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Friday November 25, 2005

How to develop JMS client in NetBeans I will describe developing of a client application that send JMS message with order. The order will be processed in application tier. Since, I would like to conform patterns, I will use business pattern that separates presentations from business logic. I would like to describe this pattern in one of the next posts. Specifically, a business delegate is a helper class that handles the details of connecting and sending JMS message. GUI invokes methods in business delegate class and isn't interested in low-level stuff. :-) Let's start to create J2SE client:

• Create new J2SE project
• Now, we should add all requested libraries on classpath. Therefore, add folowing jars on projects classpath: $SUN_APP/lib/j2ee.jar, $SUN_APP/lib/appserv-admin.jar, $SUN_APP/lib/appserv-rt.jar, $SUN_APP/lib/install/applications/jmsra/imqjmsra.jar. Of, course we shouldn't forget to add OrderLib project on classpath as well. We will send Order transfer object that is shared between client and EJB module.
• It's good practice create interface BusinessDelegate with all business methods and then implement it in concrete business delegate class. With this approach we can simple add new implementation of business delegate, e.g. communicate with app tier with web service,... Folowing is code of business delegate class:

       public class DelegateImpl implements OrderDelegate{
       private static String JMS_FACTORY_NAME = "jms/ProcessOrderDestinationFactory";
       private static String QUEUE_NAME = "jms/ProcessOrderBean";
  
       public DelegateImpl() throws ApplicationException{
          try{
          ctx = new InitialContext();
          connFactory = (TopicConnectionFactory) ctx.lookup(JMS_FACTORY_NAME);
          destination = (Topic) ctx.lookup(QUEUE_NAME);
          }catch(NamingException ex){
              throw new ApplicationException(ex.getMessage());
          }
       }
  
        public void createOrder(Order order) throws ApplicationException{
          Connection conn = null;
          MessageProducer producer;
          try {
              conn = connFactory.createConnection();
              Session session = conn.createSession(false,
                      Session.AUTO_ACKNOWLEDGE);
              producer = session.createProducer(destination);
              ObjectMessage objMsg = session.createObjectMessage();
              objMsg.setObject(order);
              producer.send(objMsg);
              if(conn != null){
                  conn.close();
              }
          } catch (JMSException ex) {
              throw new ApplicationException(ex.getMessage());
          }
         }
     

• Then, we might create GUI for order and test it.
Sources are avalaible here. Note, If you want to run this client on other machine then Appp server is located, simple use JVM options that were used in EJB client post.