Re: [NGO] external module properties

Ladislav Lhotka <lhotka@cesnet.cz> Tue, 29 April 2008 20:02 UTC

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From: Ladislav Lhotka <lhotka@cesnet.cz>
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Subject: Re: [NGO] external module properties
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Andy Bierman píše v Út 29. 04. 2008 v 12:16 -0700:

> Excellent point.
> I am envisioning a system which includes a mandatory standard
> 'schema-discovery' mechanism.  The <hello> exchange is a bad
> place for all this versioned module to namespace mapping info
> (even though that's exactly what I have implemented now ;-)

Why is it so bad? The big advantage I see is that it works with the
existing NETCONF framework.

> 
> The namespace URI should be stable.  It is assigned in
> the first version of the module.  It can never change.
> If the module is obsolete, the namespace is still 'used up',
> and can never be reused in another module.
> 
> In XSD, the <schema> 'version' attribute should be used in addition
> to the targetNamespace, to determine the exact schema content.
> In YANG, each new version of a module (std:MUST/vendor:SHOULD)
> include a new revision-stmt, which has a date string which becomes
> the new version identifier.

RELAX NG has no such attribute and nobody seems to be complaining.
Version numbers are indeed encoded in namespace URIs. In my view, the
revision statement could be interpreted as an auxiliary version marker
intended for human readers - the only authoritative identifier of a YANG
module content would be the URI.

Lada

-- 
Ladislav Lhotka, CESNET
PGP Key ID: E74E8C0C

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