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Hi Mark

Nova takes approach 2 so we should use same way.
In Nova, notification is for outside system, so the functionalities is
not used in modules.
Basically, Notification can't support transaction by the concept.
However, we can use rpc.call,which returens exceptions to caller from callee.

I'm a fun of polling. ( IMO, it should use REST API not direct
connection to the DB)

DB.poll has merit on the view of Transactions.
Even if dhcp process CRUD fails, it will update processes.


2012/8/9 Mark McClain <mark.mcclain at dreamhost.com>:
> All-
>
> I wanted to widen the discussion that we've been having on https://review.openstack.org/#/c/10997/
>
> Basically the DHCP Agent needs to be notified about certain Quantum events.  There are two ways of accomplishing this:
>
> 1) Turn on Quantum notifications and have the agent consume the general notifications.  Moving forward this would require that rabbit_notifications always be enabled in quantum.conf.
>
> Pro: This functionality already exists in Quantum.
> Con: These messages are more general, so the agent typically has to collect some data in response to the calls.
>
> Note: The rabbit_notifier actually works will all of the messaging backends, i.e. qpid.)  These messages are more general in nature and just provide the data returned from the plugin.
>
> 2) Create specific RPC calls that q-svc fans out to the DHCP agent(s).
>
> Pro: This approach means that the Quantum server can send messages that are specifically tailored for the DHCP agent to act upon.
> Con: Essentially implements a subset of the notification API in a specific way.
>
> I'm open to either approach, but would like the community's input. Thoughts?
>
> mark
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