Re: [netmod] Y60 - coexistence with YANG 1.0

[Ladislav Lhotka <[e-mail]>]

Ladislav Lhotka <[e-mail]> writes:

>> On 10 Sep 2015, at 12:55, Martin Bjorklund <[e-mail]> wrote:
>> 
>> Hi,
>> 
>> I think we agreed that is ok for a YANG 1.1 module to import a YANG
>> 1.0 module.
>> 
>> But should it also be ok for a 1.0 module to import a 1.1 module?
>
> I think it should be illegal for a 1.0 module to import with revision if the requested revision is 1.1.
>
>> 
>> If we make this illegal, we might run into problems.  For example,
>> ietf-ip imports ietf-interfaces.  Suppose we update ietf-interfaces
>> and the new version use YANG 1.1.  Is it ok for a server to implement
>> the 1.0 version of ietf-ip and 1.1 version of ietf-interfaces?  If the
>> answer is no, it means that we either have to update all modules to
>> 1.1 more or less at the same time (including vendor models!), or we
>> keep existing modules on 1.0 "forever".
>> 
>> At the lastest interim, it was suggested that a server that implements
>> such a combination of models would internally promote the 1.0 module
>> to 1.1, and thus make this combination legal.
>
> I think we need a way for the server to identify itself to the client as 1.1-capable, and then:
>
> - 1.1-capable server: if 1.0 module X imports Y *without revision*,
> and the revision of Y advertised by the server (with
> default-revision=true), then module X is automatically interpreted as
> 1.1.

Correction:

- 1.1-capable server: if 1.0 module X imports Y *without revision*, and
  the revision of Y advertised by the server (with
  default-revision=true) is 1.1, then module X is automatically
  interpreted as 1.1.

Lada

>
> - 1.0-only server: if 1.0 module X import Y without revision, then the latest 1.0 revision of Y is used. If 1.1 revisions exist, they are not used.
>
>> 
>> Such a strategy should also be safe for old clients, still treating
>> the module as being 1.0.
>
> I am not sure about this, I think a 1.0-only client cannot work with a 1.1-capable server is some 1.1 additions are used (e.g. if-feature expressions).
>
>> 
>> It is a bit unclear what the server should do if the 1.0 module that
>> it "internally promotes" to 1.1 contains something that is illegal in
>> 1.1, e.g.:
>> 
>>        default "a\xb”;
>
> We should write an erratum to 6020 making this illegal in 1.0, too.
>
> Lada
>
>> 
>> Comments?
>> 
>> 
>> /martin
>> 
>> _______________________________________________
>> netmod mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/netmod
>
> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: E74E8C0C
>
>
>
>
> _______________________________________________
> netmod mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/netmod

-- 
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C