James.Strachan wrote:
>
> On 1/10/07, JohnRobinson <[EMAIL PROTECTED]> wrote:
>>
>> Hi folks,
>>
>> I'm hoping someone here can help me out. I've got ActiveMQ setup in
>> JBoss,
>> with two queues, one in and one out.
>>
>> I've got one MDB per queue.
>>
>> I'm using the JCA approach for configuring ActiveMQ in JBoss, and I'm
>> using
>> the VM broker.
>>
>> While I have one outbound queue, and one outbound MDB, each message can
>> go
>> to a different destination, and for a variety of reasons its not feasible
>> to
>> create one queue per concrete destination.
>
> -I don't understand what that means :). A queue is a concrete destination?
>
> LOL! Let me see if I can explain. When the message arrives at the MDB it
> is dispatched via a SOAP call to one of several different destinations.
> So I have one outbound queue, one MDB consuming messages from that, and
> when I have a simple case where there is only one destination (and hence
> one group ID) my messages arrive at the destination out of order (each
> message has a sequence number on it).
>
> I've turned on the logging in AMQ via log4j and I see the messages are
> arriving in the queue in order (it would be difficult for them not to, but
> I thought I should check that). Additionally, as the MDB processes the
> messages I put a log statement in that does a toString on the MDB and I
> see multiple instances of the MDB running simultaneously.
>
> The code that sends the message is in a Stateless Session EJB and uses the
> stock JMS apis, not the ActiveMQ apis. It looks like this:
>
> .....
> import javax.jms.JMSException;
> import javax.jms.ObjectMessage;
> import javax.jms.Queue;
> import javax.jms.QueueConnection;
> import javax.jms.QueueConnectionFactory;
> import javax.jms.QueueSender;
> import javax.jms.QueueSession;
> ......
> InitialContext initCtx = new InitialContext();
>
>
> QueueConnectionFactory qcf = (QueueConnectionFactory)
> initCtx.lookup(
> "java:comp/env/jms/QueueConnectionFactory");
>
> QueueConnection qcon = qcf.createQueueConnection();
> String groupId = internalMessage.getGroupId();
> QueueSession qsession = qcon.createQueueSession(true, 0);
>
> Queue q = (Queue) initCtx.lookup(queueName);
> QueueSender qsender = qsession.createSender(q);
>
> ObjectMessage message = qsession.createObjectMessage();
> message.setObject((Serializable) internalMessage);
>
> message.setStringProperty("JMSXGroupID",groupId);
>
> qsender.setTimeToLive(30000);
> qsender.send(message);
> qsender.close();
> qsession.close();
> qcon.close();
>
> Messages are sent to the queue as soon as they are ready, in sequence (1,
> 2, 3, 4, etc) but show up at the SOAP destination out of order (1, 4, 3, 2
> for example) which suggests that they are being processed in parallel.
> The MDB that processes the messages from the queue has a maximum pool size
> of 100. My understanding is that AMQ should be dispatching all of the
> messages for a single group to a single instance of the MDB, allowing
> other instances to process messages to other groups.
>
>> I've been setting the JMSXGroupID on outbound messages but it doesn't
>> appear
>> to be doing any good. Based on my debug output outbound messages to the
>> same target group are handled by multiple instances of the MDB, so
>> messages
>> to the same destination are handled in parallel, which is not what I
>> expected to see with the JMSXGroupID. I was expecting to see that
>> messages
>> to different destinations (in different groups) would be handled in
>> parallel, while messages to the same group would be processed serially.
>
>
> -Hmm, I wonder if there's some issue with the JCA container and Message
> -Groups. Are you sure you are using the same value of JMSXGroupID and
> -messages are being processed concurrently for the same value?
>
> The exact same value is being used for the JMSXGroupID every time. At the
> moment I'm working with a single group.
>
>> Have I misunderstood the expected behavior of groups, or do I just not
>> have
>> it setup properly? I haven't done anything special to enable
>> ExclusiveConsumer, but I see groups are mentioned as an extension of
>> that.
>> Does that mean that ActiveMQ has to be configured for ExclusiveConsumer
>> before grouping will work as expected? If so, how does one do that using
>> the JCA interface, or can one?
>
> -No - the existence of a JMSXGroupID on a message is enough to enable
> -message groups.
>
> That's what I thought.
>
> -I'm wondering if there's some issue with the JCA RA and message
> -groups. You could experiment switching the RA to something like
> -genericjmsra to see if that does any good; or trying switching to the
> -pure JMS client API (rather than MDBs with RAs) to see if that fixes
> -it.
>
> I can try that, in fact I'm going to see if I can replicate this problem
> in a small testbed. But ultimately we want the MDBs as the messages are
> transactional.
>
> Given that groups are implemented in the broker, does the choice of broker
> matter? Should I perhaps be using the tcp broker and starting it
> separately?
>
> --
>
> James
> -------
> http://radio.weblogs.com/0112098/
>
>
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