[netmod] example modules in 6087bis

Martin Bjorklund <mbj@tail-f.com> Mon, 16 January 2017 15:48 UTC

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Date: Mon, 16 Jan 2017 16:48:03 +0100 (CET)
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From: Martin Bjorklund <mbj@tail-f.com>
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Subject: [netmod] example modules in 6087bis
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Hi,

It turns out that the recommendations on example modules are a bit
unclear.  Different drafts do very different things.  Some examples:

https://tools.ietf.org/html/draft-ietf-i2rs-yang-l3-topology-08#section-6.1.2

This example module really looks like a real module.  It uses an
IANA-controlled namespace, and the meta-statements indicate that this
is a normative modules.  But the module does not use the <CODE> tags.


https://tools.ietf.org/html/draft-ietf-netconf-restconf-18#appendix-C.1

This module is better, but it is written to follow RFC 6087 rules
(pass pyang --ietf), with the result that it contains a bit of "noise"
with some meaningless descriptions and meta-statements.  It also does
not use <CODE> tags.


A good example (IMO) is found in
https://tools.ietf.org/html/rfc8022#appendix-C

It uses descriptions when necessary (high s/n), no fake
meta-statements etc.

However, it might be a good idea to require example modules to have a
"description" statement that explains what the module examplifies.
For example, the example-rip could have:

  description
    "This example module demonstrates how the core routing data model
     can be extended to support a new control-plane protocol.  It is
     intended as an illustration rather than a real definition of a
     data model for the Routing Information Protocol (RIP).";



I think that 6087bis is clear when it says:

  The guidelines in this document refer mainly to a normative complete
  module or submodule, but may be applicable to example modules and
  YANG fragments as well.

I think this states that example modules do not have to pass pyang
--ietf.


In order to make this more clear, I suggest the following changes to
draft-ietf-netmod-rfc6087bis-09

In the Terminology section 2.4:

NEW:

  o  Example module:  A complete YANG module or submodule that is
     intended to illustrate some specific aspect, but not intended for
     actual use.


In section 4:

NEW:

   All normative modules or submodules, example modules or submodules,
   and example YANG fragments MUST be valid according to RFC 7950,
   except when they are used to illustrate some illegal constructs.


In Section 4.2.1 "Example Modules":

NEW:

  An example module SHOULD have a namespace on the form

    o  http://example.com/<module-name> OR
    o  urn:example:<module-name>

  An example module SHOULD have a description statement that describes
  that it is an example module, and what it examplifies.

  An example module SHOULD NOT have any additional meta-statements
  (i.e., "organization", "contact", or "reference").

  An example module SHOULD use the "description" statement in any
  definition where it is required to understand the example.




/martin