Issue #450. First commit. Queue Based Load Leveling

queue-load-leveling/src/main/java/org/queue/load/leveling/App.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ * Many solutions in the cloud involve running tasks that invoke services. In this environment, 
+ * if a service is subjected to intermittent heavy loads, it can cause performance or reliability issues.
+ * <p>
+ * A service could be a component that is part of the same solution as the tasks that utilize it, or it 
+ * could be a third-party service providing access to frequently used resources such as a cache or a storage service.
+ * If the same service is utilized by a number of tasks running concurrently, it can be difficult to predict the 
+ * volume of requests to which the service might be subjected at any given point in time.
+ * <p>
+ * We will build a queue-based-load-leveling to solve above problem. 
+ * Refactor the solution and introduce a queue between the task and the service. 
+ * The task and the service run asynchronously. The task posts a message containing the data required 
+ * by the service to a queue. The queue acts as a buffer, storing the message until it is retrieved 
+ * by the service. The service retrieves the messages from the queue and processes them. 
+ * Requests from a number of tasks, which can be generated at a highly variable rate, can be passed 
+ * to the service through the same message queue.
+ * <p>
+ * The queue effectively decouples the tasks from the service, and the service can handle the messages 
+ * at its own pace irrespective of the volume of requests from concurrent tasks. Additionally, 
+ * there is no delay to a task if the service is not available at the time it posts a message to the queue.
+ * <p>
+ * In this example we have a class {@link MessageQueue} to hold the message {@link Message} objects. 
+ * All the worker threads {@link TaskGenerator} will submit the messages to the MessageQueue. 
+ * The service executor class {@link ServiceExecutor} will pick up one task at a time from the Queue and 
+ * execute them.
+ *  
+ */
+public class App {
+  
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  
+  /**
+   * Program entry point
+   * 
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    try {
+      // Create a MessageQueue object.
+      MessageQueue msgQueue = new MessageQueue();
+        
+      LOGGER.info("All the TaskGenerators started.");
+      
+      // Create three TaskGenerator threads. Each of them will submit different number of jobs.
+      Runnable taskRunnable_1 = new TaskGenerator(msgQueue, 5);
+      Runnable taskRunnable_2 = new TaskGenerator(msgQueue, 1);
+      Runnable taskRunnable_3 = new TaskGenerator(msgQueue, 2);
+      
+      Thread taskGenerator_1 = new Thread(taskRunnable_1, "Task_Generator_1");
+      Thread taskGenerator_2 = new Thread(taskRunnable_2, "Task_Generator_2");
+      Thread taskGenerator_3 = new Thread(taskRunnable_3, "Task_Generator_3");
+      
+      taskGenerator_1.start();
+      taskGenerator_2.start();
+      taskGenerator_3.start();
+      
+      LOGGER.info("Service Executor started.");
+      
+      // First create e service which will process all the jobs.
+      Runnable srvRunnable = new ServiceExecutor(msgQueue);
+      Thread srvExec = new Thread(srvRunnable, "Service_Executor_Thread");
+      srvExec.start();
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+  }
+}

queue-load-leveling/src/main/java/org/queue/load/leveling/Message.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+/**
+ *  Message class with only one parameter.
+ *
+*/
+public class Message {
+  private String msg;
+
+  // Empty constructor.
+  public Message() {
+  }
+  
+  // Parameter constructor.
+  public Message(String msg) {
+    super();
+    this.msg = msg;
+  }
+
+  // Get Method for attribute msg.
+  public String getMsg() {
+    return msg;
+  }
+  
+  // Set Method for attribute msg.
+  public void setMsg(String msg) {
+    this.msg = msg;
+  }
+  
+  @Override
+  public String toString() {
+    return msg;
+  }
+}

queue-load-leveling/src/main/java/org/queue/load/leveling/MessageQueue.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ * MessageQueue class.
+ * In this class we will create a Blocking Queue and 
+ * submit/retrieve all the messages from it.
+ */
+public class MessageQueue {
+  
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  
+  private BlockingQueue<Message> blkQueue;
+  
+  // Default constructor when called creates Blocking Queue object. 
+  public MessageQueue() {
+    this.blkQueue = new ArrayBlockingQueue<Message>(1024);
+  }
+  
+  /**
+   * All the TaskGenerator threads will call this method to insert the
+   * Messages in to the Blocking Queue. 
+   * @param msg
+   */
+  public void submitMsg(Message msg) {
+    try {
+      if(null != msg) {
+        blkQueue.add(msg);
+      }
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+  }
+  
+  /**
+   * All the messages will be retrieved by the ServiceExecutor by 
+   * calling this method and process them.
+   * Retrieves and removes the head of this queue, or returns null if this queue is empty.
+   */
+  public Message retrieveMsg() {
+    Message retrievedMsg = null;
+    try {
+       retrievedMsg = blkQueue.poll();
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+    
+    return retrievedMsg;
+  }
+}

queue-load-leveling/src/main/java/org/queue/load/leveling/ServiceExecutor.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ *  ServiceExecuotr class.
+ *  This class will pick up Messages one by one from 
+ *  the Blocking Queue and process them.
+ */
+public class ServiceExecutor implements Runnable {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  
+  private MessageQueue msgQueue;
+
+  public ServiceExecutor(MessageQueue msgQueue) {
+    this.msgQueue = msgQueue;
+  }
+  
+  /**
+   * The ServiceExecutor thread will retrieve each message and process it.
+   */
+  public void run() {
+    try {
+      while(true) {
+        Message msg = msgQueue.retrieveMsg();
+        
+        if(null != msg) {
+          LOGGER.info(msg.toString() + " is served.");
+        } else {
+          LOGGER.info("ServiceExecutor: All tasks are executed. Waiting.");
+        }
+        
+        Thread.sleep(1000);
+      }
+    } catch(InterruptedException ie) { 
+      LOGGER.error(ie.getMessage());
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+  }
+}

queue-load-leveling/src/main/java/org/queue/load/leveling/Task.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+/**
+ * Task Interface.
+ * 
+*/
+public interface Task {
+  public void submit(Message msg);
+}

queue-load-leveling/src/main/java/org/queue/load/leveling/TaskGenerator.java

@@ -0,0 +1,87 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * TaskGenerator class.
+ * Each TaskGenerator thread will be a Worker which submit's messages to the queue.
+ * We need to mention the message count for each of the TaskGenerator threads.
+ * 
+*/
+public class TaskGenerator implements Task, Runnable {
+
+  
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  
+  // MessageQueue reference using which we will submit our messages.
+  private MessageQueue msgQueue;
+  
+  // Total message count that a TaskGenerator will submit.
+  private int msgCount;
+  
+  // Parameterized constructor.
+  public TaskGenerator(MessageQueue msgQueue, int msgCount) {
+    this.msgQueue = msgQueue;
+    this.msgCount = msgCount;
+  }
+  
+  /**
+   * Submit messages to the Blocking Queue.
+   */
+  public void submit(Message msg) {
+    try {
+      this.msgQueue.submitMsg(msg);
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+  }
+  
+  /**
+   * Each TaskGenerator thread will submit all the messages to the Queue.
+   * After every message submission TaskGenerator thread will sleep for 1 second.
+   */
+  public void run() {
+    try {
+      while(this.msgCount > 0) {
+        String statusMsg = "Message-" + this.msgCount + " submitted by " + Thread.currentThread().getName();
+        Message newMessage = new Message(statusMsg);
+        this.submit(newMessage);
+        
+        LOGGER.info(statusMsg);
+        
+        // reduce the message count.
+        this.msgCount--;
+        
+        // Make the current thread to sleep after every Message submission.
+        Thread.sleep(1000);
+      }
+    } catch(InterruptedException ie) {
+      LOGGER.error(ie.getMessage());
+    } catch(Exception e) {
+      LOGGER.error(e.getMessage());
+    }
+  }
+}

queue-load-leveling/src/test/java/org/queue/load/leveling/AppTest.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+/**
+ * Tests that Caching example runs without errors.
+ */
+public class AppTest {
+  @Test
+  public void test() throws IOException {
+    String[] args = {};
+    App.main(args);
+  }
+}

queue-load-leveling/src/test/java/org/queue/load/leveling/MessageQueueTest.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ * 
+ * Test case for submitting and retrieving messages from Blocking Queue.
+ * 
+ */
+public class MessageQueueTest {
+
+  @Test
+  public void messageQueueTest() {
+    
+    MessageQueue msgQueue = new MessageQueue();
+    Message msg = new Message("MessageQueue Test");
+    
+    // submit message
+    msgQueue.submitMsg(msg);
+    
+    // retrieve message
+    assertEquals(msg.getMsg(), msgQueue.retrieveMsg().getMsg());
+  }
+
+}

queue-load-leveling/src/test/java/org/queue/load/leveling/MessageTest.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ * 
+ * Test case for creating and checking the Message.
+ * 
+ */
+public class MessageTest {
+  
+  @Test
+  public void messageTest() {
+    
+    // Parameterized constructor test.
+    String testMsg = "Message Test";
+    Message msg = new Message(testMsg);
+    assertEquals(msg.getMsg(), testMsg);
+
+    // Default constructor and setter method test.
+    Message simpleMsg = new Message();
+    simpleMsg.setMsg(testMsg);
+    assertEquals(simpleMsg.getMsg(), testMsg);
+  }
+}

queue-load-leveling/src/test/java/org/queue/load/leveling/TaskGenSrvExeTest.java

@@ -0,0 +1,50 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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 org.queue.load.leveling;
+
+import org.junit.Test;
+
+/**
+ * 
+ * Test case for submitting Message to Blocking Queue by TaskGenerator
+ * and retrieve the message by ServiceExecutor.
+ * 
+ */
+public class TaskGenSrvExeTest {
+
+  @Test
+  public void taskGeneratorTest() {
+    MessageQueue msgQueue = new MessageQueue();
+    
+    // Create a task generator thread with 1 job to submit.
+    Runnable taskRunnable = new TaskGenerator(msgQueue, 1);
+    Thread taskGenThr = new Thread(taskRunnable);
+    taskGenThr.start();
+    
+    // Create a service executor thread.
+    Runnable srvRunnable = new ServiceExecutor(msgQueue);
+    Thread srvExeThr = new Thread(srvRunnable);
+    srvExeThr.start();
+  }
+
+}