Re: [netmod] Augmentation to Groupings

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Tue, 19 December 2017 20:16 UTC

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Date: Tue, 19 Dec 2017 21:16:47 +0100
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Alexander Clemm <alexander.clemm@huawei.com>
Cc: Xufeng Liu <xufeng.liu.ietf@gmail.com>, NETMOD WG <netmod@ietf.org>
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Subject: Re: [netmod] Augmentation to Groupings
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The question is not why we have groupings, the question is why
augmentations are restricted to schema node identifiers. I provided an
answer for the later, namely explicit control of augmentation effects.

It is of course OK to disagree with the design. I am just trying to
explain that this was an explicit design decision when YANG was
designed.

/js

On Tue, Dec 19, 2017 at 07:51:05PM +0000, Alexander Clemm wrote:
> IMHO it would be worth a try.  If you wanted to only augment _some_ uses of a grouping, you could still do the same as today.  Also, I would expect augmentations to only affect servers that support the module defining the augmentation.  If verbosity were not an issue, why were groupings introduced in the first place?
> --- Alex
> 
> > -----Original Message-----
> > From: netmod [mailto:netmod-bounces@ietf.org] On Behalf Of Juergen
> > Schoenwaelder
> > Sent: Tuesday, December 19, 2017 11:15 AM
> > To: Xufeng Liu <xufeng.liu.ietf@gmail.com>
> > Cc: NETMOD WG <netmod@ietf.org>
> > Subject: Re: [netmod] Augmentation to Groupings
> > 
> > The current approach may be verbose but it protects users of groupings from
> > unwanted and uncontrolled side effects. Augmenting a grouping as
> > suggested affects _all_ uses of a grouping; this can be tricky in situations
> > where groupings are widely used.
> > 
> > /js
> > 
> > On Tue, Dec 19, 2017 at 11:45:06AM -0500, Xufeng Liu wrote:
> > > During the discussions of TE tunnel and topology models, we have found
> > > that it is desirable to have the capability of augmenting a grouping.
> > >
> > > In our case, there are multiple technology specific models augmenting
> > > a base generic model. In the base model, some groupings are used
> > > multiple times, and each augmentation model needs to add more schema
> > > nodes to the grouping structure. For now, we have to specify an
> > > “augment” statement for each location where the grouping is used. Such
> > > an “augment” statement is repeated many times. It would be convenient
> > > and cleaner if we could augment the grouping.
> > >
> > > We’d like to hear opinions on the feasibility of such a capability.
> > >
> > > Thanks,
> > >
> > > - Xufeng
> > 
> > > _______________________________________________
> > > netmod mailing list
> > > netmod@ietf.org
> > > https://www.ietf.org/mailman/listinfo/netmod
> > 
> > 
> > --
> > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> > Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> > Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>
> > 
> > _______________________________________________
> > netmod mailing list
> > netmod@ietf.org
> > https://www.ietf.org/mailman/listinfo/netmod

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>