Re: [netmod] yang-08: changing a default

[Martin Bjorklund <mbj at tail-f.com>]

Andy Bierman <andy at netconfcentral.com> wrote:
> SMIv2-like CLRs to preserve backward compatibility don't
> work very well in YANG.

That's exactly what Section 10 "Updating a module" specifies.  Are you
suggesting we remove that section?

I think these rules work (and FWIW, at our company we have some
implementation experience from using them).

> IMO, a better implementation
> strategy for the client is to construct the server's
> view of the schema tree from the <hello> and avoid any
> heuristics based on the CLRs in Sec. 10.  If the client
> supports deviations, then the change-control rules are
> totally irrelevant, since deviations don't follow any rules.
> 
> (It would help if revisions were mandatory to use.
> The CLRs do not help at all for revision-less modules.
> Nothing does.)

I think it would be ok to change the SHOULD in section 10 to MUST:

OLD:

  For any published change, a new "revision" statement (^revision^)
  SHOULD be included

NEW:

  For any published change, a new "revision" statement (^revision^)
  MUST be included

>   d. require revision on all modules and submodules, and think about
>      import-by-revision very carefully. The WG should understand how it will
>      function within the IETF wrt/ all processes.  After there are specific
>      recommendations for module reuse practices, then rules for
>      import-by-revision
>      may be appropriate.

I think text about import / include by revision should go into the
usage guidelines document.  At least some text that says "think
carefully about it!", preferably with some guidelines on what impact
an import-by revision has. 



/martin