updated

Author: Chaklader Asfak Arefe

.DS_Store

@@ -6,12 +6,14 @@
 import com.iluwatar.cqrs.domain.model.Book;
 import com.iluwatar.cqrs.util.HibernateUtil;
 
+
 /**
  * This class is an implementation of {@link ICommandService} interface. It uses Hibernate as an api for persistence.
  *
  */
 public class CommandServiceImpl implements ICommandService {
 
+
     private SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
 
     private Author getAuthorByUsername(String username) {
@@ -33,38 +35,45 @@ private Author getAuthorByUsername(String username) {
     }
 
     private Book getBookByTitle(String title) {
-      Book book = null;
-      try (Session session = sessionFactory.openSession()) {
-        Query query = session.createQuery("from Book where title=:title");
-        query.setParameter("title", title);
-        book = (Book) query.uniqueResult();
-      }
-      if (book == null) {
-        HibernateUtil.getSessionFactory().close();
-        throw new NullPointerException("Book " + title + " doesn't exist!");
-      }
-      return book;
+
+        Book book = null;
+
+        try (Session session = sessionFactory.openSession()) {
+          Query query = session.createQuery("from Book where title=:title");
+          query.setParameter("title", title);
+          book = (Book) query.uniqueResult();
+        }
+
+        if (book == null) {
+          HibernateUtil.getSessionFactory().close();
+          throw new NullPointerException("Book " + title + " doesn't exist!");
+        }
+        return book;
     }
 
+
     @Override
     public void authorCreated(String username, String name, String email) {
-      Author author = new Author(username, name, email);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.save(author);
-        session.getTransaction().commit();
-      }
+        Author author = new Author(username, name, email);
+  
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.save(author);
+          session.getTransaction().commit();
+        }
     }
 
     @Override
     public void bookAddedToAuthor(String title, double price, String username) {
-      Author author = getAuthorByUsername(username);
-      Book book = new Book(title, price, author);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.save(book);
-        session.getTransaction().commit();
-      }
+    
+        Author author = getAuthorByUsername(username);
+        Book book = new Book(title, price, author);
+    
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.save(book);
+          session.getTransaction().commit();
+        }
     }
 
     @Override
@@ -80,46 +89,53 @@ public void authorNameUpdated(String username, String name) {
 
     @Override
     public void authorUsernameUpdated(String oldUsername, String newUsername) {
-      Author author = getAuthorByUsername(oldUsername);
-      author.setUsername(newUsername);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.update(author);
-        session.getTransaction().commit();
-      }
+  
+        Author author = getAuthorByUsername(oldUsername);
+        author.setUsername(newUsername);
+  
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.update(author);
+          session.getTransaction().commit();
+        }
     }
 
     @Override
     public void authorEmailUpdated(String username, String email) {
-      Author author = getAuthorByUsername(username);
-      author.setEmail(email);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.update(author);
-        session.getTransaction().commit();
-      }
+  
+        Author author = getAuthorByUsername(username);
+        author.setEmail(email);
+  
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.update(author);
+          session.getTransaction().commit();
+        }
     }
 
     @Override
     public void bookTitleUpdated(String oldTitle, String newTitle) {
-      Book book = getBookByTitle(oldTitle);
-      book.setTitle(newTitle);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.update(book);
-        session.getTransaction().commit();
-      }
+  
+        Book book = getBookByTitle(oldTitle);
+        book.setTitle(newTitle);
+  
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.update(book);
+          session.getTransaction().commit();
+        }
     }
 
     @Override
     public void bookPriceUpdated(String title, double price) {
-      Book book = getBookByTitle(title);
-      book.setPrice(price);
-      try (Session session = sessionFactory.openSession()) {
-        session.beginTransaction();
-        session.update(book);
-        session.getTransaction().commit();
-      }
+        Book book = getBookByTitle(title);
+        book.setPrice(price);
+     
+        try (Session session = sessionFactory.openSession()) {
+          session.beginTransaction();
+          session.update(book);
+          session.getTransaction().commit();
+        }
     }
 
 }

Design_Patterns/.DS_Store

@@ -5,18 +5,17 @@
  */
 public interface ICommandService {
 
-  void authorCreated(String username, String name, String email);
+	void authorCreated(String username, String name, String email);
 
-  void bookAddedToAuthor(String title, double price, String username);
+	void bookAddedToAuthor(String title, double price, String username);
 
-  void authorNameUpdated(String username, String name);
+	void authorNameUpdated(String username, String name);
 
-  void authorUsernameUpdated(String oldUsername, String newUsername);
+	void authorUsernameUpdated(String oldUsername, String newUsername);
 
-  void authorEmailUpdated(String username, String email);
+	void authorEmailUpdated(String username, String email);
 
-  void bookTitleUpdated(String oldTitle, String newTitle);
-
-  void bookPriceUpdated(String title, double price);
+	void bookTitleUpdated(String oldTitle, String newTitle);
 
+	void bookPriceUpdated(String title, double price);
 }

Design_Patterns/CQRS/Library/commandes/CommandServiceImpl.java

@@ -9,8 +9,12 @@ Use the Caching pattern(s) when
 
 * Repetitious acquisition, initialization, and release of the same resource causes unnecessary performance overhead.
 
+
 ## Credits
+## -------
+
+[Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained)
+
+[Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177)
 
-* [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained)
-* [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177)
-* [Cache-Aside](https://msdn.microsoft.com/en-us/library/dn589799.aspx)
+[Cache-Aside](https://msdn.microsoft.com/en-us/library/dn589799.aspx)

Design_Patterns/CQRS/Library/commandes/ICommandService.java

@@ -55,12 +55,15 @@ public class App {
      * @param args command line args
      */
     public static void main(String[] args) {
+
         AppManager.initDb(false); // VirtualDB (instead of MongoDB) was used in running the JUnit tests
                                   // and the App class to avoid Maven compilation errors. Set flag to
                                   // true to run the tests with MongoDB (provided that MongoDB is
                                   // installed and socket connection is open).
+
         AppManager.initCacheCapacity(3);
         App app = new App();
+
         app.useReadAndWriteThroughStrategy();
         app.useReadThroughAndWriteAroundStrategy();
         app.useReadThroughAndWriteBehindStrategy();
@@ -69,39 +72,39 @@ public static void main(String[] args) {
 
     /**
      * Read-through and write-through
-     */
+     */  
     public void useReadAndWriteThroughStrategy() {
-      LOGGER.info("# CachingPolicy.THROUGH");
-      AppManager.initCachingPolicy(CachingPolicy.THROUGH);
+        LOGGER.info("# CachingPolicy.THROUGH");
+        AppManager.initCachingPolicy(CachingPolicy.THROUGH);
 
-      UserAccount userAccount1 = new UserAccount("001", "John", "He is a boy.");
+        UserAccount userAccount1 = new UserAccount("001", "John", "He is a boy.");
 
-      AppManager.save(userAccount1);
-      LOGGER.info(AppManager.printCacheContent());
-      AppManager.find("001");
-      AppManager.find("001");
+        AppManager.save(userAccount1);
+        LOGGER.info(AppManager.printCacheContent());
+        AppManager.find("001");
+        AppManager.find("001");
     }
 
     /**
      * Read-through and write-around
      */
     public void useReadThroughAndWriteAroundStrategy() {
-      LOGGER.info("# CachingPolicy.AROUND");
-      AppManager.initCachingPolicy(CachingPolicy.AROUND);
-
-      UserAccount userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
-
-      AppManager.save(userAccount2);
-      LOGGER.info(AppManager.printCacheContent());
-      AppManager.find("002");
-      LOGGER.info(AppManager.printCacheContent());
-      userAccount2 = AppManager.find("002");
-      userAccount2.setUserName("Jane G.");
-      AppManager.save(userAccount2);
-      LOGGER.info(AppManager.printCacheContent());
-      AppManager.find("002");
-      LOGGER.info(AppManager.printCacheContent());
-      AppManager.find("002");
+        LOGGER.info("# CachingPolicy.AROUND");
+        AppManager.initCachingPolicy(CachingPolicy.AROUND);
+
+        UserAccount userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
+
+        AppManager.save(userAccount2);
+        LOGGER.info(AppManager.printCacheContent());
+        AppManager.find("002");
+        LOGGER.info(AppManager.printCacheContent());
+        userAccount2 = AppManager.find("002");
+        userAccount2.setUserName("Jane G.");
+        AppManager.save(userAccount2);
+        LOGGER.info(AppManager.printCacheContent());
+        AppManager.find("002");
+        LOGGER.info(AppManager.printCacheContent());
+        AppManager.find("002");
     }
 
     /**

Design_Patterns/CQRS/Library/domain/.DS_Store

@@ -22,37 +22,40 @@ private CacheStore() {
    * Init cache capacity
    */
   public static void initCapacity(int capacity) {
-    if (cache == null) {
-      cache = new LruCache(capacity);
-    } else {
-      cache.setCapacity(capacity);
-    }
+      if (cache == null) {
+        cache = new LruCache(capacity);
+      } else {
+        cache.setCapacity(capacity);
+      }
   }
 
   /**
    * Get user account using read-through cache
    */
   public static UserAccount readThrough(String userId) {
-    if (cache.contains(userId)) {
-      LOGGER.info("# Cache Hit!");
-      return cache.get(userId);
-    }
-    LOGGER.info("# Cache Miss!");
-    UserAccount userAccount = DbManager.readFromDb(userId);
-    cache.set(userId, userAccount);
-    return userAccount;
+
+      if (cache.contains(userId)) {
+        LOGGER.info("# Cache Hit!");
+        return cache.get(userId);
+      }
+
+      LOGGER.info("# Cache Miss!");
+      UserAccount userAccount = DbManager.readFromDb(userId);
+
+      cache.set(userId, userAccount);
+      return userAccount;
   }
 
   /**
    * Get user account using write-through cache
    */
   public static void writeThrough(UserAccount userAccount) {
-    if (cache.contains(userAccount.getUserId())) {
-      DbManager.updateDb(userAccount);
-    } else {
-      DbManager.writeToDb(userAccount);
-    }
-    cache.set(userAccount.getUserId(), userAccount);
+      if (cache.contains(userAccount.getUserId())) {
+        DbManager.updateDb(userAccount);
+      } else {
+        DbManager.writeToDb(userAccount);
+      }
+      cache.set(userAccount.getUserId(), userAccount);
   }
 
   /**
@@ -72,19 +75,20 @@ public static void writeAround(UserAccount userAccount) {
    * Get user account using read-through cache with write-back policy
    */
   public static UserAccount readThroughWithWriteBackPolicy(String userId) {
-    if (cache.contains(userId)) {
-      LOGGER.info("# Cache Hit!");
-      return cache.get(userId);
-    }
-    LOGGER.info("# Cache Miss!");
-    UserAccount userAccount = DbManager.readFromDb(userId);
-    if (cache.isFull()) {
-      LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
-      UserAccount toBeWrittenToDb = cache.getLruData();
-      DbManager.upsertDb(toBeWrittenToDb);
-    }
-    cache.set(userId, userAccount);
-    return userAccount;
+      if (cache.contains(userId)) {
+        LOGGER.info("# Cache Hit!");
+        return cache.get(userId);
+      }
+      
+      LOGGER.info("# Cache Miss!");
+      UserAccount userAccount = DbManager.readFromDb(userId);
+      if (cache.isFull()) {
+        LOGGER.info("# Cache is FULL! Writing LRU data to DB...");
+        UserAccount toBeWrittenToDb = cache.getLruData();
+        DbManager.upsertDb(toBeWrittenToDb);
+      }
+      cache.set(userId, userAccount);
+      return userAccount;
   }
 
   /**