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Re: How to Version XML Applications

From: <noah_mendelsohn@us.ibm.com>
Date: Fri, 13 Sep 2002 14:39:56 -0400
To: Norman Walsh <Norman.Walsh@Sun.COM>
Cc: www-tag@w3.org
Message-ID: <OF1D526CEA.251553F6-ON85256C33.00664ABD@lotus.com>

Norm Walsh writes:

> For XML-based
> [quoting Tim Bray...NRM]
> | languages, designers in general SHOULD NOT embed versioning
> | information in namespace names."  -Tim

> Sounds like good practice to me :-)

I think this is premature, or at least too categorical.  We haven't said 
what a version is and therefore what versioning information is.  That 
said, in the case of minor revisions, such as bug fixes, I suspect this is 
good advice:  don't change namespaces every time you add an optional 
attribute to an element.  In the case of a major evolution of a language, 
say HTML -> XHTML, I'm not so sure.  Who's to say that's not a "version" 
that deserves a new namespace, at least for its incompatible 
constructions, unless we define some terms?  I'm not sure we understand 
the cases in the middle where there are, perhaps, serious structural 
changes in a language that affect parts but not all of it.  If we 
completely reworked the table architecture in HTML, and left the rest of 
the language unchanged, should namespaces be used?  For just the new stuff 
or for everything?  What about the parents of the new stuff that now have 
(recursively up the tree) changed content models?  What if there is an 
incompatible change to an existing element (goes from MUST HAVE attribute 
to MUST NOT HAVE attribute)?  Are we really supposed to do all of this in 
one namespace?

If we think this is not the time to dive into these questions, I can 
understand that.  If so, I'm sort of nervous about giving advice on the 
use of namespaces without really working through the terminology and use 
cases carefully enough that we can tell, at least for practical purposes, 
what "versioning information" is, and when the advice should be applied. 

So my suggestion is:  either decide that this is the time to choose a 
group to think seriously though at least some of the versioning issues, or 
skip the advice on namespaces, at least for now.  Many thanks.

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Noah Mendelsohn                              Voice: 1-617-693-4036
IBM Corporation                                Fax: 1-617-693-8676
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For XML-based
| languages, designers in general SHOULD NOT embed versioning
| information in namespace names."  -Tim

Sounds like good practice to me :-)
Received on Friday, 13 September 2002 14:41:37 GMT

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