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

[Ladislav Lhotka <[e-mail]>]

> On 23 Aug 2016, at 10:25, Juergen Schoenwaelder <[e-mail]> wrote:
> 
> 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.

But only if the closest ancestor that is not an NP-container exists, or there is no such ancestor.

Lada

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