As discussed in the previous section, interfaces that extend the core JMS interfaces of Queue help build Point-To-Point components.

Please remember that to be able to execute the following example programs, you need the message queue to have been set up.

The following is a sample program to send messages to the Point-To-Point Queue:

package pointtopoint;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueSender;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.InitialContext;

/**
* Program to send messages to the queue
* @author Raja
*
*/
public class QueueMessageSender {
  public static void main(String[] args) {
    QueueMessageSender messageSender = new QueueMessageSender();
    messageSender.enqueueMessage();
  }

  public void enqueueMessage() {
    BufferedReader inlineReader = new BufferedReader(
    new InputStreamReader(System.in));
    try {

      // Prompt for the JNDI Queue connection factory name
      System.out.println("Enter the Queue Connection Factory name:");
      String queueConnFactoryName = inlineReader.readLine();
      System.out.println("Enter the Queue name:");
      String queueName = inlineReader.readLine();

      // Look up for the administered objects of the Queue
      InitialContext context = new InitialContext();
      QueueConnectionFactory queueConnFactory = 
      (QueueConnectionFactory)     
      context.lookup(queueConnFactoryName);
      Queue queueReference = (Queue) context.lookup(queueName);
      context.close();

      // Create the JMS objects from administered objects
      QueueConnection queueConnection =     
      queueConnFactory.createQueueConnection();
      QueueSession queueSession =     
      queueConnection.createQueueSession(false, 
      Session.AUTO_ACKNOWLEDGE);
      QueueSender queueSender =     
      queueSession.createSender(queueReference);

      // Enqueue multiple text messages entered one after the other
      String messageContent = null;
      while (true) {
        System.out.println("Enter the new message to send or 'abandon' 
        to exit the program:");
        messageContent = inlineReader.readLine();
        if ("abandon".equals(messageContent))
        break;
        TextMessage textMessage =     
        queueSession.createTextMessage(messageContent);
        queueSender.send(textMessage);
      }

      // Clean Up
      System.out.println("Messages Successfully 
      posted to the queue...");
      inlineReader.close();
      queueConnection.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

While the preceding program can send messages to the Point-To-Point queue, the following program will keep receiving messages from the queue until the stopReceivingMessages command is received:

package pointtopoint;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueReceiver;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.InitialContext;

/**
* Program to receive messages from the queue
* @author Raja
*
*/
public class QueueMessageReceiver implements MessageListener {
  private boolean stopReceivingMessages = false;

  public static void main(String[] args) {
    QueueMessageReceiver queueMessageReceiver = 
    new QueueMessageReceiver();
    queueMessageReceiver.startReceivingMessages();
  }

  public void startReceivingMessages() {
    BufferedReader inlineReader = new BufferedReader(
    new InputStreamReader(System.in));
    try {

      // Prompt for the JNDI Queue connection factory name
      System.out.println("Enter the Queue Connection Factory name:");
      String queueConnFactoryName = inlineReader.readLine();
      System.out.println("Enter the Queue name:");
      String queueName = inlineReader.readLine();

      // Look up for the administered objects of the Queue
      InitialContext context = new InitialContext();
      QueueConnectionFactory queueConnFactory = 
      (QueueConnectionFactory)     
      context.lookup(queueConnFactoryName);
      Queue queueReference = (Queue) context.lookup(queueName);
      context.close();

      // Create the JMS objects from administered objects
      QueueConnection queueConnection =     
      queueConnFactory.createQueueConnection();
      QueueSession queueSession =     
      queueConnection.createQueueSession(false, 
      Session.AUTO_ACKNOWLEDGE);
      QueueReceiver queueMessageReceiver =     
      queueSession.createReceiver(queueReference);
      queueMessageReceiver.setMessageListener(this);
      queueConnection.start();

      // Keep receiving the messages from the queue until the stop     
      // receiving messages command is received
      while (!stopReceivingMessages) {
        Thread.sleep(1000);
      }

      // Clean Up
      System.out.println("Messages successfully received so far, 
      Stop receiving messages!");
      queueConnection.close();
    } catch (Exception e) {
      e.printStackTrace();
  }
}

public void onMessage(Message message) {
  try {
    String messageContent = ((TextMessage) message).getText();
    System.out.println(messageContent);
    if ("stop".equals(messageContent))
    stopReceivingMessages = true;
    } catch (JMSException e) {
      e.printStackTrace();
      stopReceivingMessages = true;
    }
  }

}