Re: [netmod] questions about draft-rtgyangdt-rtgwg-device-model-00

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 19 August 2015 18:40 UTC

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Date: Wed, 19 Aug 2015 20:40:43 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Lou Berger <lberger@labn.net>
Subject: Re: [netmod] questions about draft-rtgyangdt-rtgwg-device-model-00
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Mail-Followup-To: Lou Berger <lberger@labn.net>, Andy Bierman <andy@yumaworks.com>, netmod WG <netmod@ietf.org>, draft-rtgyangdt-rtgwg-device-model@ietf.org, Routing WG <rtgwg@ietf.org>
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On Tue, Aug 18, 2015 at 09:38:04PM -0400, Lou Berger wrote:

> > Why is this a meta-model?

> because the aim to to show how other models inter-relate rather than
> define the details of all models. As stated in the intro:
> 
>    This document aims to provide an extensible structure that can be
>    used to tie together other models. It allows for existing, emerging,
>    and future models. The overall structure can be constructed using
>    YANG augmentation and imports.
>

You can easily extract relationships between YANG data models out of
YANG language constructs such as import relationships, leafref path
restrictions, augment references, etc.

- Why do you think relying on language constructs does not work?

- Why do you believe that relying on a certain hierarchy that several
  independent SDOs and vendors have to augment and fill consistently
  is going to be lead to a robust solution?

If YANG adoption continues as it looks right now, we will count
modules in the thousands in a couple of years originating from many
different organizations. I would trust tools that are able to
interpret YANG language constructs to scale up to such a scenario. I
doubt a simple hierarchy of containers (which will essentially become
unmaintainable once it is used by several standards) will be of much
value in 10+ years.

Andy's early work on YANG packages that provide machine readable
meta-data is a useful direction to explore further.

/js

PS: As a spare-time Unix system administrator, I recall several fancy
    proposals back in the 1990's how to best organize your /usr/local
    to make software installation and sharing easy. It seems none of
    these approaches that are essentially relying on naming
    conventions succeeded in the long run. Instead, we got software
    package systems that have sufficient machine readable
    meta-information to make software management easy and reliable.

-- 
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/>