Subject: [netmod] Consensus call: With-Defaults as SHOULD in 4741bis

From: "Ersue, Mehmet (NSN - DE/Munich)" <[email-masked]>
Date: Fri, 20 Nov 2009 19:32:30 +0100

Hi All,

in the NETCONF/NETMOD conference call we discussed the 
handling of with-defaults in 4741bis document and the 
YANG specification.

We had a rough consensus on having 'with-defaults' as 
SHOULD to implement (see point 3 in the attached mail 
from October 02, 2009), which is going to be added to 
the 4741bis document if we have consensus.

We do not want to go through a re-run of all arguments 
for and against. Since this conclusion has an impact 
on both NETCONF 4741bis and the YANG specifications 
the co-chairs of NETCONF and NETMOD WGs are keen of 
having a final consensus call on that. 

All on NETCONF and NETMOD WG maillists, please read 
the attached mail of David Partain and respond to this 
mail by December 1, 2009 EOB PT.
 <<[netmod] Information from chair phone call on 24 September>> 

If you agree with the conclusion having 'with-defaults' 
as SHOULD to implement in 4741bis please state so.
If you disagree with this consensus, state your opinion too.

Thank you.

Bert & Mehmet

Subject: [netmod] Information from chair phone call on 24 September
From: "ext David Partain" <[email-masked]>
To: <[email-masked]>, "NETMOD Working Group" <[email-masked]>
Date: Fri, 2 Oct 2009 09:36:19 +0100

Hi,

This mail summarizes the conversation that the 4 co-chairs of
NETCONF/NETMOD had with interested parties on default issue.
This mail is NOT intended to re-open the question about default
handling but to confirm that what we believe is a reasonable way
forward is a decision that the working groups can live with.
Silence will be considered consent!

1. There were a number of comments during the call that indicated
that we need text that says that defaults are taken into
consideration in validation.

2.  The defaults question: No fundamental changes to the model
are needed.  That is, a server MAY choose not to send back values
that are the default as defined in the YANG model.  Instead, we
are going to try to address some things that will tighten up
potential inconsistencies (to "SHOULD level", not "MUST level")
in dealing with defaults.  There are cases where you don't
necessarily know what a non-answer about an object with a default
clause means.  In particular, this means looking at upgrade
rules, dealing with leafrefs and instance-identifiers.  We should
try to address the most common cases without trying to cover all
possible corner cases. We need specific text, which Andy and
Martin have been asked to address.

Again, we are not re-opening this discussion by sending this
mail: we wish to confirm that this is the right way forward.

Some expressed a wish that there be a simple, short explanation
of how defaults are handled in general so that one doesn't need
to be privy of the entire YANG history to understand why things
are the way they are.  If you believe that this is useful, please
offer text or, at a minimum, point out where you think text is
missing.

3. The NETCONF WG to check consensus on whether 'with-defaults:'
should be a SHOULD to implement.

4. In conjunction with the 'with-defaults:' work, the NETCONF WG
can consider adding an XML attribute in a report-all response
that tags default data as such to help NETCONF applications.
(This discussion is already underway.)

5. Juergen agreed to help with some examples of XPath expressions
refering to config / non-config / garbage data.  (I think I got
this right.)  If others believe that other examples are needed,
please suggest that on the mailing list.

6. We need to start thinking about (and writing about) the issue
of config vs. statistics vs. operational data.  This is something
that needs to be given serious thought and energy.  This will be
done separately (and after) the YANG work is complete.

7. We will try to put text in the architecture draft as a sort of
"placeholder" with respect to #5.  Text has been suggested on the
mailing list before and that should be put into the draft.

Thanks.

David

_______________________________________________
netmod mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/netmod

---

From: Phil Shafer <[email-masked]>
Date: Fri, 20 Nov 2009 13:40:09 -0500

>the 4741bis document if we have consensus.

As previously pointed out, the conf call's concensus was to ask the
NETCONF mailing list about w-d, not that it was a SHOULD.

>If you disagree with this consensus, state your opinion too.

I do not want W-D to be a SHOULD requirement since it is not required
for the proper operation of a NETCONF server.  We have managed
without it for a long long time and I do not see it as vital.  Heck,
there's no requirement in NETCONF for the data model to even _have_
default values.  4741 current says nothing about the data model's
contents and says absolutely nothing about default values.  I don't
see a convincing reason why this should change.

Thanks,
 Phil

---

From: David Partain <[email-masked]>
Date: Mon, 30 Nov 2009 15:00:53 +0100

Greetings,

> as SHOULD to implement in 4741bis please state so.

+1 

or...

Yes, I agree with this conclusion.

Cheers,

David

---

From: "Mark Scott" <[email-masked]>
Date: Mon, 30 Nov 2009 10:57:30 -0500

+1 in favour of SHOULD.

Mark

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-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of David Partain
Sent: Monday, November 30, 2009 9:01 AM
To: [email-masked]; NETMOD Working Group
Subject: Re: [netmod] Consensus call: With-Defaults as SHOULD in 4741bis

Greetings,

+1 

or...

Cheers,

David