Process a value received by void onMessage() and pass the value to a different function

Question

Scenario

I am consuming messages from a WebLogic Queue by implementing messageListener. The onMessage() call is successful and the message received can be printed from within the onMessage function.

Requirement

To process this msgText as soon as it received and return the processed result to a calling method.

Code

@Override

public void onMessage(Message msg) {

try {
    String msgText;
    if (msg instanceof TextMessage) {
        msgText = ((TextMessage) msg).getText();
    } else {
        msgText = msg.toString();
    }
    System.out.println(msgText);

} catch (JMSException ex) {
    ex.printStackTrace();
}

}

the intention is for a result to be returned to a calling method in another class — ukuta

Miljen Mikic Miljen Mikic · Accepted Answer · 2012-12-06T08:13:17

It is not possible directly because your message-driven bean doesn't have a clue which method posted the message on a message queue and generally there's no callback mechanism in MDBs.

But, there is a trick that can help. It is called TemporaryQueue and it should be used as follows. In the message producer add this portion of code:

// OPEN CONNECTION AND CREATE SESSION
..
TemporaryQueue tempQueue = session.createTemporaryQueue();
msg.setJMSReplyTo(tempQueue);
// SEND MESSAGE
..
MessageConsumer mc = session.createConsumer(tempQueue);
Message retMsg = mc.receive(); //WAITING FOR A RESPONSE..

In consumer (your message-driven bean) use this temporary queue:

Queue destination = (Queue) message.getJMSReplyTo();
// CREATE PRODUCER, CREATE MESSAGE AND SEND THE MESSAGE

This way you will simulate callback mechanism. Object retMsg should contain processed result and you are done.

Process a value received by void onMessage() and pass the value to a different function

Scenario

Requirement

Code

2 Answers