docs: #590 refactor and add explanation for business delegate (#1686)

Type: docs and refactoring

Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>

business-delegate/src/main/java/com/iluwatar/business/delegate/App.java

@@ -33,9 +33,9 @@ package com.iluwatar.business.delegate;
  * retrieved through service lookups. The Business Delegate itself may contain business logic too
  * potentially tying together multiple service calls, exception handling, retrying etc.
  *
- * <p>In this example the client ({@link Client}) utilizes a business delegate (
- * {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
- * service and makes the service call.
+ * <p>In this example the client ({@link MobileClient}) utilizes a business delegate (
+ * {@link BusinessDelegate}) to search for movies in video streaming services. The Business Delegate
+ * then selects the appropriate service and makes the service call.
  */
 public class App {
 
@@ -46,18 +46,16 @@ public class App {
    */
   public static void main(String[] args) {
 
+    // prepare the objects
     var businessDelegate = new BusinessDelegate();
     var businessLookup = new BusinessLookup();
-    businessLookup.setEjbService(new EjbService());
-    businessLookup.setJmsService(new JmsService());
-
+    businessLookup.setNetflixService(new NetflixService());
+    businessLookup.setYouTubeService(new YouTubeService());
     businessDelegate.setLookupService(businessLookup);
-    businessDelegate.setServiceType(ServiceType.EJB);
 
-    var client = new Client(businessDelegate);
-    client.doTask();
-
-    businessDelegate.setServiceType(ServiceType.JMS);
-    client.doTask();
+    // create the client and use the business delegate
+    var client = new MobileClient(businessDelegate);
+    client.playbackMovie("Die Hard 2");
+    client.playbackMovie("Maradona: The Greatest Ever");
   }
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/BusinessDelegate.java

@@ -23,24 +23,18 @@
 
 package com.iluwatar.business.delegate;
 
+import lombok.Setter;
+
 /**
  * BusinessDelegate separates the presentation and business tiers.
  */
+@Setter
 public class BusinessDelegate {
 
   private BusinessLookup lookupService;
-  private ServiceType serviceType;
 
-  public void setLookupService(BusinessLookup businessLookup) {
-    this.lookupService = businessLookup;
-  }
-
-  public void setServiceType(ServiceType serviceType) {
-    this.serviceType = serviceType;
-  }
-
-  public void doTask() {
-    BusinessService businessService = lookupService.getBusinessService(serviceType);
-    businessService.doProcessing();
+  public void playbackMovie(String movie) {
+    VideoStreamingService videoStreamingService = lookupService.getBusinessService(movie);
+    videoStreamingService.doProcessing();
   }
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/BusinessLookup.java

@@ -23,6 +23,7 @@
 
 package com.iluwatar.business.delegate;
 
+import java.util.Locale;
 import lombok.Setter;
 
 /**
@@ -31,21 +32,21 @@ import lombok.Setter;
 @Setter
 public class BusinessLookup {
 
-  private EjbService ejbService;
+  private NetflixService netflixService;
 
-  private JmsService jmsService;
+  private YouTubeService youTubeService;
 
   /**
-   * Gets service instance based on service type.
+   * Gets service instance based on given movie search string.
    *
-   * @param serviceType Type of service instance to be returned.
+   * @param movie Search string for the movie.
    * @return Service instance.
    */
-  public BusinessService getBusinessService(ServiceType serviceType) {
-    if (serviceType.equals(ServiceType.EJB)) {
-      return ejbService;
+  public VideoStreamingService getBusinessService(String movie) {
+    if (movie.toLowerCase(Locale.ROOT).contains("die hard")) {
+      return netflixService;
     } else {
-      return jmsService;
+      return youTubeService;
     }
   }
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/MobileClient.java

@@ -24,17 +24,17 @@
 package com.iluwatar.business.delegate;
 
 /**
- * Client utilizes BusinessDelegate to call the business tier.
+ * MobileClient utilizes BusinessDelegate to call the business tier.
  */
-public class Client {
+public class MobileClient {
 
   private final BusinessDelegate businessDelegate;
 
-  public Client(BusinessDelegate businessDelegate) {
+  public MobileClient(BusinessDelegate businessDelegate) {
     this.businessDelegate = businessDelegate;
   }
 
-  public void doTask() {
-    businessDelegate.doTask();
+  public void playbackMovie(String movie) {
+    businessDelegate.playbackMovie(movie);
   }
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/NetflixService.java

@@ -26,13 +26,13 @@ package com.iluwatar.business.delegate;
 import lombok.extern.slf4j.Slf4j;
 
 /**
- * Service EJB implementation.
+ * NetflixService implementation.
  */
 @Slf4j
-public class EjbService implements BusinessService {
+public class NetflixService implements VideoStreamingService {
 
   @Override
   public void doProcessing() {
-    LOGGER.info("EjbService is now processing");
+    LOGGER.info("NetflixService is now processing");
   }
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/ServiceType.java

@@ -1,33 +0,0 @@
-/*
- * The MIT License
- * Copyright © 2014-2021 Ilkka Seppälä
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-package com.iluwatar.business.delegate;
-
-/**
- * Enumeration for service types.
- */
-public enum ServiceType {
-
-  EJB,
-  JMS
-}

business-delegate/src/main/java/com/iluwatar/business/delegate/VideoStreamingService.java

@@ -24,9 +24,9 @@
 package com.iluwatar.business.delegate;
 
 /**
- * Interface for service implementations.
+ * Interface for video streaming service implementations.
  */
-public interface BusinessService {
+public interface VideoStreamingService {
 
   void doProcessing();
 }

business-delegate/src/main/java/com/iluwatar/business/delegate/YouTubeService.java

@@ -26,13 +26,13 @@ package com.iluwatar.business.delegate;
 import lombok.extern.slf4j.Slf4j;
 
 /**
- * Service JMS implementation.
+ * YouTubeService implementation.
  */
 @Slf4j
-public class JmsService implements BusinessService {
+public class YouTubeService implements VideoStreamingService {
 
   @Override
   public void doProcessing() {
-    LOGGER.info("JmsService is now processing");
+    LOGGER.info("YouTubeService is now processing");
   }
 }