Open Stack

On Fri, 2013-06-14 at 09:52 +1200, Robert Collins wrote:
> On 14 June 2013 09:50, Kevin L. Mitchell <kevin.mitchell at rackspace.com> wrote:
> > Thoughts?
> 
> How/why is a cell different from a node in this respect? [Serious question].

So, for inter-node communication within a given nova instance (cell),
there is a single Rabbit queue (or whatever) that all the nova services
connect to.  Since there's only one, this queue can be identified via
configuration.

With cells, it's different; each cell essentially has its own queue that
it listens to.  (This could be the single Rabbit queue that all its
services listen to, I think, or could be something totally different
reserved solely for inter-cell communication.)  This means that, for one
cell to talk to another, it must know how to talk to that other cell,
and thus that data must be bound together with the information about
what cells exist.  At present, we do this through the database.

Make sense?
-- 
Kevin L. Mitchell <kevin.mitchell at rackspace.com>