Re: [yang-doctors] Review of draft-wu-l3sm-rfc8049bis?

[Juergen Schoenwaelder <[e-mail]>]

Adrian,

I do not understand the details why RFC 8049 is fundamentally
broken. The abstract of the ID says:

   If approved, this document obsoletes RFC 8049.  The changes are a
   series of small fixes to the YANG module, and some clarifications to
   the text.

This does not read like fundamentally flawed and not implementable.
That said, I did react to Jan's statement that kind of indicated that
these changes are generally OK - which I think they are not.

If this document chooses to not follow the YANG update rules, I think
this should be supported by a clear documentation why this is
considered to be OK, somewhere in the document.

/js

On Thu, Oct 05, 2017 at 03:41:28PM +0100, Adrian Farrel wrote:
> Pardon me for asking for some help getting this straight in my head.
> 
> When we move from one version of an I-D to another, we don't pay any attention
> to backward compatibility.
> 
> When we revise an established module we must be backward compatible to allow the
> new version to be inserted without damaging existing implementations, or we must
> call the module something new to avoid confusion.
> 
> When we have a module that cannot be implemented (because it is broken) and that
> is being fixed through the obsoleting of an RFC, do we *really* care about
> backward compatibility? If we do care, then the answer is simple: we revise the
> module name, etc. If the issue isn't a big deal, we go ahead as written.
> 
> Thanks,
> Adrian
> 
> > -----Original Message-----
> > From: Juergen Schoenwaelder [mailto:[e-mail]]
> > Sent: 05 October 2017 15:07
> > To: Jan Lindblad
> > Cc: Lou Berger; YANG Doctors; [e-mail]
> > Subject: Re: [yang-doctors] Review of draft-wu-l3sm-rfc8049bis?
> > 
> > On Thu, Oct 05, 2017 at 03:44:24PM +0200, Jan Lindblad wrote:
> > > Lou,
> > >
> > > > What about the type changes (int32->int64,
> > >
> > > This is a backwards compatible change according to both 6020 and 7950.
> > >
> > > > int->string)?
> > >
> > > Even if a type change int->str might qualify as "backwards compatible"
> > according to 6020 and 7950, the particular change at hand is not because of
> > considerable changes in semantics.
> > 
> > I think both type changes are problematic. RFC 7950 says:
> > 
> >    o  A "type" statement may be replaced with another "type" statement
> >       that does not change the syntax or semantics of the type.  For
> >       example, an inline type definition may be replaced with a typedef,
> >       but an int8 type cannot be replaced by an int16, since the syntax
> >       would change.
> > 
> > /js
> > 
> > >
> > > /jan
> > >
> > >
> > > > On 10/5/2017 9:27 AM, Jan Lindblad wrote:
> > > >> Lou,
> > > >>
> > > >> I have reviewed the updated model from a YANG perspective. The old
> > model contained syntax errors(!), so there was no way to (correctly) implement
> > it. Hence I believe requirements on backwards compatibility should be treated
> > lightly.
> > > >>
> > > >> /jan
> > > >>
> > > >>
> > > >>
> > > >>> Hi,
> > > >>>
> > > >>>    Has there been a review conducted or is there one planned for
> > > >>> draft-wu-l3sm-rfc8049bis?  If not, I think one is needed.  I'm looking
> > > >>> at it now as part of RtgDir review and I believe some non-backwards
> > > >>> compatible changes in the defined yang module.
> > > >>>
> > > >>> Thanks,
> > > >>> Lou
> > > >>>
> > > >>> PS for module diffs see:
> > > >>>
> > > >>> https://tools.ietf.org/rfcdiff?difftype=--hwdiff&url2=draft-wu-l3sm-
> > rfc8049bis-05.txt&url1=rfc8049
> > > >>>
> > > >>> _______________________________________________
> > > >>> yang-doctors mailing list
> > > >>> [e-mail]
> > > >>> https://www.ietf.org/mailman/listinfo/yang-doctors
> > > >>
> > > >
> > >
> > > _______________________________________________
> > > yang-doctors mailing list
> > > [e-mail]
> > > https://www.ietf.org/mailman/listinfo/yang-doctors
> > 
> > --
> > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> > Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
> > Fax:   [phone]         <http://www.jacobs-university.de/>
> 

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <http://www.jacobs-university.de/>