Re: [netmod] 'when' statement in edit-config payload parsing

> On 12 Sep 2016, at 15:33, Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> wrote:
> 
> Hi,
> 
> I think Section 8.3.3. provides an answer:
> 
>   When datastore processing is complete, the final contents MUST obey
>   all validation constraints.  This validation processing is performed
>   at differing times according to the datastore.  If the datastore is
>   <running/> or <startup/>, these constraints MUST be enforced at the
>   end of the <edit-config> or <copy-config> operation.  If the
>   datastore is <candidate/>, the constraint enforcement is delayed
>   until a <commit> or <validate> operation.

But sec. 8.1 lists "when" conditions among properties that must be true in all data trees, so it can never be false in <candidate/> either.

My answer to Yves' question is that the edit-config has to be applied atomically, and the constraints verified of the final result (a tentative version of "running") in which A is already present, so the edit is accepted.

Note, however, that the "when" expression should be

    when "../A";

The one in the "dummy" module is always false.

Lada

> 
> /js
> 
> On Mon, Sep 12, 2016 at 01:27:52PM +0200, Yves Beauville wrote:
>> Hi,
>> 
>> I am trying to interpret this statement in Section 8.3.1 Payload Parsing of
>> RFC 6020.
>> 
>>   o  If data for a node tagged with "when" is present, and the "when"
>> condition evaluates to "false", the server MUST reply with an
>> "unknown-element" error-tag in the rpc-error.
>> 
>> With the context node defined Section 7.19.5. The when Statement
>> 
>>   o  If the context node represents configuration, the tree is the data in
>> the NETCONF datastore where the context node exists. The XPath root node has
>> all top-level configuration data nodes in all modules as children.
>> 
>> I am providing this dummy module to illustrate my question:
>> 
>> module dummy {
>>  namespace "http://dummy.com";
>>  prefix "du";
>> 
>>  container root {
>>    leaf A {
>>      type empty:
>>    }
>>    leaf B {
>>      when "A";
>>      type uint32;
>>    }
>>  }
>> }
>> 
>> And I consider the following <edit-config> request, while A & B do not exist
>> yet in the current datastore.
>> 
>>     <rpc message-id="101"
>>          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
>>       <edit-config>
>>         <target>
>>           <running/>
>>         </target>
>>         <config>
>>           <root xmlns="http://dummy.com">
>>             <A/>
>>             <B>
>>               3
>>             </B>
>>           </dummy>
>>         </config>
>>       </edit-config>
>>     </rpc>
>> 
>> During the parsing of the payload of the <edit-config>, leaf "A" is not yet
>> present in the running datastore. The "when" statement that controls "B"
>> evaluates to false.
>> 
>> Does this mean that the above edit-config request should be rejected with an
>> "unknown-element" error-tag in the rpc-error? Or am I misinterpreting the
>> RFC?
>> 
>> Yves
> 
>> _______________________________________________
>> netmod mailing list
>> netmod@ietf.org
>> https://www.ietf.org/mailman/listinfo/netmod
> 
> 
> -- 
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>
> 
> _______________________________________________
> netmod mailing list
> netmod@ietf.org
> https://www.ietf.org/mailman/listinfo/netmod

--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C