openstack team mailing list archive

[Dan Wendlandt <dan@xxxxxxxxxx>]

Hi Irena, Bob, Salvatore,

Just catching up the thread, and looping the netstack and openstack lists
in as well, as this info is general useful in my opinion.

Our model with Quantum, like Nova, is that it is definitely ok to extend
the content of a core object with additional attributes.  These attributes
should be formatted properly as extended attribute, so that the "key" of
the attribute is <extension-alias>:<attribute-name>

This is done pretty commonly within Nova.  Two simple examples are:
- nova/api/openstack/compute/contrib/scheduler_hints.py
- nova/api/openstack/compute/contrib/extended_status.py

I do not believe you need to (or should) modify the view-builder code for
the core object when you want to add an extended attribute to it.  Instead,
the extension framework has you write a wsgi controller specific to the
extension that is inserted as its own stage into the wsgi request and
response processing pipeline.  Thus, when the request is passed in, your
code gets a chance to parse the data, and the the response is passed back,
your code gets a chance to add data to it.

Using the Nova code as example is probably the best bet if you can find a
good example within quantum.  Quantum's extension framework (and several
other openstack projects) all use essentially the same model.

Dan


On Sat, Jun 2, 2012 at 8:43 AM, Robert Kukura <rkukura@xxxxxxxxxx> wrote:

> On 06/02/2012 05:02 AM, Irena Berezovsky wrote:
> > Hi,
> > Bob, Dan,
> > I ran into following wiki page:
> >
> http://wiki.openstack.org/QuantumAPIExtensionsaction=AttachFile&do=view&target=quantum_api_extension.pdf
> > 'port profile' is exactly what I was looking for to expose in the plugin.
> > I would like to add the port profile retrieval capability and contribute
> the implementation.
> >
> > Can you please advise if there is any disagreement on getting it into
> core API? Shall I do it via extension?
> > Bob, seems that you are dealing with similar issues.
> > What do you suggest?
> >
> > Thanks a lot,
> > Irena
>
> Irena,
>
> I'm not sure there is any consensus around using a "network profile" for
> this. I did see that document as well as archived discussion about
> defining "port profile" and "network profile" as extensible collections
> of attributes. But the existing "port profile" extension looks to be
> Cisco-specific, and seems to serve a somewhat different purpose.
>
> My current thinking is that we'd be better off long term following the
> lead of Nova and other projects in supporting "extension data" within
> the existing resources instead of requiring introduction of a new
> resource just to hold plugin-specific attributes.
>
> But, in the short term, it might make the most sense for each extension
> just to provide its own resource extension with its attributes. That's
> what I'm tentatively planning to do for the provider-network blueprint,
> but would reconsider if there was consensus that either the "extension
> data" support or a more general "network profile" should be added now.
>
> -Bob
>



-- 
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Dan Wendlandt
Nicira, Inc: www.nicira.com
twitter: danwendlandt
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