Re: [netmod] schema mount and YANG library

[Ladislav Lhotka <[e-mail]>]

On Thu, 2018-01-18 at 08:56 +0100, Martin Bjorklund wrote:
> Lou Berger <[e-mail]> wrote:
> > 
> > 
> > On 1/17/2018 11:18 AM, Martin Bjorklund wrote:
> > ...
> > > > > My main concern is actually the YL version.  I strongly think SM need
> > > > > to use YL-bis rather that the old YL, so that it can support NMDA.
> > > > > 
> > > > 
> > > > Right now to SM is independent of Yang Library version and can run
> > > > with either.
> > > 
> > > No this is not correct.  SM uses a grouping from the old YANG
> > > library (for the "use-schema" case),
> > 
> > I thought YLbis was an updat e to UL (i.e., no name change) as such SM
> > can include either.
> 
> The old "modules-state" structure is deprecated, and a new structure
> that allows multiple datastores is defined.  Note that YLbis can be
> used by both NMDA-capabale and non-NMDA-capabale servers.

This is another reason to switch to the @schema-ref annotation, because
otherwise YLbis is unnecessarily complex and inefficient to be used under each
inline mount point instance, with the module-sets and datastore lists.

Lada

> 
> > >   and talks about mounting
> > > "modules-state" ("inline" case).
> > 
> > In informative descriptions only.  Certainly these can be changed to
> > allow for YL-bis if need be.
> > 
> > > > I certainly would expect use of Yang Library bis and nmda
> > > > to have advantages.
> > > > 
> > > > > The implementation effort for supporting the new YL in clients and
> > > > > servers is minimal, esp. when compared to the efforts involved in
> > > > > supporting SM.
> > > > > 
> > > > > Adding an indirection is (for me) less important, but it has the
> > > > > benefit of solving the two issues (a) and (b) above, and I haven't
> > > > > seen any technical problem with it.
> > > > > 
> > > > 
> > > > (A) has implementation implications and those participating in the
> > > > discussion at the time expressed as not being worth the cost.
> > > > I don't believe b was seen as a significant issue either.
> > > > 
> > > > > Do you have any technical concerns with using an annotation as an
> > > > > indirection?
> > > > > 
> > > > 
> > > > The technicsl issue I have with the approaches the same one that was
> > > > raised when debated previously, ie the implementation overhead of
> > > > requiring inline schemas to be available at the top level.
> > > 
> > > Ok.  I'm ok with keeping the inline case as it is.  However, I think
> > > we need to use the new YL-bis, so that we can support the NMDA.
> > 
> > Given that NMDA support is not yet fully defined, we're still in the
> > transition period where support for both NMDA and non-NMDA
> > implementations need to be considered.  Rob presented some options
> > earlier in the thread that I think captures this.
> 
> Again, note that YLbis supports both NMDA and non-NMDA servers.
> 
> Also note that YLbis is just a different read-only monitoring
> structure.  Given an implementation that supports the old YL, it is
> trivial to add support for YLbis (especially compared to the more than
> non-trivial amount of work required to support schema mount...).
> 
> 
> /martin
> 
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-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67