On Tue, Nov 29, 2011 at 11:39:08AM -0800, Chris Wright wrote:
> * Adam Litke (a...@us.ibm.com) wrote:
> > 
> > https://github.com/aglitke/vdsm-rest/
> > 
> > Today I am releasing a proof of concept implementation of a REST API for 
> > vdsm.
> > You can find the code on github.  My goal is to eventually replace the 
> > current
> > xmlrpc interface with a REST API.  Once completed, ovirt-engine could 
> > switch to
> > this new API.  The major advantages to making this change are: 1) VDSM will 
> > gain
> > a structured API that conceptually, structurally, and functionally aligns 
> > with
> > the ovirt-engine REST API, 2) this new API can be made public, thus 
> > providing an
> > entry point for direct virtualization management@the node level.
> Adam, this looks like a nice PoC.  I didn't see how API versioning is
> handled.  Any VDSM developers willing to review this work?

Thanks for taking a look.  I am not handling versioning yet.  I think we can add
a version field to the root API object.  As for compatibility, we'll just have
to decide on an API backwards-compat support policy.  Would this be enough to
handle versioning issues?  We shouldn't need anything like capabilities because
the API is discoverable.

> <snip>
> > ovirt-engine wants to subscribe to asynchronous events.  REST APIs do not
> > typically support async events and instead rely on polling of resources.  I 
> > am
> > investigating what options are available for supporting async events via 
> > REST.
> I think typical is either polling or long polling.  If it's a single
> resource, then perhaps long polling would be fine (won't be a large
> number of connections tied up if it's only a single resource).

Not sure if this is what you are referring to, but I was thinking we could do a
batch-polling mechanism where an API user passes in a list of task UUIDs and/or
event URIs.  The server would respond with the status of these resources in one
response.  I have some ideas on how we could wire up asynchronous events on the
server side to reduce the amount of actual work that such a batch-polling
operation would require.

Adam Litke <a...@us.ibm.com>
IBM Linux Technology Center

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