Hi Martin,
> -----Original Message-----
> From: Martin Bjorklund <[email protected]>
> Sent: 07 October 2019 09:00
> To: Rob Wilton (rwilton) <[email protected]>
> Cc: [email protected]; [email protected];
> [email protected]
> Subject: Re: [netmod] References to the "tags" typedef
>
> "Rob Wilton (rwilton)" <[email protected]> wrote:
> > [Copying Balazs because this discussion is moving to instance-data
> > document schema definitions.]
> >
> > > -----Original Message-----
> > > From: Schönwälder, Jürgen <[email protected]>
> > > Sent: 04 October 2019 10:36
> > > To: Rob Wilton (rwilton) <[email protected]>
> > > Cc: Christian Hopps <[email protected]>; Mahesh Jethanandani
> > > <[email protected]>; [email protected]
> > > Subject: Re: [netmod] References to the "tags" typedef
> > >
> > > On Fri, Oct 04, 2019 at 08:17:33AM +0000, Rob Wilton (rwilton) wrote:
> > > >
> > > > 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
> > > > +- ...
> > > >
> > >
> > > Isn't import-only-module in YANG library take care of this?
> > [RW]
> > Yes, that is one solution.
> >
> > The instance data document (probably in JSON, but I've given an XML
> > snippet below) could use the "inline-spec" for specifying the schema.
> >
> > But this means that every package instance file, needs to have some
> > boilerplate like this before the actual package definition.:
> >
> > <?xml version="1.0" encoding="UTF-8"?> <instance-data-set xmlns=
> > "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
> > <name>some-yang-package</name>
> > <inline-spec>[email protected]</inline-spec>
> > <inline-content-schema>
> > <yang-library xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
> > <module-set>
> > <name>all</name>
> > <module>
> > <name>ietf-yang-package</name>
> > <revision>2019-09-11</revision>
> > </module>
> > <import-only-module>
> > <name>ietf-yang-package-types</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <import-only-module>
> > <name>ietf-module-tags</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <import-only-module>
> > <name>ietf-yang-revisions</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <module>
> > <name>ietf-yang-structure-ext</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <module>
> > <name>ietf-yang-types</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <module>
> > <name>ietf-yang-library</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > <module>
> > <name>ietf-inet-types</name>
> > <revision>xxxx-xx-xx</revision>
> > </module>
> > </module-set>
> > </yang-library>
> > </inline-content-schema>
> > <content-data>
> > // Actual package information goes here.
> > </content-data>
> > </instance-data-set>
> >
> > https://datatracker.ietf.org/doc/draft-ietf-netmod-yang-instance-file-
> > format/?include_text=1
> >
> > The YANG instance data draft provides some other choices:
> > (1) (External Method) Don't define the schema, just assume that
> > clients know what it will be for YANG packages. E.g. it would be
> > specified in the YANG packages RFC.
>
> I prefer this solution for the packages document.
The risk here, is that the package definition may get extended/augmented over
time.
>
> > (2) (URI method) Put the schema in a separate instance data document
> > and reference that. This could be defined in the YANG packages RFC,
> > but it might open the question of what URI can you use to retrieve it.
> > (3) Simplified inline schema.
> >
> > It is the third one that I would ideally like to use.
>
> Ugh, I haven't paid enough attention to the instance data document... I
> will comment on this design in a separate email.
OK 😊
There is also a 4th choice here.
My plan is that the latest version of the packaging draft will augment the
instance-data-set structure to allow a named package to be used as a
specification for a schema.
So, package definitions could make use of this. It would be still be concise,
but complete and extensible.
>
> > Here, the package data would like something like this (sorry, in JSON
> > this time):
> >
> > "ietf-yang-instance-data:instance-data-set": {
> > "name": "example-ietf-network-device-pkg",
> > "module": [ "[email protected]" ],
> > "description": "YANG package definition",
> > "content-data": {
> > "ietf-yang-package:yang-package": {
> > "name": "example-ietf-network-device-pkg",
> > // Actual package information goes here.
> > }
> > }
> > }
> >
> > Here, the schema is defined by the "module" line
> > "[email protected]". I think that there are some
> > details to work out, but I think that the import dependencies for
> > "ietf-yang-package.yang" could be automatically resolved as
> > import-only YANG modules. I have also tried to minimize the required
> > imports (e.g. don't import YANG library, perhaps don't import from
> > module-tags).
>
> You shouldn't have to do that. You should use the appriopriate types.
The packages import against YANG library was only pulling in the "grouping
location-leaf-list", so for YANG library, having the import doesn't seem to be
that helpful.
>
> > In terms of typedefs, are two typedefs equivalent if they have exactly
> > the same definition in two different modules? Or does the fact that
> > they are named given them a slightly different meaning?
>
> By reusing appriopriate typedefs you get clearer semantics. In the
> extreme case everyting is just strings with some descripton statements
> (you might think that this is absurd, but this approach has been taken by
> some data model designers (not necessarily yang) ...)
Yes, I agree with you in principle, in that referencing the typedef provides
more semantic information that just mirroring the type.
Thanks,
Rob
>
>
> /martin
>
> >
> > Thanks,
> > Rob
> >
> >
> > >
> > > /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/>
> >
> > _______________________________________________
> > netmod mailing list
> > [email protected]
> > https://www.ietf.org/mailman/listinfo/netmod
> >
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