Re: [netmod] augment YANG 1.0 with YANG 1.1 OK?

[Andy Bierman <[e-mail]>]

On Wed, Oct 18, 2017 at 2:36 PM, Juergen Schoenwaelder <
[e-mail]> wrote:

> On Wed, Oct 18, 2017 at 01:26:30PM -0700, Andy Bierman wrote:
> > On Wed, Oct 18, 2017 at 7:36 AM, Juergen Schoenwaelder <
> > [e-mail]> wrote:
> >
> > > On Sun, Oct 15, 2017 at 12:56:42PM -0700, Andy Bierman wrote:
> > > > > >
> > > > > >   augment "/if:interfaces-state/if:interface" {
> > > > > >     action reset {
> > > > > >       description "Reset this interface";
> > > > > >     }
> > > >
> > > > Can you spot the NMDA problem above?
> > > > Actually, it exists for in-line definitions, not just augment.
> > > >
> > > > Once you collapse the interfaces-state tree into /interfaces, there
> > > > is no way to specify whether an action is intended for <operational>
> > > > or a configuration datastore, or all datastores.
> > >
> > > I think operations (both RPCs and actions) by default always execute
> > > in the context of the operational state datastore. This is consistent
> > > with the way we define the xpath context. An operation that operates
> > > on other datastores needs to carry this information in its semantics
> > > and typically requires special arguments to select the datastores
> > > affected. This is how <get-config> and <edit-config> work. Hence, a
> > > reset action defined for an interface by default applies to the
> > > operational state datastore. And this default makes likely sense for
> > > most actions and RPCs.
> > >
> > > If an action or RPC is expected to operate on a different datastore,
> > > the description must explain this and there may be a need to pass a
> > > datastore identifier to the operation. [Yes, in retrospect, one might
> > > have designed the protocol differently so that there would always be a
> > > datastore parameter at the protocol level but its too late for that.]
> > >
> > >
> >
> > IMO this needs to be simple and deterministic.
> > All YANG actions in an NMDA server are invoked against <operational>.
> >
>
> Well, yes, like all RPC operations - except that we have RPC
> operations that do act on other datastores. ;-) But the generic
> mechanism including any xpath contexts is against operational.  If the
> semantics of the operation that say 'interpret parameter 5 as a
> datastore name and act on that datastore', well then this is what the
> designer wanted. This is how edit-config and friends work today.
>
>

Except this approach is ad-hoc and sub-optimal.
That's why NMDA <get-data> is better (because it is extensible yet not
ad-hoc).
IMO an <action2> wrapper would be a good addition for a YANG update

  <action2>
     <datastore>rd:running</datastore>
     <top>
         <foo>
           <test-action>
               ...
          </test-action>
        </foo>
   </top>
  </action2>

It is better to keep the YANG model decoupled from datastores,
and use a protocol parameter to make it explicit.


/js
>


Andy


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