JMS and 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.

Tomasz Nurkiewicz Tomasz Nurkiewicz · Accepted Answer · 2012-02-05T20:35:43

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.

JMS and MessageDriven EJB Bean

1 Answers