[openstack-dev] [OSLO] Comments/Questions on Messaging Wiki

Russell Bryant rbryant at redhat.com
Mon Jul 15 20:28:09 UTC 2013

On 07/15/2013 02:36 PM, Doug Hellmann wrote:
> The namespace relates to the API implementation inside the receiver. The
> way it currently works is the receiver subscribes to messages on a
> topic/exchange pair to have AMQP route messages to it, and then it looks
> inside the message for further dispatch to an object that knows about
> that API. That lets the nova API implementation be split up among
> different objects, for example. I'm not sure why it evolved that way,
> instead of using separate topics and having the messaging layer do all
> of the routing. Maybe we should take another look at that part of the
> new API design.

In retrospect, yes, a separate topic would have worked.  The namespace
was very convenient for the current nova implementation, but that
doesn't mean it was the best design.  The code that sets up which topics
to consume from is very generic and applies to *all* services.  So,
instead of reworking this to let it be different per-service, I did the
namespace thing, which worked without having to change any other nova code.

Russell Bryant

More information about the OpenStack-dev mailing list