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   Re: Tool X (was Re: simple question on namespaces.)

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  • From: Paul Tchistopolskii <paul@qub.com>
  • To: xml-dev@lists.xml.org
  • Date: Fri, 29 Dec 2000 14:46:24 -0800

----- Original Message ----- 
From: Jonathan Borden <jborden@mediaone.net>

>     The point has been raised that a namespace URI identifies a single
> schema (forget content negotiation for the moment). My point is that
> doctypedecls also identify a single schema, hence this problem is not new.

Not really. There are some differences.

1. doctypedecls are pointing to DTDs. They're pointing 
to some standard thing ( DTD is standard. Useless, but standard). 
Namespaces are poiting to nowhere.

> If this argument is used to claim 'namespaces are broken' as I've heard,
> then it equally claims 'XML 1.0 is broken'. Of course nothing is perfect, so
> everything is broken.

DTD layer in XML is of course broken ( because it does not survive in the 
real life for another W3C standards, like XSL FO, for example ), but let us 
forget about it.  

My point is that namespaces ( pointing to nowhere ) are broken in 
different way. 

2. Also, DTD layer could be ignored. I mean you can just not use DTD layer - 
and that's it. 

*Namespaces* are much harder to ignore. I still think the purpose 
of namespaces was/is  to assign a unique context, not to fetch the URLs.

Not that I enjoy bashing namespaces ( even I still think that SGML people 
were right and resolving form context is better than resolving from hidden 
'second-name' ), but I think that situation with namespaces is different
than situation with DTDs.

3. Let's think a bit about  the DTD layer. We have DTD. We have a 
doctypedecl. doctypedecl is like a PI. It says : "validate with this DTD".

Current semantics of namespace 'PI' is different. I'd say that the semantics 
of namespace PI is "handle prefixes/hidden lastnames".  Adding *more* semantics
to 'namespace PI' is just wrong, I think. It'll produce a monster 'PI' with 
2 orthogonal semantics attached. To me it smells like a suspicious step.

Again - I'm not sure I can say is it good or not ( in my universe there is 
no namespaces, because I think that resolution from the context is 
the way to go ) - but the point of this letter is explain what  
is different between namespaces and doctypedecls from my point of view.



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