On 2018-11-09, 8:37 PM, "netmod on behalf of Martin Bjorklund"
<netmod-boun...@ietf.org on behalf of m...@tail-f.com> wrote:
Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de> wrote:
> On Thu, Nov 08, 2018 at 10:42:20PM +0100, Martin Bjorklund wrote:
> > Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de> wrote:
> > > On Sat, Oct 27, 2018 at 06:50:58AM -0700, Andy Bierman wrote:
> > > >
> > > > This is what we have today only if modules are updated in legal
ways.
> > > > The 3.1 requirement says this backward compatibility is maintained
even
> > > > if the module is updated in violation of the module update rules.
> > > >
> > >
> > > It is stating a requirement. How solutions meet the requirement is for
> > > the solutions to figure out.
> > >
> > > > How would 3.1 be met if the WG decided to just add a new 'datastore'
> > > > key leaf to the /modules-state/module list?
> > >
> > > Depends on the solution I guess.
> > >
> > > > IMO the current "deprecate and start over" is actually the easiest
> > > > and most robust solution path, and it requires no changes to YANG or
> > > > the protocols.
> > >
> > > Yep. But there are people who think that other solutions can do
> > > better. The challenge is to find out whether they actually do better
> > > or for whom they do better (and if someone has to pay a price for it).
> > > For having this discussions, it is good to write down requirements.
> > >
> > > > > 3.2 The solution MUST provide a mechanism to allow
servers to
> > > > > simultaneously support clients using different
revisions of
> > > > > modules. A client's choice of particular revision of
one or
> > > > > more modules may restrict the particular revision of
other
> > > > > modules that may be used in the same request or
session.
> > > > >
> > > > > Today, the version number is effectively an (implicit) part of the
> > > > > module name (plus the revision date for backwards compatible
changes).
> > > > > Hence, my understanding is that today's model does satisfy 3.2 as
> > > > > well.
> > > >
> > > > This is not what we have at all. RFC 7950 says a server can only
implement
> > > > one revision of a module.
> > > >
> > >
> > > A new version today essentially means a new module name and I do not
> > > see a conflict with what I wrote.
> >
> > Then I think this requirement needs clarification. It says "different
> > revision of modules", which can be interpreted as different revisions
> > of *the same* module.
> >
> > Also the second part of the paragraph seems to indicate multiple
> > revisions of the same module in the server.
> >
> > I do not agree with this requirement.
>
> Today, you need to create a new module if you make NBC changes to
> existing changes (e.g., you change Bool to Int {0..1} and you are not
> creating a new leaf). Since there are now two modules, you _can_
> implement both modules if that makes sense.
Yes.
> If we allow to make such changes as part of a module revision, i.e.,
> without creating a new module, I think we should not loose the ability
> to implement both the old version and the new version.
I don't think we should allow such changes, and if we did, I don't
think that both revisions should be implemented at the same time. I
think the overall solution would just be too complex.
> I think we need to distinguish between the agreement on the
> requirement, namely that a server should be able to provide support
> for an old and a new definition, and agreement on the solution.
>
> Do you disagree with the requirement? Or do you disagree with the
> consequences of implementing multiple versions of the same module
> for some of the proposed new versioning schemes? Or both?
I do not agree with the requirement that a server MUST be able to
support multiple revisions of the same module, which is how I
interpret 3.2. If this is not the intention of 3.2, maybe it can be
clarified.
<RR> It says "The solution MUST provide...", so the solution draft MUST provide
a solution on how to do this. Whether a server implements the solution or not
is a different matter. We realize this is a pain for most servers but some
servers may be able to do it.
Regards,
Reshad.
/martin
>
> /js
>
> --
> Juergen Schoenwaelder Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany
> Fax: +49 421 200 3103 <https://www.jacobs-university.de/>
>
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