Re: [netmod] Order of evaluation for when?

Thu, 22 Oct 2015 03:46:16 -0700

Hello,
I STRONGLY agree with Andy, Interfaces MUST work the same way. Autodeletion MUST work or NOT work for all interfaces (Netconf, Restconf, CLI, GUI, etc.) the same way. IMO it is not a protocol issue. It is part of the YANG definition.

The whole idea behind model driven OAM is that we have one model that works (mostly) the same way on all interfaces. The more differences we have the less usable the product, the more difficult to implement.
regards Balazs

On 2015-10-21 15:07, Andy Bierman wrote:


On Wed, Oct 21, 2015 at 5:46 AM, Ladislav Lhotka <[email protected]> wrote:

> On 21 Oct 2015, at 14:33, Andy Bierman <[email protected]> wrote:
>
> Hi,
>
> IMO we do not need lots of rules for when-stmt.
> They are harder to enforce than just implementing the auto-deletion.
>
> Note that auto-deletion also applies to nodes already in candidate or running.
> It is just a derivative case to have a newly-created node deleted right away.
> If you add node /foo it may cause node /bar and node /baz to get deleted.
>
> I strongly object to treating a false when-stmt in a datastore validation
> as an error.  This is not how YANG 1.0 works, and this is not
> backward-compatible.

I think it has nothing to do with YANG (1.0 or whatever), and RFC 6020 correctly describes this auto-deletion behaviour for "choice" in sec. 7.9.6 NETCONF <edit-config> Operations. It is indeed protocol business - YANG spec should just define what's valid and what isn't.

IMO RESTCONF spec doesn't require auto-deletion.



Our server uses the same validation engine for both protocols.
RESTCONF does not change the behavior of YANG in any way.
I don't see how YANG validation procedures would not apply to RESTCONF.

YANG says that the node semantics apply IFF the when-stmt evaluates to true.
It is up to the implementation to enforce that.  It applies to server-created
nodes or nodes created via some protocol.


Lada

Andy
 

>
>
> Andy
>
>
> On Wed, Oct 21, 2015 at 5:16 AM, Balazs Lengyel <[email protected]> wrote:
> Hello Martin,
> I would want to codify this. My earlier proposal was:
>
> - when MUST NOT be dependent on a data node controlled by a when or choice statement
>
> Notice the strong MUST NOT statement. This would simplify life greatly.
> regards Balazs
>
> On 2015-10-20 10:09, Martin Bjorklund wrote:
> I have never seen anyone trying to refer to the conditional nodes in a
> when _expression_ - simply b/c it doesn't make any sense.
>
> --
> Balazs Lengyel                       Ericsson Hungary Ltd.
> Senior Specialist
> ECN: 831 7320
> Mobile: +36-70-330-7909              email: [email protected]
>
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--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C






-- 
Balazs Lengyel                       Ericsson Hungary Ltd.
Senior Specialist
ECN: 831 7320                        
Mobile: +36-70-330-7909              email: [email protected] 




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