[openstack-dev] [Solum] Choice of API infrastructure

Doug Hellmann doug.hellmann at dreamhost.com
Tue Nov 5 03:00:57 UTC 2013


On Tue, Nov 5, 2013 at 8:11 AM, Noorul Islam K M <noorul at noorul.com> wrote:

> Doug Hellmann <doug.hellmann at dreamhost.com> writes:
>
> > On Sun, Nov 3, 2013 at 10:54 PM, Jay Pipes <jaypipes at gmail.com> wrote:
> >
> >> On 11/02/2013 11:26 PM, Russell Bryant wrote:
> >>
> >>> On 11/02/2013 11:54 AM, Adrian Otto wrote:
> >>>
> >>>> Noorul,
> >>>>
> >>>> I agree that key decisions should be tracked in blueprints. This is
> the
> >>>> one for this decision which was made in our 2013-10-18 public meeting.
> >>>> Jay's submission is consistent with the direction indicated by the
> team.
> >>>>
> >>>> https://blueprints.launchpad.net/solum/+spec/rest-api-base
> >>>>
> >>>> Transcript log:
> >>>> http://irclogs.solum.io/2013/solum.2013-10-08-16.01.log.html
> >>>> <http://irclogs.solum.io/2013/solum.2013-10-08-16.01.log.html>
> >>>>
> >>>
> >>> Heh, not much discussion there.  :-)
> >>>
> >>
> >> Agreed. I actually didn't know anything about the discussion -- I wasn't
> >> at the meeting. I just figured I would throw some example code up to
> Gerrit
> >> that shows how Falcon can be used for the API plumbing. Like I
> mentioned in
> >> a previous email, I believe it's much easier to discuss things when
> there
> >> is sample code...
> >>
> >>
> >>  Here's my take ... Pecan+WSME has been pushed as the thing to
> >>> standardize on across most OpenStack APIs.  Ceilometer (and maybe
> >>> others?) are already using it.  Others, such as Nova, are planning to
> >>> use it this cycle. [1][2]
> >>>
> >>
> >> I've used both actually, and I've come to prefer Falcon because of its
> >> simplicity and specifically because of the following things:
> >>
> >> * It's lack of integration with WSME, which I don't care for. I don't
> care
> >> for WSME because I believe it tries to put the model at the view layer,
> >> instead of where it belongs, at the model layer.
> >>
> >
> > The "models" defined in WSME are completely different from the database
> > models, and should not be used outside of the API code. Think of them as
> > declaring the models for the consumer of the API, rather than the
> > implementer of the API.
> >
> > The benefits of declaring WSME classes include automatic serialization in
> > JSON and XML, generating WADL files to be included in the API docs (work
> is
> > already happening to make this available for everyone), and consistent
> > input and output types for API endpoints (making it easier for consumers
> of
> > the API to use it and for implementers to validate inputs and assume
> > consistent defaults).
> >
> > And, to be clear, Pecan and WSME are integrated by Pecan can definitely
> be
> > used without WSME. I included WSME in the proposal to replace the
> > home-grown WSGI framework because I thought it added significant
> benefits,
> > but it is not going to be appropriate for all situations (streaming large
> > image files is one example).
> >
> >
> >> * It doesn't need a configuration file, specifically a configuration
> file
> >> that is a Python file as opposed to an .ini file.
> >
> >
> > Pecan does not require a configuration file. It can use one, but we set
> up
> > the WSGI app factory in ceilometer to not use one and I expect the other
> > projects to work the same way.
> >
> >
>
> I see that in ceilometer project has both pypy and py33 gates switched
> off. Is this because of Pecan + WSME? From one of the conversations on
> IRC, it looks like Solum project would like to be py33 compatible from
> the beginning.
>

No, that is not because of Pecan and WSME. The rest of ceilometer is not
yet working on python 3 or pypy, as far as I know.


>
> Having said that, pecan fails to install on pypy and py33. See
> https://review.openstack.org/#/c/55083
>

Pecan tests run under python 3.3 and WSME runs under both python 3.3 and
pypy. It looks like the issue with that changeset is an upstream
dependency. In the past when we've seen that error it had to do with pbr
and versions of setuptools, but I don't know if that's what's going on in
this case.

Doug


>
> Thanks and Regards
> Noorul
>
> > Tuesday (today) at 2:00 there is a session in the Oslo track (
> >
> http://icehousedesignsummit.sched.org/event/b2680d411aa7f5d432438a435ac21fee
> )
> > to discuss tips and pain points with Pecan & WSME. I didn't intend to
> > revisit the decision to start adopting either (we've spent an hour at
> each
> > of the last summits going over that, as well as many email threads), but
> I
> > do want to clear up any other misconceptions and discuss issues with
> either
> > tool so that feedback can be incorporated upstream. Now that both Pecan
> and
> > WSME are on stackforge, we have already had a few patches from OpenStack
> > developers intended to improve and adjust them to meet our needs better.
> >
> > Doug
> >
> >
> >>
> >>
> >>  I care less about the particular choice and more about consistency.  It
> >>> brings a lot of value, such as making it a lot easier for developers to
> >>> jump around between the OpenStack projects.  Can we first at least
> agree
> >>> that there is value in standardizing on *something* for most OpenStack
> >>> APIs?
> >>>
> >>
> >> I completely understand the need for consistency. I pushed my patch as
> an
> >> example of how to do things the Falcon way. While I would prefer Falcon
> >> over Pecan (and certainly over Pecan+WSME), I will respect the push
> towards
> >> consistency if that's what is most important.
> >>
> >> That said, I also believe that the projects in Stackforge should be the
> >> "laboratories of experiment", and these projects may serve as a good
> >> playground for various implementations of things. I remind the reader
> that
> >> over time, the development community has standardized on various things,
> >> only to find a better implementation in an incubated project.
> Pecan+WSME is
> >> actually an example of that experimentation turned accepted standard.
> >>
> >
> >> Best,
> >> -jay
> >>
> >>
> >>  I understand that there may be cases where the needs for an API justify
> >>> being different.  Marconi being more of a data-plane API vs
> >>> control-plane means that performance concerns are much higher, for
> >>> example.
> >>>
> >>> If we agree that consistency is good, does Solum have needs that make
> it
> >>> different than the majority of OpenStack APIs?  IMO, it does not.
> >>>
> >>> Can someone lay out a case for why all OpenStack projects should be
> >>> using Falcon, if that's what you think Solum should use?
> >>>
> >>> Also, is anyone willing to put up the equivalent of Jay's review [3],
> >>> but with Pecan+WSME, to help facilitate the discussion?
> >>>
> >>> [1]
> >>> http://icehousedesignsummit.sched.org/event/
> >>> b2680d411aa7f5d432438a435ac21fee
> >>> [2]
> >>> http://icehousedesignsummit.sched.org/event/
> >>> 4a7316a4f5c6f783e362cbba2644bae2
> >>> [3] https://review.openstack.org/#/c/55040/
> >>>
> >>>
> >>
> >> _______________________________________________
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> >> OpenStack-dev at lists.openstack.org
> >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >>
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
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