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From John Heitmann <jheitm...@gmail.com>
Subject Re: Network with slow link
Date Wed, 09 Aug 2006 00:22:18 GMT

On Aug 8, 2006, at 6:18 AM, Anders Bengtsson wrote:

> On a related issue, should AMQ detect message loops? Some  
> documentation says
> that it does, by keeping a list of all visited brokers in each  
> message,
> while other documentation (for network TTL) warns about the risk of  
> loops
> with a high network TTL.
> We experienced a few message loops when trying out some more  
> complex broker
> network topologies.

The last I looked into this (late winter, around 4.0-M3 I think)  
there were known issues with some network topologies. True loops  
seemed to be detected ok, but some common non-loop multiple paths  
were not detected. For example if you have a producer to broker A, A  
connected to brokers B1 and B2, B1 and B2 connected only to broker C,  
and you consume from C, then your consumer would see 2 copies of each  
message on a topic.

Since we don't use master/slave and we needed multiple brokers on  
each hop for redundancy we use queues on the paths that would give us  
troubles. Queues ensure that only one path gets a message. The new  
virtual destination functionality will make this kind of setup even  
easier.

John

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