Re: [netmod] [Netconf] What should a server response be? - depending on NP-containers

[Juergen Schoenwaelder <[e-mail]>]

On Tue, Aug 23, 2016 at 10:10:12AM +0200, Vladimir Vassilev wrote:
> On 08/23/2016 09:33 AM, Juergen Schoenwaelder wrote:
> > On Tue, Aug 23, 2016 at 08:42:34AM +0200, Vladimir Vassilev wrote:
> > > On 08/23/2016 12:08 AM, Alex Campbell wrote:
> > > > The intention in this case is obviously to evaluate the 'must' statement if
> > > > the container contains any values; what would break if we said that
> > > > 
> > > >      A non-presence container exists in the data tree if and only if it has
> > > >      any children which exist in the data tree.
> > > > 
> > > > thus disallowing the existence of empty NP-containers in the data tree?
> > > The question is where is the misunderstanding.
> > > 
> > >     "If a node that exists in the accessible tree has a non-presence
> > >     container as a child, then the non-presence container also exists in
> > >     the tree."
> > > 
> > > What does this mean? I believe there is confusion based on "the tree"
> > > refering not to the data tree but the Xpath context. At least I hoped until
> > > I realized the text was introduced as a solution to Y41 'clarification of
> > > "must" in NP-container'. That definitely means it addresses the must
> > > statements in the non-presence containers and it means "the tree" as in the
> > > data tree.
> > My reading is that 'tree' refers to the 'accessible tree' used earlier
> > in the sentence. The accessible tree itself is defined just above the
> > quoted sentence. If my reading of the text is correct, then the
> > obvious clarification would be:
> > 
> > OLD
> > 
> >     If a node that exists in the accessible tree has a non-presence
> >     container as a child, then the non-presence container also exists in
> >     the tree.
> > 
> > NEW
> > 
> >     If a node that exists in the accessible tree has a non-presence
> >     container as a child, then the non-presence container also exists in
> >     the accessible tree.
> > 
> > /js
> > 
> So should the must statements defined in the non-presence container which is
> now part of the accessible tree be evaluated or not?
>

I think we need to carefully dissect things in order to make
progress. The above text is about XPATH contexts and accessible
trees. It is not about what needs to be checked during
validation. This is defined in section 8 and in particular section
8.1.

   The following properties are true in a valid data tree:

   o  All "must" constraints MUST evaluate to "true".

This clearly talks about the data tree. The resolution of issue 42
says:

   2014-07-21 meeting proposal: Clarify that for validation purposes,
   NP containers always exist.

Putting these pieces together, it seems to me that for the purpose of
validation, an NP container is assumed to always exist in the data
tree and its MUST statement is evaluated.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <http://www.jacobs-university.de/>