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From Carl Trieloff <cctriel...@redhat.com>
Subject Re: looping of qpid routes
Date Thu, 15 Oct 2009 14:35:08 GMT

Also, a header is used on the message to prevent loop detection.

Carl.


Jonathan Robie wrote:
> Bidirectional links are fine, and automatically detect loops. Tree, 
> star, or line topologies are fine too, and bidirectional links between 
> any pair of brokers are fine. A ring topology is also possible, if 
> only unidirectional links are used.
>
> Here's the rule:
>
> For any pair of nodes A,B in a federated network, there should be only 
> one path from A to B. If there is more than one path, message loops 
> can cause duplicate message transmission and flood the federated 
> network. The topologies discussed above do not have message loops. A 
> ring topology with bidirectional links is one example of a topology 
> that does cause this problem, because a given broker can receive the 
> same message from two different brokers. Mesh topologies can also 
> cause this problem.
>
> Every message transfer takes time. For better performance, you should 
> minimize the number of brokers between the message origin and final 
> destination. In most cases, tree or star topologies do this best.
>
> Hope this helps!
>
> Jonathan
>
> H. Charles Tang wrote:
>> Have created 2 static routes as follows between our 2 qpid daemons 
>> housed on two linux hosts respectively:
>> qpid-route route add host1:5000 host2:5000 amq.topic topic.foo
>> qpid-route route add host2:5000 host1:5000 amq.topic topic.foo
>>
>> Does this create an infinite loop for a message between 2 qpids? Our 
>> experiment confirmed the looping scenario.
>> Then how does one create a bi-directional route? or how do we 
>> interpret the following in the qpid documentation:
>> "Routes are unidirectional. A single route provides for the flow of 
>> messages in one direction across a link. If bidirectional 
>> connectivity is required (and it almost always is), then a pair of 
>> routes must be created, one for each direction of message flow."
>>
>> Finally does qpid (daemon) do loop detection/handling?
>>
>> Thanks.
>> Charles
>>
>>
>> ---------------------------------------------------------------------
>> Apache Qpid - AMQP Messaging Implementation
>> Project:      http://qpid.apache.org
>> Use/Interact: mailto:users-subscribe@qpid.apache.org
>>
>>
>>   
>
>
> ---------------------------------------------------------------------
> Apache Qpid - AMQP Messaging Implementation
> Project:      http://qpid.apache.org
> Use/Interact: mailto:users-subscribe@qpid.apache.org
>


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