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From Aleksandar Ivanisevic <aleksan...@ivanisevic.de>
Subject Re: STOMP SUBSCRIBE and UNSUBSCRIBE behaviour
Date Mon, 17 Oct 2011 11:14:57 GMT
Steve Powell <spowell@vmware.com> writes:

> On 28 Sep 2011, at 20:40, tabish121@gmail.com [via ActiveMQ] wrote:
>> Can you clarify what it is you want to know, the stomp spec defines this 
>> pretty clearly already, what part do you need help with? 
>
> Durable topic subscriptions are not described in the STOMP spec.
> My questions relate to ActiveMQ/Apollo STOMP behaviour.

I'm not sure AMQ and Apollo are the same. I can tell you what happens
in AMQ, derived from my empirical observations, since, as you noted,
the documentation is not really useful when we are into details.

> Specifically: if a SUBSCRIBE id:id01;destination:/topic/foo;persistent:true;; is issued
> when an EXISTING global id:id01; destination:/topic/bah;persistent:true;; already exists,
> what happens to active subscribers of the id01 subscription?
>
> This is a repeat subscription with a different topic but the same
> id.

subscriptions are identified with client id and subscription id, not
by destination, so those two will be different if issued from
different client ids. Otherwise you will get kicked out with
javax.jms.InvalidClientIDException.

> Also: if an UNSUBSCRIBE id:id01;persistent:true;; is issued what happens to existing
> active subscribers of the durable subscription id01?
>
> This is an UNSUBSCRIBE of a durable topic subscription

I wasn't able to unsubscribe a durable subscriber from AMQ via STOMP
no matter what I did. The only way to kill a subscription was to
delete it in the web interface.

I've reported it here, but was asked to provide a unit test. Since I'm
an admin and not really familiar with all the tools used in the modern
Java development (took me couple of days just to get AMQ built) I'm
guessing it will take me another couple of months to create a test
case ;)

> The STOMP spec is silent on all semantic issues and the ActiveMQ Apollo specification
> seems to imply that the subscription is destroyed when the UNSUBSCRIBE is issued,
> but it doesn't say what is supposed to happen when a distinct topic destination is
> defined for an existing durable topic subscription.

In AMQ destination doesn't matter, see above.



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