Martin Bjorklund <[email protected]> writes:

> Andy Bierman <[email protected]> wrote:
>> On Thu, Oct 15, 2015 at 3:34 PM, Juergen Schoenwaelder <
>> [email protected]> wrote:
>> 
>> > On Tue, Oct 13, 2015 at 09:19:45AM -0700, Andy Bierman wrote:
>> > >
>> > > Conformance to YANG for the extension: NONE This includes syntax and
>> > > semantics.  It makes no sense at all (Lada is right) to say the
>> > > extension semantics apply.  They only apply if the tool supports the
>> > > extension.  Conformance to the extension is a different matter.
>> >
>> > I would hope that a server supporting NACM implements the behaviour of
>> > nacm:default-deny-write when nodes are tagged with this extension.
>> > Sure, a YANG parser is allowed to skip over nacm:default-deny-write
>> > but if nacm:default-deny-write is used for a certain node, I think we
>> > want the server to implement the semantics implied by
>> > nacm:default-deny-write regardless which tool the developer used.
>> >
>> >
>> I do not agree.
>> The semantics for this YANG extension only apply to NACM.
>> Of course an implementation of NACM cannot ignore this extension.
>
> +1
>
> So the question is if we need to add/change any text in 6020bis?

IMO, two things:

1. Clarify the text about parser/compiler behaviour - or remove it.

2. State that conformance with respect to extensions is outside the
   scope of YANG spec.

As for #1, I think parser behaviour is totally irrelevant - a parser is
supposed to do what the application or protocol implementation expects
it to do. One could use a parser that ignores everything except module
names, and it can be perfectly OK for a given application.

What we could say is that extensions MUST NOT affect the validity of
datastores, RPC messages and notifications, i.e., when validating an
instance document against a YANG data model, all extensions are
ignored. This is essentially the approach of RELAX NG towards
foreign-namespace annotations. But then the "annotation" extension would
most likely be illegal.

Lada

>
>
> /martin
>
>> 
>> The extensions says what to do in NACM if the tag is found.
>> (As it should).  It does not define any behavior outside of NACM.
>> No other tool except a NETCONF server implementation
>> of NACM has any conformance requirement to implement this extension.
>> 
>> 
>> /js
>> >
>> 
>> 
>> Andy
>> 
>> 
>> >
>> > --
>> > 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/>
>> >

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

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