Re: [netmod] Datastore leaf for yang instance data

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 28 November 2018 15:32 UTC

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Date: Wed, 28 Nov 2018 16:32:15 +0100
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Robert Wilton <rwilton@cisco.com>
CC: Balázs Lengyel <balazs.lengyel@ericsson.com>, Ladislav Lhotka <lhotka@nic.cz>, Martin Bjorklund <mbj@tail-f.com>, "netmod@ietf.org" <netmod@ietf.org>
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Subject: Re: [netmod] Datastore leaf for yang instance data
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On Wed, Nov 28, 2018 at 03:27:26PM +0000, Robert Wilton wrote:
> 
> On 28/11/2018 10:20, Juergen Schoenwaelder wrote:
> > On Wed, Nov 28, 2018 at 09:41:12AM +0000, Balázs Lengyel wrote:
> > > > I do not buy this story. Your software needs to decide somehow what
> > > > instance data means. A config true leaf in candidate means something
> > > > different than the same config true leaf in running and this yet again
> > > > means something different than the same config true leaf in operational.
> > > > 
> > > > /js
> > > BALAZS: As I understood the WG decided that this draft should only be about
> > > the format of the yang instance data. What the SW does with it is out of
> > > scope. So considerations whether instance data should be loaded into running
> > > or candidate or not at all, are outside the scope.
> > If you do not know what the instance data means, any attempt to use it
> > is kind of broken.
> > > I want to provide a datastore indicator, but how that should be used (and
> > > thus what is exactly means) is out of scope.
> > I disagree. The datastore indicator is needed to understand what the
> > data means, i.e., to do anything meaningful with it.
> 
> I think that a datastore indicator is useful sometimes.  E.g. it might be
> helpful in some cases to know that the data was associated with a particular
> datastore.
> 
> But in the general case I think that this is just "data at rest", and
> probably the key thing to know is whether (i) the data relates to
> configuration, or (ii) the data relates to operational state.
> 
> This could potentially be inferred from a datastore leaf, or perhaps this
> distinction could more explicitly be made by a separate field, which I would
> make an enumeration or identity, since there might be other types of data in
> future, such as capability information or diagnostics.
>

I do not understand why a datastore leaf is not sufficient and why we
need yet something new. If ever needed, NMDA does allow us to define
new datastores.

/js

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