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From Ted Ross <tr...@redhat.com>
Subject Re: looping of qpid routes
Date Thu, 15 Oct 2009 19:18:28 GMT
Which version of the software are you running?

-Ted

H. Charles Tang wrote:
> Thanks folks for your help.
> I think you're telling me that what we did for setting up two routes on a single link
as follows should not cause a msg loop:
> qpid-route route add host1:5000 host2:5000 amq.topic topic.foo
> qpid-route route add host2:5000 host1:5000 amq.topic topic.foo
>
> However what we have observed is different. The msg consumer couldn't 
> keep up with the looping msg and eventually crashed.
>
> Charles
>
> --- On Thu, 10/15/09, Carl Trieloff <cctrieloff@redhat.com> wrote:
>
>   
>> From: Carl Trieloff <cctrieloff@redhat.com>
>> Subject: Re: looping of qpid routes
>> To: users@qpid.apache.org
>> Date: Thursday, October 15, 2009, 9:35 AM
>>
>> 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
>>>
>>>       
>> ---------------------------------------------------------------------
>> 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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