Re: [netmod] References to the "tags" typedef

["Rob Wilton (rwilton)" <[e-mail]>]

Hi Chris, Mahesh,

> -----Original Message-----
> From: Christian Hopps <[e-mail]>
> Sent: 03 October 2019 20:50
> To: Mahesh Jethanandani <[e-mail]>
> Cc: Christian Hopps <[e-mail]>; Rob Wilton (rwilton)
> <[e-mail]>; [e-mail]
> Subject: Re: [netmod] References to the "tags" typedef
> 
> 
> 
> > On Oct 3, 2019, at 2:34 PM, Mahesh Jethanandani
> <[e-mail]> wrote:
> >
> >
> >
> >> On Oct 3, 2019, at 2:37 AM, Rob Wilton (rwilton) <[e-mail]>
> wrote:
> >>
> >> Hi Chris,
> >>
> >> I know that this is late, but ...
> >>
> >> The YANG packages draft (https://tools.ietf.org/html/draft-rwilton-
> netmod-yang-packages-01, but an updated version will be posted soon), is
> currently using the module-tags typedef to allow a package definition to
> contain a list of tags.
> >>
> >> E.g.
> >> module: ietf-yang-package
> >>      +--ro yang-package
> >>         +--ro name                      yang:yang-identifier
> >>         +--ro version                   yang-sem-ver
> >>         +--ro revision-date?            yanglib:revision-identifier
> >>         +--ro location*                 inet:uri
> >>         +--ro description?              string
> >>         +--ro reference?                string
> >>         +--ro previous-version?         yang-sem-ver
> >>         +--ro tag*                      tags:tag
> >>         +--ro referentially-complete?   Boolean
> >>         ...
> >>
> >> This package definition goes into an instance data document, for which
> the schema should just be ietf-yang-package, but by it importing ietf-
> module-tags.yang, it effectively also pulls in the "container module-tags"
> into the schema for the package definition, that I don't think should be
> there.
> >>
> >> If we keep package tags, then I think that there are two ways to fix
> this:
> >>
> >> (1) Split ietf-module-tags into an ietf-module-tags-types.yang and a
> ietf-module-tags.yang.  But it would be very late to do this, and the
> packages draft isn't even a workgroup document at this stage.
> >
> > I know it is late. But what will it take to split the tags-types module
> from the tags module?
> 
> I do not understand why this is important at all. What does "pulls in"
> exactly mean?

To put YANG instance data into a document you need to know what the schema is associated with the instance data.

Ideally, I want the schema for a YANG package instance data document to just be the ro yang-package structure described above (actually now defined using YANG data extension from draft-ietf-netmod-yang-data-ext).

To use the "tags:tag" typedef, ietf-yang-package had an import on "ietf-module-tags" which both defines a tags type and also a "module-tags" container as well.  I want the typedef, but not the container, because I don't want the schema for the package file to be:
      +--ro yang-package  <-- I do want this
      |  +--ro name                      yang:yang-identifier
      |  ...
      +--ro module-tags   <--  I don't want this
         +- ...

There are a few solutions:

1) Split ietf-module-tags into a ietf-module-tags-types.yang that only defines the typedef and the extension, and hence the ietf-module-tags.yang only defines the module-tags container, and ietf-yang-packages.yang can just import ietf-module-tags-types.yang
2) Have ietf-yang-package.yang define its own "tags" type, hence there is no dependency on "ietf-module-tags.yang" at all.
3) Tweak the schema specification for simplified-inline-schema in instance-data documents so that the use of ietf-module-tags.yang module effectively becomes "import-only" rather than "implemented".
4) Don't worry about the fact that the file schema for a YANG package contains more than it should.

I strongly dislike (4) as an option.
But I think that probably either (2) or (3) would be OK as a solution.

Hence, it is probably not necessarily to split ietf-module-tags.yang into two files, because there are other solutions available.  It isn't even clear to me that (1) is necessarily the best solution anyway ...

Thanks,
Rob


> 
> Thanks,
> Chris.
> 
> >
> >>
> >> (2) Have the package draft define its own "package tag" typedef, and
> not have an import reference on module-tags at all.  Probably if we do
> keep package tags, then we should also consider a mechanism by which they
> can be updated on a device equivalently to module tags.
> >>
> >> I'm currently thinking that the second choice might be a better
> approach at this time, but wanted to check whether you or the WG had an
> opinion.
> >>
> >> Thanks,
> >> Rob
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: netmod <[e-mail]> On Behalf Of Christian Hopps
> >>> Sent: 25 September 2019 17:19
> >>> To: [e-mail]
> >>> Subject: Re: [netmod] I-D Action:
> >>> draft-ietf-netmod-module-tags-09.txt
> >>>
> >>> This adds the deprecated non-NMDA state module.
> >>>
> >>> Thanks,
> >>> Chris.
> >>>
> >>>> On Sep 25, 2019, at 12:15 PM, [e-mail] wrote:
> >>>>
> >>>>
> >>>> A New Internet-Draft is available from the on-line Internet-Drafts
> >>> directories.
> >>>> This draft is a work item of the Network Modeling WG of the IETF.
> >>>>
> >>>>      Title           : YANG Module Tags
> >>>>      Authors         : Christian Hopps
> >>>>                        Lou Berger
> >>>>                        Dean Bogdanovic
> >>>> 	Filename        : draft-ietf-netmod-module-tags-09.txt
> >>>> 	Pages           : 18
> >>>> 	Date            : 2019-09-25
> >>>>
> >>>> Abstract:
> >>>> This document provides for the association of tags with YANG modules.
> >>>> The expectation is for such tags to be used to help classify and
> >>>> organize modules.  A method for defining, reading and writing a
> >>>> modules tags is provided.  Tags may be registered and assigned
> >>>> during module definition; assigned by implementations; or
> >>>> dynamically defined and set by users.  This document also provides
> >>>> guidance to future model writers; as such, this document updates
> RFC8407.
> >>>>
> >>>>
> >>>> The IETF datatracker status page for this draft is:
> >>>> https://datatracker.ietf.org/doc/draft-ietf-netmod-module-tags/
> >>>>
> >>>> There are also htmlized versions available at:
> >>>> https://tools.ietf.org/html/draft-ietf-netmod-module-tags-09
> >>>> https://datatracker.ietf.org/doc/html/draft-ietf-netmod-module-tags
> >>>> -09
> >>>>
> >>>> A diff from the previous version is available at:
> >>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-netmod-module-tags-09
> >>>>
> >>>>
> >>>> Please note that it may take a couple of minutes from the time of
> >>>> submission until the htmlized version and diff are available at
> >>> tools.ietf.org.
> >>>>
> >>>> Internet-Drafts are also available by anonymous FTP at:
> >>>> ftp://ftp.ietf.org/internet-drafts/
> >>>>
> >>>> _______________________________________________
> >>>> netmod mailing list
> >>>> [e-mail]
> >>>> https://www.ietf.org/mailman/listinfo/netmod
> >>>>
> >>
> >> _______________________________________________
> >> netmod mailing list
> >> [e-mail]
> >> https://www.ietf.org/mailman/listinfo/netmod
> >
> > Mahesh Jethanandani
> > [e-mail]