Subject: [netmod] defaults wrap-up

From: Andy Bierman <[email-masked]>
Date: Fri, 25 Sep 2009 09:51:14 -0700

Hi,

There were some action items that came out of the conf-call
yesterday.  One of them is for Martin, myself and others
to somehow describe the known corner-cases which impact
the reliability of the meta-data used to synthesize defaults.

I would like the YANG Usage Guidelines to capture all
the good and bad practices wrt/ defaults.  The YANG draft text
is spread out and hard to follow, so a summary in the guidelines
draft is needed.

It seemed like we were close to consensus on the
module capability advertisement text.  I would like
the text to say the server MUST advertise all the YANG
modules/revisions it is using.  It should be obvious that
multiple revisions within a single server is most relevant
to typedefs, not objects.  Most server developers will
choose to support only the latest revision of an accessible
object, rpc, or notification, not multiple revisions.

Therefore, the only way multiple capabilities for
the same module will occur is through the import/include
by-revision ripple effect.

So modules of just groupings and typedefs are far
more likely to need a capability URI than any other
YANG construct.  Since their namespace URI doesn't
show up in any NETCONF <rpc> PDU, the <hello>  module capability
may be the only chance the client has to match a module name/revision
to a namespace-stmt.  (The netconf-state/schemas tree is optional.)

Andy