Re: [netmod] evaluation of "when" under NMDA

[Ladislav Lhotka <[e-mail]>]

On Mon, 2017-12-04 at 17:34 +0100, Martin Bjorklund wrote:
> Ladislav Lhotka <[e-mail]> wrote:
> > Hi,
> > 
> > if we have
> > 
> > augment "/target/node" {
> >   when "...";
> >   ...
> > }
> > 
> > is the "when" expression supposed to be evaluated separately in each
> 
> datastore,
> > and the augment applied only in those datastores where the result is true?
> 
> Yes.

But then it cannot be guaranteed that the schema for <operational> is a superset
of the schema of configuration datastores - the when expression can evaluate to
false in <operational> but true in <intended>.

Lada

> 
> > RFC 7950 says in sec. 7.21.5 that the context node for XPath evaluation is
> 
> "the
> > augment's target node in the data tree", but with NMDA we have multiple data
> > trees, hence multiple target nodes.
> 
> We had multiple datastores even before NMDA.  The when expression
> could be true in candidate but false in running.
> 
> /martin
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67