OC4J 9.0.4: Problem receiving message from JMS queue

Question

I've created an application which puts XML files in a JMS queue and try to get it out again. The enqueing (sending) is no problem, but when I dequeue from the same queue I receive nothing and if I don't specify a wait time the programs hangs.
If I create a QueueBrowser I can see there are messages in the queue.
Can someone tell me what I do wrong?
Here is the code of my dequeue action:
public String dequeue(int qName) throws RbsSysException
        final String method = "dequeue(int qName)";
        _log.debug(method);
        QueueConnection queueConnection = null;
        try
            queueConnection = _queueConnectionFactory.createQueueConnection();
            QueueSession queueSession = queueConnection.createQueueSession(false,
                    Session.AUTO_ACKNOWLEDGE);
            QueueReceiver queueRcv = queueSession.createReceiver(getQueue(qName));
            _log.debug("queue = "+ queueRcv.getQueue().getQueueName());
            // Due to bug 3376983 in OC4J We cannot use TextMessage if it exceeds
            // 64 kb. Therefore use ObjectMessage.
            Message msg = queueRcv.receiveNoWait();
            _log.debug("msg = " + msg);
            ObjectMessage objMsg = (ObjectMessage)msg;
            //ObjectMessage objMsg = (ObjectMessage) queueRcv.receiveNoWait();
            _log.debug("objMsg = " + objMsg);
            if (objMsg != null)
                return (String) objMsg.getObject();
            else
                return null;
        catch (JMSException je)
            throw new RbsSysException(je);
        finally
            if (queueConnection != null)
                try
                    queueConnection.close();
                catch (Exception any)
                    _log.error("Error while closing QueueConnection: ", any);
    }

Answer 1

Did you implement javax.jms.MessageListener and the method onMessage(Message)?
If you use onMessage() as wel as receive (or receiveNoWait() or receive(long)), the onMessage() can be called, while the main thread is blocking on a synchronous receive, so make sure you use only one of the two methods: onMessage() or receive.
Receive() blocks your thread until a message is published. So your program 'hangs' by design. Usually this is used when your program is waiting for a particular message. Otherwise use onMessage().
ReceiveNoWait() checks if something is in the queue at that very moment, so if nothing is there (yet), the main thread continues.
Hope this helps,
Lonneke