Open Stack

On 10/15/2014 11:49 AM, Kevin L. Mitchell wrote:
> Now that we have an API working group forming, I'd like to kick off some
> discussion over one point I'd really like to see our APIs using (and
> I'll probably drop it in to the repo once that gets fully set up): the
> difference between synchronous and asynchronous operations.  Using nova
> as an example—right now, if you kick off a long-running operation, such
> as a server create or a reboot, you watch the resource itself to
> determine the status of the operation.  What I'd like to propose is that
> future APIs use a separate "operation" resource to track status
> information on the particular operation.  For instance, if we were to
> rebuild the nova API with this idea in mind, booting a new server would
> give you a server handle and an operation handle; querying the server
> resource would give you summary information about the state of the
> server (running, not running) and pending operations, while querying the
> operation would give you detailed information about the status of the
> operation.  As another example, issuing a reboot would give you the
> operation handle; you'd see the operation in a queue on the server
> resource, but the actual state of the operation itself would be listed
> on that operation.  As a side effect, this would allow us (not require,
> though) to queue up operations on a resource, and allow us to cancel an
> operation that has not yet been started.
>
> Thoughts?
I'd like to couple this approach with a a greater use of Keystone trusts 
for delegation of authority.  Trusts and async calls are designed to 
work together.