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Hi, 

I came across the implementation of 
https://blueprints.launchpad.net/neutron/+spec/nova-event-callback
and have a question about the way it was implemented.

I notice that now Neutron has a dependency on Nova and needs to be configured
to have nova details (API endpoint, user, password, tenant, etc).
Aside from creating a sort of cyclic dependency between the two, it is my
understanding that Neutron is meant to be a "stand alone" service capable of
being consumed by other compute managers (i.e. oVirt).
This breaks that paradigm.

So my question is: Why use API and not RPC?

I saw that there is already a notification system in Neutron that notifies on
each port update (among other things) which are currently consumed by Ceilometer.
Why not have Nova use those notifications to decide that a VIF got plugged correctly,
floating IPs changed, and so on?

I am willing to make the necessary changes to decouple Neutron from Nova, but
want to understand the rationale behind the original decision of using API
and not RPC notifications.

Regards,
Mike