Re: [netmod] [Netconf] Alternative YANG library structure for 7895bis

[Martin Bjorklund <[e-mail]>]

Vladimir Vassilev <[e-mail]> wrote:
> On 12/12/2017 08:20 PM, Martin Bjorklund wrote:
> 
> > Hi,
> >
> > Vladimir Vassilev <[e-mail]> wrote:
> >>
> >> On 12/08/2017 04:06 PM, Juergen Schoenwaelder wrote:
> >>> On Fri, Dec 08, 2017 at 04:03:06PM +0100, Martin Bjorklund wrote:
> >>>> Vladimir Vassilev <[e-mail]> wrote:
> >>>>> On 11/15/2017 06:29 PM, Robert Wilton wrote:
> >>>>>
> >>>>>> I don't think that this is really a good idea.  You would end up
> >>>>>> returning server metadata in addition to the configuration.
> >>>>> Obviously RFC 7895 defines only config false; data and I was not
> >>>>> proposing a change to that. But I agree something has to be added to
> >>>>> complete the solution. Special purpose datastore identities can be
> >>>>> defined that return instance of yang-library data when read with
> >>>>> <get-data>. (Datastores with yang-library config false; only data not
> >>>>> represented in 'operational')
> >>>>>
> >>>>> Adding this special yang-library-datastore to the proposed
> >>>>> ietf-datastores container e.g.
> >>>>>
> >>>>> module: ietf-datastores
> >>>>> +--ro datastores
> >>>>> |  +--ro datastore* [name]
> >>>>> |     +--ro name          identityref
> >>>>> |     +--ro yang-library-datastore          identityref
> >>>>>
> >>>> I don't understand this proposal.  How would a client learn the
> >>>> library for <running>?  For <operational>?
> >>> My interpretation is that the client reads the datastores list from
> >>> <operational> and the list entries give you the identity of a separate
> >>> datastore that gives you the content of the yang library for that
> >>> datastore. (For each datastore, you have a separate datastore to
> >>> report its yang library.)
> >> Yes. The default value for yang-library-datastore leaf is
> >> ds:operational (the only possible one for the ds:operational
> >> datastore). This is backward compatible. If one needs different model
> >> for 'running', etc. then a new datastore identity has to be defined
> >> and set in place of the default value. Then this identity can be used
> >> to read the yang-library data with <get-data>.
> > Ah, ok.  This is a clever solution, but quite complicated.  It
> > requires several round trips for a client to learn all library
> > instances.  Also, w/o any changes, it is not clear which module-set-id
> > is sent in the capability, and a client must query all module-set-ids
> > in all (meta)datastores in order to just check if it has the latest
> > version or not.  It is also not clear how the existing notification
> > "yang-library-change" would work when there are multiple instances
> > involved.
> How about this?
> module: ietf-datastores
> ...
>   augment /yanglib:yang-library-change:
>     +---- datastore?   identityref

This has the same issue as augementing a datastore leaf-list into the
current /modules-state/modules list would have - old clients won't
understand this new node.


/martin