Re: [netmod] schema mount and YANG library

[Martin Bjorklund <[e-mail]>]

Lou Berger <[e-mail]> wrote:
> 
> 
> On 1/16/2018 8:50 AM, Martin Bjorklund wrote:
> > Lou Berger <[e-mail]> wrote:
> >>
> >> On January 16, 2018 8:24:42 AM Martin Bjorklund <[e-mail]>
> >> wrote:
> >>
> >>> Lou Berger <[e-mail]> wrote:
> >>>> Lada,
> >>>>
> >>>>
> >>>> On January 16, 2018 7:07:15 AM Ladislav Lhotka <[e-mail]> wrote:
> >>>>
> >>>>> On Tue, 2018-01-16 at 06:30 -0500, Lou Berger wrote:
> >>>>>> Lada,
> >>>>>>
> >>>>>> It sounds like you are proposing in (1) a fairly significant change in
> >>>>>> the
> >>>>>> direction of the draft and in (2) a basic approach that has been
> >>>>> It is no change in direction, just a simplification of the
> >>>>> schema-describing
> >>>>> state data. Given the recent developments in 7895bis it makes no sense
> >>>>> to me to
> >>>>> have two "schema" lists if we can have just one.
> >>>>>
> >>>> Managing transition is hard. It's also highlights why Yang Library
> >>>> this needs to be at least equally discussed in this group.
> >>>>
> >>>> I will talk with my co-chairs and perhaps the ADs to get their opinion
> >>>> on making such a change this point in the process.
> >>>>
> >>>>
> >>>>>> rejectected by the WG multiple times.  FWIW there are drafts already
> >>>>>> with
> >>>>> No at all. The first and last time I proposed this was on 15 December
> >>>>> 2017:
> >>>>>
> >>>>> https://www.ietf.org/mail-archive/web/netmod/current/msg19753.html
> >>>>>
> >>>> Oh, I certainly would call you proposing that the schema for inline be
> >>>> part of the rest of the schema Mount module well before that. I'm sure
> >>>> I can dig up mail / slides it really necessary...
> >>> I don't think this has been proposed before.  All previous proposals
> >>> were basically variants on what is now "use-schema", which works fine
> >>> when all instances have the same schema.  This new proposal solves the
> >>> issue with different schemas in different instances.
> >>>
> >> I thought the previous proposals that as well, so don't see material
> >> difference - at least from the usage standpoint. I also don't see why
> >> the previous arguments that resulted in consensus for using Yang
> >> Library underneath the an in line Mount Point don't apply.
> > B/c it doesn't work well with the NMDA.  You can't mount yang library
> > in the configuration datastores; it has to be mounted in operational.
> > With meta-data, you can actually report the correct schema even in
> > running.  (This is actually true also for pre-NMDA systems).
> >
> Understood and agree there is nothing new here and the current version
> of SM (including inline) has the same limitation as rfc7895, and I'd
> expect it to behave the same once we have rfc7985bis -- in fact the
> inline case "just works" with YL-bis as defined today.
> 
> The argument I recall being the key point on inline was handling the
> large variety of possible different implementation approaches for
> modules using inline.

I think these still are covered.

> For example an LNE that is implemented using
> VMs which can be managed by the host at different times of the VMs
> operational life cycle based on customer/provider requirements.  I
> really don't see how YL-bis has any bearing on this point and

Using the new proposed meta data annotation together with the new YL
means that SM can support the use case above also in an NMDA server.
I think the new proposed solution covers more use cases than the
previous solution.

Do you think that there is any use case that the proposed solution
cannot handle, but the previous solution did?

> I think
> it is incumbent upon those revisiting past/closed WG decisions (in
> this case, inline schema being represented by YL) to argue why the
> decision needs to be revisited.

I'm repeating my self: b/c the current solution doesn't work well with
the NMDA.


/martin