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Re: XML validity and namespaces

From: Robin Berjon <robin.berjon@expway.fr>
Date: Mon, 04 Apr 2005 01:32:57 +0200
Message-ID: <42507D29.8080902@expway.fr>
To: noah_mendelsohn@us.ibm.com
Cc: www-tag@w3.org

noah_mendelsohn@us.ibm.com wrote:
> Rich Salz writes:
>>XML validity is important, and perhaps should be separated from DTD's.
> 
> I have commented a few times on what I take to be one of the great ironies 
> of XML:  The "Extensible" Markup Language is very extensible with respect 
> to constructs such as attributes and elements, but very inflexible in 
> (not) allowing for replacement or evolution of its core mechanisms such as 
> DTDs. 

And is it not one of the greatest ironies of XML Schema that it failed 
to learn from that lesson and therefore didn't provide simple and 
straightforward means to describe extensibility in schemata?

I don't disagree with Paul that part of Rich's question can be deflected 
over to XML Core, but I does seem to me that other parts of it smell 
like TAG fodder. Within the XML architecture, is it commendable to use 
DTDs knowing that they do cannot validate namespaced documents? Knowing 
that all document-oriented languages are built to expect foreign 
namespaces practically everywhere, is XML Schema built to know enough 
about extensibility or is it, as some malicious voices would put it, 
just "ML Schema"? Are we not missing a piece comparable (or equal) to 
NVDL somewhere?

> All 
> attempts I've seen to inline schemas into the instance wind up with the 
> schema as part of the element tree, where it doesn't belong.  Amusingly, 
> this means that if the schema is for the whole document, it has to 
> validate its own existence!

Which is a clear demonstration of the limitations in XML Schema that 
currently prevent document formats that intend to live in an open world 
to use it. It really shouldn't be that hard to say "I want to validate 
my namespace, and the others can do whatever it is they want".

-- 
Robin Berjon
   Research Scientist
   Expway, http://expway.com/
Received on Sunday, 3 April 2005 23:33:00 GMT

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