Re: [netmod] <running> vs <intended>

[Andy Bierman <[e-mail]>]

On Mon, Sep 18, 2017 at 11:07 AM, Martin Bjorklund <[e-mail]> wrote:

> Juergen Schoenwaelder <[e-mail]> wrote:
> > On Mon, Sep 18, 2017 at 05:17:46PM +0100, Robert Wilton wrote:
> > >
> > > > No.  I do not agree that the MUST in RFC 7950 can be removed.
> > > > I do not agree the architecture should update YANG at all.
> > > OK.
> >
> > I am with Andy here. <running> has always had the requirement to be
> > valid and we are not supposed to change that. Mechanisms for inactive
> > configuration or templating must be designed to be backwards compatible
> > I think.
>
> Ok.  If we keep the requirement that <running> in itself must be
> valid, it just restricts the usefulness/expressiveness of inactive and
> template mechanisms, but it might be ok.
>
> I think that even w/o this requirement, the observable behavior for a
> client can be backwards compatible.  For example, suppose we have an
> inactive access control rule that refers to a non-existing interface in
> <running>.  If a client that doesn't know anything about inactive asks
> for the contents of <running>, our implementation removes the inactive
> nodes from the reply to the client.  Only a client that opts-in to
> inactive will receive a reply with things that looks invalid if you
> don't take the inactive annotation into account.
>
>
>
There are many ways that validation can fail because inactive nodes are
present,
and considered part of the validation.

e,g, min-elements, max-elements, mandatory, unique.

I think we all agree that validation on the enabled nodes is supposed to
continue to work.

Here is an attempt at a backwards-compatible solution:

1) current <get-config> and <get> responses only include enabled nodes.
2) old-style <edit-config> operations do not alter inactive nodes
3) NMDA clients use <get-data>, not <get-config> or <get>.  These responses
    include enabled and disabled nodes, so validation does not apply for
<running>
4) new style <edit-config> (i.e. <datastore> parameter used) can alter any
type of data node

Note that the YANG MUST rule still applies, because validation is only done
on enabled nodes.
It is only the response message representations that cannot be validated,
not the contents
of <running> on a server.



> /martin
>

Andy