[rabbitmq-discuss] Federation with Clusters and Load Balancers

Simon MacMullen simon at rabbitmq.com
Tue Mar 20 11:54:55 GMT 2012

On 19/03/12 18:30, James Carr wrote:
> One more question... is it possible to define an alternate exchange
> for the downstream exchange? Currently I have upstream exchanges that
> any number of message types can be published to  and I'd like a "catch
> all" for the downstream when messages don't get routed.

It's possible to define an alternate exchange since federated exchanges 
are just exchanges, and you can define an alternate exchange on any 

However, the federation plugin goes to some effort to avoid transmitting 
messages that will not be routed, so it won't be much use for messages 
transmitted over the link if you have a federated topic exchange.

You could work around this if you want all messages to be delivered via 
alternate-exchange. Federate a fanout exchange, then bind a topic (or 
whatever) exchange to that with alternate-exchange defined and the 
queues bound to it.

Because the federated exchange is of fanout type the federation plugin 
will federate all the messages for it.

Does this make sense?

Cheers, Simon

Simon MacMullen
RabbitMQ, VMware

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