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

> On 23 Aug 2016, at 11:09, Martin Bjorklund <mbj@tail-f.com> wrote:
> 
> Vladimir Vassilev <vladimir@transpacket.com> wrote:
>> On 08/23/2016 10:15 AM, Martin Bjorklund wrote:
>>> They are evaluated.  See Section 7.5.3:
>>> 
>>>    When a datastore is validated, all "must" constraints are
>>>    conceptually evaluated once for each node in the accessible tree (see
>>>    Section 6.4.1).
>>> 
>>> 
>>> /martin
>> Then we have the case I objected to and the example:
>> 
>> YANG 1.0:
>> 
>> augment "/if:interfaces/if:interface" {
>>    container inet {
>>        must "../name = 'me0'" {
> 
> This should have been a 'when' expression, not 'must'.  Alternatively,

An interesting case would be if there is the "when" statement as you suggest, and then also one or more "must" statements. IMO, in this case the "when" statement needs to be evaluated first using the procedure of sec. 7.21.5, and if (and only if) the result is true, then the "must" statements are evaluated. Again, an NP-container is no different from a leaf with a default value.

Lada

> it should have been a P-container, since obviously the container has
> some semantics.  Or alternatively, the must expression should have
> been on the address leaf, since this is what you really checked.
> 
> 
> 
> /martin
> 
> 
>>            description
>>                 "The inet container is only valid for the management ('me0')
>>                 interface.";
>>        }
>>        leaf address {
>>            type inet:ip-prefix;
>>        }
>>    }
>> }
>> 
>> YANG 1.1 (replace "../name = 'me0'" with "../name='me0' or not
>> (./address)" and process 95 unnecessary Xpath evaluations).
>> 
>> I think this proves the argument that there will be more unnecessary
>> Xpath processing.  In addition it illustrates how a simple task
>> requires ugly patch (the ".. or not (./address)" added to the must
>> expression) just to ensure the expression does not fail in the default
>> case where the interface is not named "me0" and the user has not even
>> attempted to create empty /interfaces/interface/inet container in YANG
>> 1.1.
>> 
>> Vladimir
>> 
> 
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