JMS和MessageDriven EJB Bean

Question

I have a problem with message driven EJB. I have too applications Web Service and EJB application which contains MessageDrivenBean.

To send message to JMS I'm using ObjectMessage: Here is my code:

        Connection connection = connectionFactory.createConnection();
        Session session = connection.createSession(false, 1);
        MessageProducer messageProducer = session.createProducer(queue);
        ObjectMessage outMessage = session.createObjectMessage();
        outMessage.setObject(((Serializable) operation));
        LOGGER.debug("Sending message...");
        messageProducer.send(outMessage);
        LOGGER.debug("Sending message: done.");
        messageProducer.close();
        session.close();
        connection.close();

When I call my web service I am calling this method as well. The message arives at MDB and starts to process. Here is my MDB code:

    @MessageDriven(mappedName = "jms/cbsDestination", activationConfig = {
        @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"),
        @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue")
})
    public class OperationsBackgroundService implements MessageListener {
          //Some code....
         public void onMessage(Message message) {
    LOGGER.debug("Got message: " + message.toString());
    if (message instanceof ObjectMessage) {

        ObjectMessage objectMessage = (ObjectMessage) message;
        Operation operation = null;
    }

Its all OK, I get the message, it starts to process and it ends as I expect.

But the problem is: When I send first message to MDB it starts process it (OK), then, when first message is processing I send second message to my MDB, and it starts processes it as well. Ass I know the JMS is characterized by that if I send one message and that one is processing, other messages waits until the first is processed. Or am I missing something here? Please help. Maybe there is some properties I forgot to set?

Thanks id advance.

Answer 1

Your application server created more than one instance of OperationsBackgroundService and registered each instance as a consumer. Each consumer can only process one message at a time, but when there are, say, 2 consumers, 2 messages can be processed concurrently. This is a feature, not a bug.

If you want to achieve single-threaded processing, simply tell your application server to create only one consumer per MDB. Consult your application server documentation to see how this can be configured.