Re: [netmod] [Anima] mcr's YANG question raised during the ANIMA WG session

["Fries, Steffen" <[e-mail]>]

Hi Jan,

Thank you for the help. Based on your example I crafted another version of the BRSKI-PRM voucher request with a grouping containing only the additional 3 fields needed in BRSKI-PRM, which is then used to augment the original voucher. 

We have to do some further testing to see if it works out.

Best regards
Steffen

> -----Original Message-----
> From: Anima <[e-mail]> On Behalf Of Jan Lindblad
> Sent: Freitag, 5. August 2022 10:41
> To: Michael Richardson <[e-mail]>
> Cc: [e-mail]; [e-mail]
> Subject: Re: [Anima] [netmod] mcr's YANG question raised during the ANIMA
> WG session
> 
> Michael,
> 
> Comments inline.
> 
> > On 5 Aug 2022, at 01:01, Michael Richardson <[e-mail]> wrote:
> >
> > Thank you for very much for the reply.
> >
> > Jan Lindblad <[e-mail]> wrote:
> >> I had a look at your test example. The example is invalid, but pyang
> >> fails to detect the error and overwrites some internal structures,
> >> with the result below. The root cause of the problem is this:
> >
> > ...
> >
> >> Each one of the two uses statement brings in a "container voucher"
> >> (with partly different content) at this point in the schema. That is
> >> an attempt at a duplicate definition of voucher, which is an error.
> >
> > okay, so it partly works, which is an error, and I'll see if I can
> > make that into a test case for pyang.
> 
> Very good.
> 
> > BUT:
> >   The goal is exactly to be able to combine two extensions to RFC8366 into a
> >   new module that has both extensions.  Is there another way to do this?
> >
> > Puting them into two containers does not accomplish the goal, because
> > now you have two expires-on, ...
> 
> Of course. I just added the containers to show that pyang could understand the
> modules once the modeling error was removed. Just to clarify what was going
> on.
> 
> >> Pyang
> >> misses this, and overwrites one voucher object with the next, losing
> >> some of the content.
> >
> >> By placing the two uses statements into separate containers, pyang is
> >> able to successfully make a tree:
> >
> > ...
> >
> >> Normally in YANG, it wouldn't be hard to to let modules "B" and "C"
> >> augment module "A" independently. But here you are working with
> >> groupings in such a way that both "B" and "C" build up a complete
> >> grouping with everything in "A". When "D" tries to use both "B" and
> >> "C", there is inevitably unwanted duplication.
> >
> >> If instead, "B" and "C"
> >> just defined their little contributions, "D" could import groupings
> >> from "A", "B" and "C" and compose them as desired.
> >
> > The reason I am asking this question now, and proposing this example
> > now, is so that if there is a better way to build "B" and "C" then we
> > need to know about that *now*
> >
> > I see that you have proposed a different way, which I will attempt to
> > work through.  Fortunately, we still have time to fix some things.
> 
> Feel free to reach out offline for discussion and review.
> 
> Best Regards,
> /jan
> 
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