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Re: How to Version XML Applications

From: Anthony B. Coates <abcoates@TheOffice.net>
Date: Sat, 14 Sep 2002 21:07:53 +0100
To: www-tag <www-tag@w3.org>
Message-Id: <E17qJD2-0001Na-00@FUSNWR01-LRS>

** Reply to message from Norman Walsh <Norman.Walsh@Sun.COM> on Fri, 13 Sep
2002 14:19:57 -0400

> From the point of view of applications that examine the namespace name
> and local name of an element to determine the vocabulary to which it
> belongs, it isn't simply a "should never", it's a "can never".
> 
> To those applications, if you change the namespace name, you haven't
> changed the namespace of the vocabulary, you've *changed the
> vocabulary* by definition.

You change the definition in principle, but not necessarily in practice.  Not
that I would argue for versioned namespace URIs, but from an application
developer's point of view, detecting the versioned namespace URI and loading the
appropriate module for processing that version is no different to dealing with
other versioning situations.  Having detected the namespace, you would probably
ignore the namespace from there on and just use the local element names.  Odd
things might happen if someone embedded two versions of the same logical
namespace in the same document, but you would probably just set the application
to barf if that happened.

The important point is that for application developers, the barriers to using
using versioned namespace URIs are low and easily overcome, so it should not be
assumed that namespace versioning will die out via a process of natural
selection.

	Cheers,
		Tony.
====
Anthony B. Coates, Information & Software Architect
mailto:abcoates@TheOffice.net
MDDL Editor (Market Data Definition Language)
http://www.mddl.org/
Received on Saturday, 14 September 2002 16:08:41 GMT

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