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Date: Sun, 18 May 2008 23:22:34 -0700 (PDT)
From: beaker <beaker222@freenet.de>
To: users@activemq.apache.org
Subject: Re: Detect consumers?
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Hello,

I tried the Advisory Topics, but somehow I can not manage to get any
advisory messages...

I have tested this with a small test server I have found here:
http://coenraets.org/blog/2007/01/flex-test-drive-server-for-java-developers-tomcat-based/

This is a piece of code where I tried to set up a consumer for the advisory
messages:

            ActiveMQDestination topic = (ActiveMQDestination)
context.lookup("ChatTopic");

            Destination advisoryDestination =
AdvisorySupport.getConsumerAdvisoryTopic(topic);

            MessageConsumer consumer =
session.createConsumer(advisoryDestination);

Then I tried to connect some consumers to the topic "ChatTopic", but I never
get an advisory message. Can you tell me what is wrong? Is there maybe some
kind of example or tutorial on how to do this?

Cheers,
beaker


James.Strachan wrote:
> 
> 2008/5/8 beaker <beaker222@freenet.de>:
>>
>>  Hello,
>>
>>  is it possible for a producer to detect, if there are any consumers on
>> the
>>  topic/queue he is sending?
> 
> Yes - you can use advisories...
> http://activemq.apache.org/advisory-message.html
> 
> e.g. try using the ConsumerEventSource helper class...
> http://activemq.apache.org/maven/activemq-core/apidocs/org/apache/activemq/advisory/ConsumerEventSource.html
> 
>>  I want the producer to only send out messages, if there is someone
>> listening
>>  for them.
> 
> We could maybe enhance the JMS client so that it can avoid sending
> messages to topics which have no consumers (i.e. to reduce the cost of
> marshalling the message on the wire and sending it to the broker and
> the broker consuming it).
> 
> -- 
> James
> -------
> http://macstrac.blogspot.com/
> 
> Open Source Integration
> http://open.iona.com
> 
> 

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