Re: [netmod] 答复: 答复: Please clarify implementation about ‘when’

Ladislav Lhotka <lhotka@nic.cz> Thu, 26 September 2019 10:27 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
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Date: Thu, 26 Sep 2019 12:27:17 +0200
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On Thu, 2019-09-26 at 09:39 +0000, Schönwälder, Jürgen wrote:
> On Thu, Sep 26, 2019 at 09:45:26AM +0200, Martin Bjorklund wrote:
> > > > >    o  There MUST be no nodes tagged with "when" present if the "when"
> > > > >       condition evaluates to "false" in the data tree.
> > > > 
> > > > It also says in 8.2:
> > > > 
> > > >    o  If a request modifies a configuration data node such that any
> > > >       node's "when" expression becomes false, then the node in the data
> > > >       tree with the "when" expression is deleted by the server.
> > > 
> > > Right. But the request won't modify a configuration data node because it
> > > is
> > > rejected. So the premise of the above implication doesn't hold, and the
> > > conclusion doesn't apply.
> > 
> > With the same logic you can claim conformance if you reject a request
> > to create nodes under a case if another case is active.  I think it is
> > quite clear that this auto-deletion is part of the spec, and something
> > clients can rely on.  If the intention had been that this was optional
> > to implement, it would have been clearly stated, and there would have
> > been mechanism present for clients to detect this.
> > 
> 
> Yes, this auto-delete behaviour is part of the specification and it
> was not an oversight that this slipped in.

Of course I know it was the intention, even though I have been against it all
the time.

> 
> Sure, one can discuss whether this feature is useful or harmful
> but the only way to officially remove this is to create a new
> specification and to run it through the IETF process.

I do insist that the wording in 7950 permits my interpretation, so I don't
propose any change.

What I propose instead is to remove such protocol-specific parts from the
specification of the YANG language, and clarify it in the specification of
individual protocols.

Lada

> 
> /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/>
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67