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Posted to dev@qpid.apache.org by "Cliff Jansen (JIRA)" <qp...@incubator.apache.org> on 2010/05/03 08:36:55 UTC
[jira] Commented: (QPID-2560) WCF to WCF PubSub sample is mis-named
or needs to be re-designed
[ https://issues.apache.org/jira/browse/QPID-2560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12863250#action_12863250 ]
Cliff Jansen commented on QPID-2560:
------------------------------------
The sample is meant to be run by following the recipe in the qpid/wcf/ReadMe.txt file.
In particular, the QCreate commands must be run in advance, and one each of the programs Topic_Producer.exe, Topic_Consumer.exe and Another_Topic_Consumer.exe must be run in the correct order. In this case the sample sends messages via the amq.topic exchange and each consumer receives the whole set of messages.
The sample could surely be improved on many levels, including by dispensing with Another_Topic_Consumer altogether and have Topic_Consumer make external calls to QCreate (or better, qpid-config) to create a unique named queue for each instance, so that arbitrary numbers of consumers could be run at a time.
But since the ability to create temporary queues is one of the next features to be added to the Channel, using that mechanism is probably the more sensible route to follow once it becomes available.
> WCF to WCF PubSub sample is mis-named or needs to be re-designed
> ----------------------------------------------------------------
>
> Key: QPID-2560
> URL: https://issues.apache.org/jira/browse/QPID-2560
> Project: Qpid
> Issue Type: Bug
> Components: WCF/C++ Client
> Affects Versions: 0.7
> Environment: Windows WCF
> Reporter: Ted Ross
>
> The WCF sample called "WCFToWCFPubSub" does not use actual AMQP topic routing and therefore is not an accurate illustration of the publication-subscription pattern.
> The environment in which this was tested was: Two instances of Topic_Consumer and a single instance of Topic_Producer running. The producer sends ten messages and the two consumers receive a subset (partition of the set) of the messages. This is actually using a shared queue and balancing the traffic between the two consumers, not broadcasting the messages equally to the two consumers as it should.
> Another, more fundamental, problem is that the message transfer is layered on top of a remote procedure call handled by a service associated with the consumer. This is why this code example balances the sent messages. It is only possible for an RPC to be handled by a single server.
> RPC is not appropriate for pub-sub since the producer doesn't know, when it produces, how many consumers, if any, there are for each produced message.
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