Re: [Netconf] I-D Action: draft-ietf-netconf-rfc7895bis-05.txt

[Ladislav Lhotka <[e-mail]>]

On Mon, 2018-03-05 at 15:22 +0000, Robert Wilton wrote:
> Hi Lada,
> 
> I think that this is just the server providing erroneous data (i.e. 
> option 1 below), and as such I think that a client is at liberty to do 
> whatever it deems most appropriate.  E.g. I suspect that I would code a 
> client to do (2).

Whereas the server implementor may go for (3), which results in possible
interoperability problems.

> 
> Note, that the deviation leaf-list is a leafref back to the module 
> list.  Hence, for the YANG instance data to be valid, any entries in the 
> deviation list must be included in the modules list.

Hmm, even this is actually not true - the type should have

  require-instance true;

right?

But anyway, my point is the opposite direction - a deviation module is in the
"module" list but not in the "deviation" leaf-list.

> 
> In theory, a server could populate the module list with deviations but 
> not the deviation leaf-list.  However, there is no indication in the 
> module description that this is a valid thing to do, or that this 

But neither is there any indication that it is an invalid thing to do. Having
the deviation modules only in the "module" list would be perfectly sufficient.

> information is optional.  Stating that this specific information is 
> mandatory might then imply that some of the other data in YANG library 
> is optional, when it isn't.
> 
> In short, having looked at it again, I'm still of the opinion that the 
> current text is sufficient.
> 
> Do you still think that we need to clarify this further?

If "module" and "deviation" are required to match, the document should say so.

Lada

> 
> Thanks,
> Rob
> 
> 
> On 05/03/2018 14:26, Ladislav Lhotka wrote:
> > Martin Bjorklund <[e-mail]> writes:
> > 
> > > Hi,
> > > 
> > > This version addresses the WGLC comments.  Specifially, the module
> > > list now havs leaf-lists feature/deviation, import the term "implement
> > > a module" from RFC 7950, rather than redefining the term in this
> > > document, fixed some typos, fixed the examples to validate, updated
> > > references.
> > 
> > The draft should address the situation where one or more implemented
> > modules containing deviations are not listed in the "deviation" leaf-list
> > of the deviated module.
> > 
> > Currently the contents of the deviation list from sec. 3 is ambiguous in
> > this situation because
> > 
> > 1. such a situation might be considered as an error in server
> > implementation, but it doesn't follow from the document.
> > 
> > 2. deviations from implemented modules are applied no matter what the
> > "deviation" leaf-lists say.
> > 
> > 3, the "deviation" leaf-lists are authoritative, i.e. deviations
> > appearing in other modules are ignored.
> > 
> > I would personally prefer #3 because it is easiest to handle for both
> > server implementors and clients.
> > 
> > Lada
> > 
> > > 
> > > /martin
> > > 
> > > 
> > > 
> > > [e-mail] wrote:
> > > > A New Internet-Draft is available from the on-line Internet-Drafts
> > > > directories.
> > > > This draft is a work item of the Network Configuration WG of the IETF.
> > > > 
> > > >          Title           : YANG Library
> > > >          Authors         : Andy Bierman
> > > >                            Martin Bjorklund
> > > >                            Juergen Schoenwaelder
> > > >                            Kent Watsen
> > > >                            Robert Wilton
> > > > 	Filename        : draft-ietf-netconf-rfc7895bis-05.txt
> > > > 	Pages           : 32
> > > > 	Date            : 2018-02-27
> > > > 
> > > > Abstract:
> > > >     This document describes a YANG library that provides information
> > > >     about the YANG modules, datastores, and datastore schemas used by a
> > > >     network management server.  Simple caching mechanisms are provided
> > > > to
> > > >     allow clients to minimize retrieval of this information.  This
> > > >     version of the YANG library supports the Network Management
> > > > Datastore
> > > >     Architecture by listing all datastores supported by a network
> > > >     management server and the schema that is used by each of these
> > > >     datastores.
> > > > 
> > > >     This document obsoletes RFC 7895.
> > > > 
> > > > 
> > > > The IETF datatracker status page for this draft is:
> > > > https://datatracker.ietf.org/doc/draft-ietf-netconf-rfc7895bis/
> > > > 
> > > > There are also htmlized versions available at:
> > > > https://tools.ietf.org/html/draft-ietf-netconf-rfc7895bis-05
> > > > https://datatracker.ietf.org/doc/html/draft-ietf-netconf-rfc7895bis-05
> > > > 
> > > > A diff from the previous version is available at:
> > > > https://www.ietf.org/rfcdiff?url2=draft-ietf-netconf-rfc7895bis-05
> > > > 
> > > > 
> > > > Please note that it may take a couple of minutes from the time of
> > > > submission
> > > > until the htmlized version and diff are available at tools.ietf.org.
> > > > 
> > > > Internet-Drafts are also available by anonymous FTP at:
> > > > ftp://ftp.ietf.org/internet-drafts/
> > > > 
> > > > _______________________________________________
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> > > > 
> > > 
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> 
> 
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67