#84 Documented the Layers example

layers/src/main/java/com/iluwatar/layers/App.java

@@ -2,10 +2,67 @@ package com.iluwatar.layers;
 
 import java.util.Arrays;
 
+/**
+ * 
+ * <p>
+ * Multilayered architecture is an architectural style where software responsibilities are
+ * divided among the different layers of the application.
+ * </p>
+ * 
+ * <p>
+ * This example demonstrates a traditional 3-layer architecture consisting of data access
+ * layer, business layer and presentation layer.
+ * </p>
+ * 
+ * <p>
+ * The data access layer is formed of Spring Data repositories <code>CakeDao</code>, <code>CakeToppingDao</code> and
+ * <code>CakeLayerDao</code>. The repositories can be used for CRUD operations on cakes, cake toppings
+ * and cake layers respectively.
+ * </p>
+ * 
+ * <p>
+ * The business layer is built on top of the data access layer. <code>CakeBakingService</code> offers
+ * methods to retrieve available cake toppings and cake layers and baked cakes. Also the
+ * service is used to create new cakes out of cake toppings and cake layers.
+ * </p>
+ * 
+ * <p>
+ * The presentation layer is built on the business layer and in this example it simply lists
+ * the cakes that have been baked.
+ * </p>
+ * 
+ * <p>
+ * We have applied so called strict layering which means that the layers can only access 
+ * the classes directly beneath them. This leads the solution to create an additional set of
+ * DTOs (<code>CakeInfo</code>, <code>CakeToppingInfo</code>, <code>CakeLayerInfo</code>) 
+ * to translate data between layers. In other words, <code>CakeBakingService</code> cannot 
+ * return entities (<code>Cake</code>, <code>CakeTopping</code>, <code>CakeLayer</code>) 
+ * directly since these reside on data access layer but instead translates these into business 
+ * layer DTOs (<code>CakeInfo</code>, <code>CakeToppingInfo</code>, <code>CakeLayerInfo</code>) 
+ * and returns them instead. This way the presentation layer does not have any knowledge of 
+ * other layers than the business layer and thus is not affected by changes to them.
+ * </p>
+ *
+ * @see Cake
+ * @see CakeTopping
+ * @see CakeLayer
+ * @see CakeDao
+ * @see CakeToppingDao
+ * @see CakeLayerDao
+ * @see CakeBakingService
+ * @see CakeInfo
+ * @see CakeToppingInfo
+ * @see CakeLayerInfo
+ *
+ */
 public class App {
 
 	private static CakeBakingService cakeBakingService = new CakeBakingServiceImpl();
 	
+	/**
+	 * Application entry point
+	 * @param args Command line parameters
+	 */
 	public static void main(String[] args) {
 		
 		// initialize example data
@@ -16,6 +73,10 @@ public class App {
 		cakeView.render();
 	}
 	
+	/**
+	 * Initializes the example data
+	 * @param cakeBakingService
+	 */
 	private static void initializeData(CakeBakingService cakeBakingService) {
 		cakeBakingService.saveNewLayer(new CakeLayerInfo("chocolate", 1200));
 		cakeBakingService.saveNewLayer(new CakeLayerInfo("banana", 900));

layers/src/main/java/com/iluwatar/layers/Cake.java

@@ -11,6 +11,11 @@ import javax.persistence.Id;
 import javax.persistence.OneToMany;
 import javax.persistence.OneToOne;
 
+/**
+ * 
+ * Cake entity
+ *
+ */
 @Entity
 public class Cake {
 

layers/src/main/java/com/iluwatar/layers/CakeBakingException.java

@@ -1,7 +1,14 @@
 package com.iluwatar.layers;
 
+/**
+ * 
+ * Custom exception used in cake baking
+ *
+ */
 public class CakeBakingException extends Exception {
 	
+	private static final long serialVersionUID = 1L;
+
 	public CakeBakingException() {
 	}
 

layers/src/main/java/com/iluwatar/layers/CakeBakingService.java

@@ -2,17 +2,47 @@ package com.iluwatar.layers;
 
 import java.util.List;
 
+/**
+ * 
+ * Service for cake baking operations
+ *
+ */
 public interface CakeBakingService {
 	
+	/**
+	 * Bakes new cake according to parameters
+	 * @param cakeInfo
+	 * @throws CakeBakingException
+	 */
 	void bakeNewCake(CakeInfo cakeInfo) throws CakeBakingException;
 	
+	/**
+	 * Get all cakes
+	 * @return
+	 */
 	List<CakeInfo> getAllCakes();
 
+	/**
+	 * Store new cake topping
+	 * @param toppingInfo
+	 */
 	void saveNewTopping(CakeToppingInfo toppingInfo);
 
+	/**
+	 * Get available cake toppings
+	 * @return
+	 */
 	List<CakeToppingInfo> getAvailableToppings();
 	
+	/**
+	 * Add new cake layer
+	 * @param layerInfo
+	 */
 	void saveNewLayer(CakeLayerInfo layerInfo);
 	
+	/**
+	 * Get available cake layers
+	 * @return
+	 */
 	List<CakeLayerInfo> getAvailableLayers();
 }

layers/src/main/java/com/iluwatar/layers/CakeBakingServiceImpl.java

@@ -13,6 +13,11 @@ import org.springframework.context.support.ClassPathXmlApplicationContext;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+/**
+ * 
+ * Implementation of CakeBakingService
+ *
+ */
 @Service
 @Transactional
 public class CakeBakingServiceImpl implements CakeBakingService {

layers/src/main/java/com/iluwatar/layers/CakeDao.java

@@ -3,6 +3,11 @@ package com.iluwatar.layers;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
+/**
+ * 
+ * CRUD repository for cakes
+ *
+ */
 @Repository
 public interface CakeDao extends CrudRepository<Cake, Long> {
 

layers/src/main/java/com/iluwatar/layers/CakeInfo.java

@@ -3,6 +3,11 @@ package com.iluwatar.layers;
 import java.util.List;
 import java.util.Optional;
 
+/**
+ * 
+ * DTO for cakes
+ *
+ */
 public class CakeInfo {
 
 	public final Optional<Long> id;

layers/src/main/java/com/iluwatar/layers/CakeLayer.java

@@ -6,6 +6,11 @@ import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
 import javax.persistence.ManyToOne;
 
+/**
+ * 
+ * CakeLayer entity
+ *
+ */
 @Entity
 public class CakeLayer {
 

layers/src/main/java/com/iluwatar/layers/CakeLayerDao.java

@@ -3,6 +3,11 @@ package com.iluwatar.layers;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
+/**
+ * 
+ * CRUD repository for cake layers
+ *
+ */
 @Repository
 public interface CakeLayerDao extends CrudRepository<CakeLayer, Long> {
 

layers/src/main/java/com/iluwatar/layers/CakeLayerInfo.java

@@ -2,6 +2,11 @@ package com.iluwatar.layers;
 
 import java.util.Optional;
 
+/**
+ * 
+ * DTO for cake layers
+ *
+ */
 public class CakeLayerInfo {
 
 	public final Optional<Long> id;

layers/src/main/java/com/iluwatar/layers/CakeTopping.java

@@ -6,6 +6,11 @@ import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
 import javax.persistence.OneToOne;
 
+/**
+ * 
+ * CakeTopping entity
+ *
+ */
 @Entity
 public class CakeTopping {
 

layers/src/main/java/com/iluwatar/layers/CakeToppingDao.java

@@ -3,6 +3,11 @@ package com.iluwatar.layers;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
+/**
+ * 
+ * CRUD repository cake toppings
+ *
+ */
 @Repository
 public interface CakeToppingDao extends CrudRepository<CakeTopping, Long> {
 

layers/src/main/java/com/iluwatar/layers/CakeToppingInfo.java

@@ -2,6 +2,11 @@ package com.iluwatar.layers;
 
 import java.util.Optional;
 
+/**
+ * 
+ * DTO for cake toppings
+ *
+ */
 public class CakeToppingInfo {
 
 	public final Optional<Long> id;

layers/src/main/java/com/iluwatar/layers/CakeViewImpl.java

@@ -1,5 +1,10 @@
 package com.iluwatar.layers;
 
+/**
+ * 
+ * View implementation for displaying cakes
+ *
+ */
 public class CakeViewImpl implements View {
 
 	private CakeBakingService cakeBakingService;

layers/src/main/java/com/iluwatar/layers/View.java

@@ -1,5 +1,10 @@
 package com.iluwatar.layers;
 
+/**
+ * 
+ * View interface
+ *
+ */
 public interface View {
 
 	void render();