on event bus", article.title().value());
-    }
-}

src/main/java/tech/allegro/hexagon/articles/adapters/messagebroker/ArticleCreatedMessage.java

@@ -0,0 +1,25 @@
+package tech.allegro.hexagon.articles.adapters.messagebroker;
+
+import tech.allegro.hexagon.articles.domain.model.Article;
+
+import java.time.ZonedDateTime;
+
+class ArticleCreatedMessage {
+
+    private final Article article;
+    private final ZonedDateTime sentAt;
+
+    private ArticleCreatedMessage(final Article article, final ZonedDateTime sentAt) {
+        this.article = article;
+        this.sentAt = sentAt;
+    }
+
+    static ArticleCreatedMessage of(Article article) {
+        return new ArticleCreatedMessage(article, ZonedDateTime.now());
+    }
+
+    @Override
+    public String toString() {
+        return String.format("\"Article >>%s<< created\"", article.title().value());
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/messagebroker/ArticleRetrievedMessage.java

@@ -0,0 +1,26 @@
+package tech.allegro.hexagon.articles.adapters.messagebroker;
+
+import tech.allegro.hexagon.articles.domain.model.Article;
+
+import java.time.ZonedDateTime;
+
+class ArticleRetrievedMessage {
+
+    private final Article article;
+
+    private final ZonedDateTime sentAt;
+
+    private ArticleRetrievedMessage(final Article article, final ZonedDateTime sentAt) {
+        this.article = article;
+        this.sentAt = sentAt;
+    }
+
+    static ArticleRetrievedMessage of(Article article) {
+        return new ArticleRetrievedMessage(article, ZonedDateTime.now());
+    }
+
+    @Override
+    public String toString() {
+        return String.format("\"Article >>%s<< retrieved\"", article.title().value());
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/messagebroker/MessageBrokerArticleMessageSender.java

@@ -0,0 +1,25 @@
+package tech.allegro.hexagon.articles.adapters.messagebroker;
+
+import org.springframework.stereotype.Component;
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.ports.ArticleMessageSender;
+
+@Component
+class MessageBrokerArticleMessageSender implements ArticleMessageSender {
+
+    @Override
+    public void sendMessageForCreated(final Article article) {
+        /**
+         * message broker integration implementation comes here
+         */
+        ArticleCreatedMessage.of(article);
+    }
+
+    @Override
+    public void sendMessageForRetrieved(final Article article) {
+        /**
+         * message broker integration implementation comes here
+         */
+        ArticleRetrievedMessage.of(article);
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/ArticleAuthorMailNotifier.java

@@ -1,21 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.notifications;
-
-import tech.allegro.hexagon.articles.domain.model.Article;
-import tech.allegro.hexagon.articles.domain.ports.ArticleAuthorNotifier;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
-
-@Component
-class ArticleAuthorMailNotifier implements ArticleAuthorNotifier {
-
-    private final Logger log = LoggerFactory.getLogger(ArticleAuthorMailNotifier.class);
-
-    @Override
-    public void notifyAboutArticleCreation(final Article article) {
-        /**
-         * mail system integration implementation using {@link ArticleMailModel} comes here
-         */
-        log.info("Mail sent to author: \"{}\"", article.author().name());
-    }
-}

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/ArticleAuthorSmsNotifier.java

@@ -1,21 +0,0 @@
-package tech.allegro.hexagon.articles.adapters.notifications;
-
-import tech.allegro.hexagon.articles.domain.model.Article;
-import tech.allegro.hexagon.articles.domain.ports.ArticleAuthorNotifier;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
-
-@Component
-class ArticleAuthorSmsNotifier implements ArticleAuthorNotifier {
-
-    private final Logger log = LoggerFactory.getLogger(ArticleAuthorSmsNotifier.class);
-
-    @Override
-    public void notifyAboutArticleCreation(final Article article) {
-        /**
-         * sms system integration implementation using {@link ArticleSmsModel}comes here
-         */
-        log.info("SMS sent to author: \"{}\"", article.author().name());
-    }
-}

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/ArticleMailModel.java

@@ -1,7 +1,32 @@
 package tech.allegro.hexagon.articles.adapters.notifications;
 
+import tech.allegro.hexagon.articles.domain.model.Article;
+
 class ArticleMailModel {
-    /**
-     * Mail model implementation comes here
-     */
+
+    private static final String SUBJECT = "You have successfully published: >>%s<<";
+    private static final String CONTENT = "Check if everything is correct: >>%s<<";
+
+    private final String recipientId;
+    private final String subject;
+    private final String content;
+
+    private ArticleMailModel(final String recipientId,
+                             final String subject,
+                             final String content) {
+        this.recipientId = recipientId;
+        this.subject = subject;
+        this.content = content;
+    }
+
+    static ArticleMailModel of(final Article article) {
+        return new ArticleMailModel(article.author().name().value(),
+                String.format(SUBJECT, article.title().value()),
+                String.format(CONTENT, article.content().value()));
+    }
+
+    @Override
+    public String toString() {
+        return subject;
+    }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/ArticleSmsModel.java

@@ -1,7 +1,27 @@
 package tech.allegro.hexagon.articles.adapters.notifications;
 
+import tech.allegro.hexagon.articles.domain.model.Article;
+
 class ArticleSmsModel {
-    /**
-     * Sms model implementation comes here
-     */
+
+    public static final String CONTENT = "Please check your email. We have sent you publication details of the article: >>%s<<";
+    private final String recipientId;
+    private final String text;
+
+    private ArticleSmsModel(final String recipientId, final String text) {
+        this.recipientId = recipientId;
+        this.text = text;
+    }
+
+    public static ArticleSmsModel of(Article article) {
+        return new ArticleSmsModel(
+                article.author().name().value(),
+                String.format(CONTENT, article.title().value()));
+
+    }
+
+    @Override
+    public String toString() {
+        return text;
+    }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/AuthorMailNotifier.java

@@ -0,0 +1,17 @@
+package tech.allegro.hexagon.articles.adapters.notifications;
+
+import org.springframework.stereotype.Component;
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.ports.AuthorNotifier;
+
+@Component
+class AuthorMailNotifier implements AuthorNotifier {
+
+    @Override
+    public void notifyAboutCreationOf(final Article article) {
+        /**
+         * Mail system integration implementation comes here
+         */
+        ArticleMailModel.of(article);
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/notifications/AuthorSmsNotifier.java

@@ -0,0 +1,17 @@
+package tech.allegro.hexagon.articles.adapters.notifications;
+
+import org.springframework.stereotype.Component;
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.ports.AuthorNotifier;
+
+@Component
+class AuthorSmsNotifier implements AuthorNotifier {
+
+    @Override
+    public void notifyAboutCreationOf(final Article article) {
+        /**
+         * SMS system integration implementation comes here
+         */
+        ArticleSmsModel.of(article);
+    }
+}

src/main/java/tech/allegro/hexagon/articles/adapters/socialmedia/ArticleTwitterModel.java

@@ -1,7 +1,28 @@
 package tech.allegro.hexagon.articles.adapters.socialmedia;
 
+import tech.allegro.hexagon.articles.domain.model.Article;
+
 class ArticleTwitterModel {
-    /**
-     * twitter implementation comes here
-     */
+
+    public static final String TWEET = "Check out the new article >>%s<< by %s";
+    private final String twitterAccountId;
+    private final String tweet;
+
+    private ArticleTwitterModel(final String twitterAccountId, final String tweet) {
+        this.twitterAccountId = twitterAccountId;
+        this.tweet = tweet;
+    }
+
+    static ArticleTwitterModel of(Article article) {
+        final String title = article
+                .title()
+                .value();
+        final String twitterId = article.author().name().value();
+        return new ArticleTwitterModel(twitterId, String.format(TWEET, title, twitterId));
+    }
+
+    @Override
+    public String toString() {
+        return tweet;
+    }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/socialmedia/TwitterArticlePublisher.java

@@ -1,22 +1,21 @@
 package tech.allegro.hexagon.articles.adapters.socialmedia;
 
+import org.springframework.stereotype.Component;
 import tech.allegro.hexagon.articles.domain.model.Article;
 import tech.allegro.hexagon.articles.domain.ports.SocialMediaPublisher;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.springframework.stereotype.Component;
 
 @Component
 class TwitterArticlePublisher implements SocialMediaPublisher {
 
-    private final Logger log = LoggerFactory.getLogger(TwitterArticlePublisher.class);
+    private final TwitterClient twitterClient;
 
+    TwitterArticlePublisher(final TwitterClient twitterClient) {
+        this.twitterClient = twitterClient;
+    }
 
     @Override
     public void publish(final Article article) {
-        /**
-         * social media integration implementation  using {@link TwitterModel} comes here
-         */
-        log.info("Article: \"{}\" published on twitter", article.title().value());
+        final ArticleTwitterModel articleTweet = ArticleTwitterModel.of(article);
+        twitterClient.tweet(articleTweet);
     }
 }

src/main/java/tech/allegro/hexagon/articles/adapters/socialmedia/TwitterClient.java

@@ -0,0 +1,12 @@
+package tech.allegro.hexagon.articles.adapters.socialmedia;
+
+import org.springframework.stereotype.Component;
+
+@Component
+class TwitterClient {
+    void tweet(final ArticleTwitterModel articleTweet) {
+        /**
+         * social media integration implementation comes here
+         */
+    }
+}

src/main/java/tech/allegro/hexagon/articles/config/ArticleConfig.java

@@ -0,0 +1,38 @@
+package tech.allegro.hexagon.articles.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import tech.allegro.hexagon.articles.domain.ArticlePublisher;
+import tech.allegro.hexagon.articles.domain.ports.ArticleMessageSender;
+import tech.allegro.hexagon.articles.domain.ports.ArticleRepository;
+import tech.allegro.hexagon.articles.domain.ports.ArticleService;
+import tech.allegro.hexagon.articles.domain.ports.AuthorNotifier;
+import tech.allegro.hexagon.articles.domain.ports.AuthorRepository;
+import tech.allegro.hexagon.articles.domain.ports.SocialMediaPublisher;
+
+import java.util.List;
+
+@Configuration
+class ArticleConfig {
+
+    @Bean
+    ArticlePublisher articleEventPublisher(final ArticleMessageSender eventPublisher,
+                                           final List<SocialMediaPublisher> socialMediaPublishers,
+                                           final List<AuthorNotifier> articleAuthorNotifiers) {
+        return new ArticlePublisher(eventPublisher,
+                socialMediaPublishers,
+                articleAuthorNotifiers);
+    }
+
+    @Bean
+    ArticleService articleService(final ArticleRepository articleRepository,
+                                  final AuthorRepository authorRepository,
+                                  final ArticlePublisher articleEventPublisher
+    ) {
+        return new ArticleService(
+                articleRepository,
+                authorRepository,
+                articleEventPublisher);
+    }
+
+}

src/main/java/tech/allegro/hexagon/articles/domain/ArticleFacade.java

@@ -1,47 +0,0 @@
-package tech.allegro.hexagon.articles.domain;
-
-import tech.allegro.hexagon.articles.domain.model.Article;
-import tech.allegro.hexagon.articles.domain.model.ArticleId;
-import tech.allegro.hexagon.articles.domain.model.Author;
-import tech.allegro.hexagon.articles.domain.model.AuthorId;
-import tech.allegro.hexagon.articles.domain.model.Content;
-import tech.allegro.hexagon.articles.domain.model.Title;
-import tech.allegro.hexagon.articles.domain.ports.ArticleAuthorNotifier;
-import tech.allegro.hexagon.articles.domain.ports.ArticleEventPublisher;
-import tech.allegro.hexagon.articles.domain.ports.ArticleRepository;
-import tech.allegro.hexagon.articles.domain.ports.AuthorRepository;
-import tech.allegro.hexagon.articles.domain.ports.SocialMediaPublisher;
-
-import java.util.List;
-
-public class ArticleFacade {
-
-    private final ArticleEventPublisher eventPublisher;
-    private final ArticleRepository articleRepository;
-    private final AuthorRepository authorRepository;
-    private final List<SocialMediaPublisher> socialMediaPublishers;
-    private final List<ArticleAuthorNotifier> articleAuthorNotifiers;
-
-    public ArticleFacade(final ArticleEventPublisher eventPublisher, final ArticleRepository articleRepository, final AuthorRepository authorRepository, final List<SocialMediaPublisher> socialMediaPublishers, final List<ArticleAuthorNotifier> articleAuthorNotifiers) {
-        this.eventPublisher = eventPublisher;
-        this.articleRepository = articleRepository;
-        this.authorRepository = authorRepository;
-        this.socialMediaPublishers = socialMediaPublishers;
-        this.articleAuthorNotifiers = articleAuthorNotifiers;
-    }
-
-    public ArticleId create(final AuthorId authorId, final Title title, final Content content) {
-        final Author author = authorRepository.get(authorId);
-        final Article article = articleRepository.save(author, title, content);
-        eventPublisher.publishArticleCreationEvent(article);
-        socialMediaPublishers.forEach(socialMediaPublisher -> socialMediaPublisher.publish(article));
-        articleAuthorNotifiers.forEach(articleAuthorNotifier -> articleAuthorNotifier.notifyAboutArticleCreation(article));
-        return article.id();
-    }
-
-    public Article get(final ArticleId id) {
-        final Article article = articleRepository.get(id);
-        eventPublisher.publishArticleRetrievalEvent(article);
-        return article;
-    }
-}

src/main/java/tech/allegro/hexagon/articles/domain/ArticlePublisher.java

@@ -0,0 +1,32 @@
+package tech.allegro.hexagon.articles.domain;
+
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.ports.ArticleMessageSender;
+import tech.allegro.hexagon.articles.domain.ports.AuthorNotifier;
+import tech.allegro.hexagon.articles.domain.ports.SocialMediaPublisher;
+
+import java.util.List;
+
+public class ArticlePublisher {
+    private final ArticleMessageSender messageSender;
+    private final List<SocialMediaPublisher> socialMediaPublishers;
+    private final List<AuthorNotifier> articleAuthorNotifiers;
+
+    public ArticlePublisher(final ArticleMessageSender messageSender,
+                            final List<SocialMediaPublisher> socialMediaPublishers,
+                            final List<AuthorNotifier> articleAuthorNotifiers) {
+        this.messageSender = messageSender;
+        this.socialMediaPublishers = socialMediaPublishers;
+        this.articleAuthorNotifiers = articleAuthorNotifiers;
+    }
+
+    public void publishCreationOf(final Article article) {
+        messageSender.sendMessageForCreated(article);
+        socialMediaPublishers.forEach(socialMediaPublisher -> socialMediaPublisher.publish(article));
+        articleAuthorNotifiers.forEach(articleAuthorNotifier -> articleAuthorNotifier.notifyAboutCreationOf(article));
+    }
+
+    public void publishRetrievalOf(final Article article) {
+        messageSender.sendMessageForRetrieved(article);
+    }
+}

src/main/java/tech/allegro/hexagon/articles/domain/model/Article.java

@@ -1,12 +1,12 @@
 package tech.allegro.hexagon.articles.domain.model;
 
 public class Article {
+
     private final ArticleId id;
     private final Title title;
     private final Content content;
     private final Author author;
 
-
     private Article(final ArticleId id, final Title title, final Content content, final Author author) {
         this.id = id;
         this.title = title;
@@ -14,6 +14,16 @@ public class Article {
         this.author = author;
     }
 
+    public void validateEligibilityForPublication() {
+        verifyForPlagiarism();
+        validateTitleLength();
+        validateContentLength();
+        checkPunctuation();
+        checkGrammar();
+        checkStyle();
+        //TODO: these methods are just placeholders with empty implementation
+    }
+
     public ArticleId id() {
         return id;
     }
@@ -30,6 +40,24 @@ public class Article {
         return author;
     }
 
+    private void checkGrammar() {
+    }
+
+    private void checkStyle() {
+    }
+
+    private void checkPunctuation() {
+    }
+
+    private void verifyForPlagiarism() {
+    }
+
+    private void validateContentLength() {
+    }
+
+    private void validateTitleLength() {
+    }
+
     public static ArticleBuilder article() {
         return new ArticleBuilder();
     }

src/main/java/tech/allegro/hexagon/articles/domain/model/Author.java

@@ -5,7 +5,7 @@ public class Author {
     private final PersonName name;
 
 
-    public Author(final AuthorId id, final PersonName name) {
+    private Author(final AuthorId id, final PersonName name) {
         this.id = id;
         this.name = name;
     }
@@ -18,6 +18,10 @@ public class Author {
         return name;
     }
 
+    public AuthorId id() {
+        return id;
+    }
+
     public static final class AuthorBuilder {
         private AuthorId id;
         private PersonName name;

src/main/java/tech/allegro/hexagon/articles/domain/ports/ArticleEventPublisher.java

@@ -1,11 +0,0 @@
-package tech.allegro.hexagon.articles.domain.ports;
-
-import tech.allegro.hexagon.articles.domain.model.Article;
-
-public interface ArticleEventPublisher {
-
-    void publishArticleCreationEvent(Article article);
-
-    void publishArticleRetrievalEvent(Article article);
-
-}

src/main/java/tech/allegro/hexagon/articles/domain/ports/ArticleMessageSender.java

@@ -0,0 +1,11 @@
+package tech.allegro.hexagon.articles.domain.ports;
+
+import tech.allegro.hexagon.articles.domain.model.Article;
+
+public interface ArticleMessageSender {
+
+    void sendMessageForCreated(Article article);
+
+    void sendMessageForRetrieved(Article article);
+
+}

src/main/java/tech/allegro/hexagon/articles/domain/ports/ArticleService.java

@@ -0,0 +1,41 @@
+package tech.allegro.hexagon.articles.domain.ports;
+
+import tech.allegro.hexagon.articles.domain.ArticlePublisher;
+import tech.allegro.hexagon.articles.domain.model.Article;
+import tech.allegro.hexagon.articles.domain.model.ArticleId;
+import tech.allegro.hexagon.articles.domain.model.Author;
+import tech.allegro.hexagon.articles.domain.model.AuthorId;
+import tech.allegro.hexagon.articles.domain.model.Content;
+import tech.allegro.hexagon.articles.domain.model.Title;
+
+public final class ArticleService {
+
+    private final ArticleRepository articleRepository;
+    private final AuthorRepository authorRepository;
+    private final ArticlePublisher eventPublisher;
+
+
+    public ArticleService(final ArticleRepository articleRepository,
+                          final AuthorRepository authorRepository,
+                          final ArticlePublisher eventPublisher) {
+        this.articleRepository = articleRepository;
+        this.authorRepository = authorRepository;
+        this.eventPublisher = eventPublisher;
+    }
+
+    public ArticleId create(final AuthorId authorId, final Title title, final Content content) {
+        final Author author = authorRepository.get(authorId);
+        final Article article = articleRepository.save(author, title, content);
+
+        article.validateEligibilityForPublication();
+
+        eventPublisher.publishCreationOf(article);
+        return article.id();
+    }
+
+    public Article get(final ArticleId id) {
+        final Article article = articleRepository.get(id);
+        eventPublisher.publishRetrievalOf(article);
+        return article;
+    }
+}

src/main/java/tech/allegro/hexagon/articles/domain/ports/AuthorNotifier.java

@@ -2,8 +2,8 @@ package tech.allegro.hexagon.articles.domain.ports;
 
 import tech.allegro.hexagon.articles.domain.model.Article;
 
-public interface ArticleAuthorNotifier {
+public interface AuthorNotifier {
 
-    void notifyAboutArticleCreation(Article article);
+    void notifyAboutCreationOf(Article article);
 
 }