MQSeries Using Java

This is not a tutorial on MQSeries for Java. Instead, you are taken through the steps to how to install and configure MQSeries for Java so that you can develop and test JMS programs. If you don't have these products please download them appropriate Web sites. Also, this is not a detailed tutorial on JMS, though JMS sample code is provided that you can download to test your configuration. We will walk through the sample code to explain what it is doing, and to show you how building and testing JMS programs with the IBM tools allow you to write portable JMS code.

Hardware and software requirements

We will be using the Windows operating system versions of MQSeries for Java, so you'll need to have a computer with the Windows NT operating system and with the Service Pack 6a or Windows 2000 operating system with the Service Pack 1. If you're using Windows NT, make sure you have the latest version of the Microsoft scripting support installed on your computer. The easiest way to ensure this is to install the Internet Explorer 5.5 with the latest Service Pack. You'll need at least 256 MB of RAM and about 1.2 GB of free disk space for the download, install, and application files.

Installing and configuration process of the MQSeries

For Installing and configuration of the MQSeries, please visit installation help

QSender class

There are two classes in the sample code that contain JMS code. They are QSender and the QReceiver. Let go through the important methods in each of these classes and look at how each uses JMS to send and receive messages.

When you look at this classes in the new sample code file provided here, you will see that they differ slightly from the classes in the previous article. Because the no-arg constructor for javax.naming.InitialContext now automatically connects to default name server, I have replaced calls to the constructor that require java.util.Properties argument with calls to the no-arg constructor. This also eliminated the need to provide system properties for the JNDI context factory and JNDI provider address. Since those system properties were no longer required, I also removed system property for the JNDI context name, which is why you must type jms/ before the JNDI names of the administered objects.

The messaging functionality of these classes remains the same as the earlier versions. The QSender class is used by QSenderUI to send messages to a queue. The important methods in QSender are setConnection(), setQueue(), and sendMessage(). Here is the setConnection() method.

The next method to look at is setQueue(). This method is called by the QSenderUI when a Queue name is entered into the GUI. Here is the code for setQueue():

public void setConnection(String connectionName)

							    throws JMSException, NamingException, Throwable {

							    try {

							        close();

							        QueueConnectionFactory factory =

							            
							(QueueConnectionFactory) getInitContext().lookup(

							              
							  getJmsContext() + connectionName);

							        connection = 
							factory.createQueueConnection();

							        session = 
							connection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);

							    } catch (Throwable e) {

							        setExceptionMessage(e);

							        throw e;

							    }

							}

The next method to look at is setQueue(). This method is called by QSenderUI when a Queue name is entered into the GUI. Here is the code for setQueue():

public void setQueue(String queueName)

						    throws JMSException, NamingException, Throwable {

						    try {

						        if (connection != null)

						            
						connection.stop();

						        if (sender != null)

						            sender.close();

						        Queue queue = (Queue) 
						getInitContext().lookup(getJmsContext() + queueName);

						        sender = session.createSender(queue);

						        
						sender.setDeliveryMode(DeliveryMode.NON_PERSISTENT);

						        sender.setPriority(4);

						        sender.setTimeToLive(0);

						        connection.start();

						    } catch (Throwable e) {

						        setExceptionMessage(e);

						        throw e;

						    }

						}

In setQueue(), the first thing to happen is the QueueConnection is stopped and the QueueSender is closed, if needed. Then, the Queue object is retrieved from JNDI based on the queueName parameter. Next, a QueueSender is created to send messages to the Queue, and attributes on the QueueSender are set. Finally, the QueueConnection is started, permitting access to the messaging system. Once again, there is no MQSeries specific code in this method.

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