[rabbitmq-discuss] federation plugin: x-federation exchange declaring

Mon Sep 17 11:56:17 BST 2012

Hi,

I am not quite sure, that I am understanding federation plugin well. But my 
case is following:

I have one setup "A": the rabbitmq-server, and a few clients, which are 
communicating with each other.

Then I need to clone this on the other hardware at the different place. Say 
setup "B". And there is one exception, one of my 'direct' exchanges must be 
common for this two setups. I've set up federation plugin on "B", it has 
been connected to "A" and everything seems to be ok so far.

My python clients fail at "B" with the following error:

pika.exceptions.AMQPChannelError: (406, "PRECONDITION_FAILED - cannot 
redeclare exchange 'my-exchange' in vhost '/' with different type, durable, 
internal or autodelete value")

This is because they are pub/sub subscribers. I declare the exchange, bind 
to it, and wait for incoming messages. Obviously, It is somehow connected 
with that 'my-echange' has been already created by federation-plugin.

Is there a way to avoid modification of client code to keep same versions of 
my python clients on both "A" and "B"? Where 'my-exchange' is 'direct' and 
'x-federation' with backtype 'direct' respectively.