Re: analysis of YANG vs. RELAX NG

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Tue, 04 December 2007 07:25 UTC

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Date: Tue, 4 Dec 2007 08:25:31 +0100
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Ladislav Lhotka <lhotka@cesnet.cz>
Subject: Re: analysis of YANG vs. RELAX NG
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References: <474D9194.3060103@ericsson.com> <953beacc0711281025w4d993dd7u77d729111074496c@mail.gmail.com> <20071128.230244.254578150.mbj@tail-f.com> <63F8A418-6AF0-4205-ACC7-53A8C7BC6A73@osafoundation.org> <47512728.6040201@gmx.de> <517bf110712021242v43c462f0v86267f591e5cdfbd@mail.gmail.com> <47543B30.1060409@andybierman.com> <1196704923.5569.14.camel@missotis> <003801c835e7$4fefeb20$6801a8c0@oemcomputer> <1196722786.5835.57.camel@missotis>
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On Mon, Dec 03, 2007 at 11:59:46PM +0100, Ladislav Lhotka wrote:
 
> I think it's a misunderstanding. I am not pleading for fuzzy (is it
> approximately what "mushy" means?;-) data models, the models can and
> should be simple and unambiguous, I am talking about additional
> flexibility for model *designers*, i.e., straightforward means for
> reusing and extending existing models into new models (also by adding
> structure to former leaves, why not?), and here I think YANG is rather
> rigid when compared to RELAX NG.

The question whether it is a good idea to be able to turn a data
containing XML element into a container element in a future revision
of a data model is pretty much independent of the schema language.

Several network management people believe that having XML elements
that sometimes are containers and sometimes leafs does not help
interoperability. In fact, we would likely require that any solution
(e.g. XSD-+ or RELAX NG-+ extended subset languages) does have
versioning rules attached that guarantee the same behaviour.

/js

-- 
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/>