Enterprise JavaBeans, Fourth Edition

EJB 2.1: Message Linking

Message linking is a new feature to EJB 2.1 that allows the messages being sent by any enterprise bean to be routed to a specific message-driven bean in the same deployment. By using message linking, you can orchestrate a flow of messages between components in the same application. For example, in the beginning of this chapter, the TravelAgent EJB from Chapter 11 was re-implemented so that it sent a JMS message with the ticket information to a Topic destination. Here’s a different implementation of the TravelAgent EJB’s bookPassage( ) method, this time using an ObjectMessage type:

public TicketDO bookPassage(CreditCardDO card, double price)
    throws IncompleteConversationalState {
                   
    if (customer == null || cruise == null || cabin == null) {
        throw new IncompleteConversationalState( );
    }
    try {
        ReservationHomeLocal resHome = (ReservationHomeLocal)
            jndiContext.lookup("java:comp/env/ejb/ReservationHomeLocal");
        ReservationLocal reservation =
            resHome.create(customer, cruise, cabin, price, new Date( ));
        Object ref = jndiContext.lookup
            ("java:comp/env/ejb/ProcessPaymentHomeRemote");
        ProcessPaymentHomeRemote ppHome = (ProcessPaymentHomeRemote)
            PortableRemoteObject.narrow(ref, ProcessPaymentHomeRemote.class);
        ProcessPaymentRemote process = ppHome.create( );
        process.byCredit(customer, card, price);

        TicketDO ticket = new TicketDO(customer,cruise,cabin,price);


        TopicConnectionFactory factory = (TopicConnectionFactory)
               jndiContext.lookup("java:comp/env/jms/TopicFactory"); ...