Re: [netmod] Does defining a feature require the module be implemented?

Hi Andy,

Thanks for your response, but I'm having trouble parsing it.  At first I thought it was just me, but I asked someone else and they said the same.  Can you state either:

	1) a module MUST be implemented in order for its features to be defined.
	2) feature-defintion and module-implementation are orthogonal.

Is there a normative definition you can point to, or are we working backwards from YANG Library (but note that the two versions of YANG Library enabled it differently).

Thanks,
Kent

> On May 13, 2022, at 12:04 PM, Andy Bierman <andy@yumaworks.com> wrote:
> 
> 
> 
> On Fri, May 13, 2022 at 8:49 AM Robert Varga <nite@hq.sk <mailto:nite@hq.sk>> wrote:
> On 13/05/2022 17:03, Kent Watsen wrote:
> > True, the current YANG Library structure allows features to be declared 
> > only for implemented modules, but I'm unsure how intentional that was.
> > 
> > We always talk about how a module needs to be "implemented" in order for 
> > its Identities to be defined, but we don't ever talk about the same 
> > being true for Features.
> > 
> > It seems that, if this is the case, there should be a note somewhere 
> > about features used in "grouping" statements and hence the 
> > exporting-module must be "implemented" for the grouping to be used as 
> > intended.
> > 
> > These sections from RFC 8407 don't say anything about it:
> > 
> >   * 4.13. Reusable Groupings
> >     <https://datatracker.ietf.org/doc/html/rfc8407#section-4.13 <https://datatracker.ietf.org/doc/html/rfc8407#section-4.13>>
> >   * 4.17.  Feature Definitions
> >     <https://datatracker.ietf.org/doc/html/rfc8407#section-4.17 <https://datatracker.ietf.org/doc/html/rfc8407#section-4.17>>
> 
> Right, I think we need to first clarify what RFC8525's:
> 
> >            "An entry in this list indicates that the server imports
> >             reusable definitions from the specified revision of the
> >             module but does not implement any protocol-accessible
> >             objects from this revision.
> 
> "reusable definition" seems to be an under-defined term. I think the 
> intent is to cover not only groupings, but also typedefs and extensions.
> 
> 
> 
> I thought this issue was obvious and already settled with the iana-crypt-hash module.
> There are features related to the server implementation of data nodes
> that use the crypt-hash typedef.
> 
> We list iana-crypt-hash (or any module that has features) in the implemented modules.
> The client needs to know this info and that is the only way to do it.
> 
> I think these should also include identities and features -- but that 
> opens up quite a can of worms in terms of what a 'supported feature' is:
> - is it tied to a particular revision or does it apply to all revisions?
> - is it a property of imported or (ultimante) importing module?
> 
> Regards,
> Robert
> 
> Andy
>  
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