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From Nicky Sandhu <>
Subject Re: How to have a highly available and scalable setup using network of brokers?
Date Thu, 21 Jun 2007 15:43:31 GMT

Joel Schaubert wrote:
> What I have found during my testing of the network of brokers is that you
> do get this behaviour.  If I write 100 message to broker A, then I kill
> it, then I subscribe to broker B, I can read all of the messages. (and
> various versions of this scenario tested in our QA environment).
Interesting. That means the broker A is pushing messages to broker B before
sending publisher the ack. Thats quite an overhead. Or is broker A somehow
sharing the message store with broker B? I thought the forwarding was on a
demand based policy. Did you configure it differently?

Joel Schaubert wrote:
>   What's also nice about this is unlike master/slave, when broker A comes
> back up it will be noticed by the load balancer and can take any new
> client connections then.  Read the section on how to do recovery on a
> failed master in master slave, it doesn't sound anywhere near as easy as a
> network of brokers behind a load balancer.
 I agree. If what you are saying works then I have no need for M/S
configuration and the headaches of recovery.

Joel Schaubert wrote:
> One thing to note if you try network of brokers is that the auto discovery
> is very complete.  So if you had 2 different networks of brokers I don't
> think auto discovery is useful because they would all join up into one big
> network.  For example if you had one network in production, one for QA, I
> think the autodiscovery would have every broker find every other broker. 
> We are testing the method where you statically list each of the other
> brokers you want to participate with.
 I believe James is saying that you can write your own discovery policy. So
a discovery agent based on some service that tells it what brokers are
willing to join in that network should work in the above scenario. 

 Also I am no expert in multicast, but I think you can specify a different
host /port combination in the multicast discovery configuration between prod
and QA brokers and that would partition the brokers as such.
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