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Re: [smila-dev] new router/listener 
Hi Juergen,

Juergen.Schumacher@xxxxxxxxxxx wrote:

Hi,
I agree with Sebastian that a listener should only read those message it really wants to process and not all messages, so we need to use message selectors. It may be "our" queue with only "our" message, but still we could have specialized workflow processors that provide only a selection of all workflows, so they should not read messages that they cannot process because they do not contain the needed workflow. 


Agree.
Why do you say that the syntax for message selectors is not defined in JMS? There is a syntax specification 
in [1]. Or am I confusing something and you mean something different?


So, I was wrong, many thanks.
Idea - we may try to extract and use message selector SQL evaluator implementation from ActiveMQ to use in Router instead of beanshell.
Also, Derby is surely not an appropriate database when it comes to really high volume scenarios, so we should do tests with "real" database servers, too. BTW, why do we use Derby at all? The default message store in ActiveMQ should be a file based storage [2], which should provide better performance (at least they claim it). 


Yes you are right its file based storage used here
I saw this performance problem and mix up ActiveMQ with other framework - it was not a my day :(. 


Cheers,
Juergen.
[1] http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/jms/Message.html 
[2] http://activemq.apache.org/amq-message-store.html
BTW: new router/listener already integrated and working, old version is removed. 

--
Regards, Ivan



    ------------------------------------------------------------------------
    *From:* smila-dev-bounces@xxxxxxxxxxx
    [mailto:smila-dev-bounces@xxxxxxxxxxx] *On Behalf Of *Sebastian Voigt
    *Sent:* Thursday, July 31, 2008 5:16 PM
    *To:* Smila project developer mailing list
    *Subject:* RE: [smila-dev] new router/listener

    We should use the Queue for Remote Communication and therefore we
    should use Queries to get Entries from the Queue.

    (instead to have a central listener that distribute the entries to
    the workflow processes (distributed systems!)).

    Please use for the first implementation configurable timeout values

    (it should be no problem to use higher values than 1 second, or?)


    Mit freundlichen Grüßen / Kind regards

    Sebastian Voigt

    *brox *IT-Solutions GmbH*

    *

    ==================================
    According to Section 80 of the German Corporation Act brox
    IT-Solutions GmbH must indicate the following information.
    Address: An der Breiten Wiese 9, 30625 Hannover Germany
    General Manager: Hans-Chr. Brockmann
    Registered Office: Hannover, Commercial Register Hannover HRB 59240
    ========== Legal Disclaimer ==========


    *From:* smila-dev-bounces@xxxxxxxxxxx
    [mailto:smila-dev-bounces@xxxxxxxxxxx] *On Behalf Of *Ivan Churkin
    *Sent:* Wednesday, July 30, 2008 4:12 PM
    *To:* smila-dev@xxxxxxxxxxx
    *Subject:* [smila-dev] new router/listener


    Hi Sebastian


    Router/Listener based on new principles is working.
    /(Its possible to manage working threads by JMX, using multiples
    brokers, switching MQ implementations and specifying task
    execution list in configuration.)
    (Its not included into main build and not used by connectivity etc.)
    /
    For testing include into workspace all new bundles from trunc
    /org.beanshell
    org.eclipse.eilf.jms
    org.eclipse.eilf.jms.activemq
    org.eclipse.eilf.connectivity.queue.worker
    org.eclipse.eilf.connectivity.queue.worker.test
    /
    Test it by running launch configuration
    /org.eclipse.eilf.connectivity.queue.worker.test/WorkerTest.launch/



    It was found a problem with ActiveMQ
    /I pushed into queue just only 2500 messages before listening
    and after that consumer was unable to receive messages.
    I guess that it was because now consumer collect messages
    synchronously in working thread
       message = _consumer.receive(TIMEOUT);
    (TIMEOUT was equals to 1 sec)
    /*
    I think that ActiveMQ is unable to find message in durable storage
    by Condition in this timeout and always return NULL!*

    Solutions:
    /1) I did TIMEOUT configurable by Rule XML tag, increase it and to
    forget.
    2) We may try to use more fast database when Derby as ActiveMQ
    durable message storage.
    /But all that solutions are only partial.

    There is totally different solution:
    /To get message from consumer without condition and to check
    Condition inside Listener.
    That also helps to solve the second problem: "Condition syntax
    does not specified in JMS and depends on broker implementation"
    In this solution condition syntax in Rules will be independent
    from broker implementation.
    /
    But, of course, there is also a disadvantage:
    /Listener will get every message from queue and, if rule will not
    be found, message will be send into DLQ, finally.
    But I'm not sure that its a problem because its "our queue" and it
    should contains only "our messages".
    /
    What do you think about it?
    Folks, feedbacks are appreciated :).

    --
    Regards, Ivan

------------------------------------------------------------------------

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