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Re: Comments on the architecture doc

From: Mark Baker <distobj@acm.org>
Date: Mon, 4 Feb 2002 12:16:49 -0500 (EST)
Message-Id: <200202041716.MAA23197@markbaker.ca>
To: paul@prescod.net (Paul Prescod)
Cc: www-tag@w3.org
> I wasn't really talking about how this maps into the MIME system at all.
> I was just pointing out that we are going down the wrong path if we try
> to associate machine readable specifications with namespaces and then
> apply them to parts of the document tree dynamically. Namespaces (as
> defined today) do not represent useful "languages" or "document types"
> as Tim and Tim implied.
> 
> To put it another way, the (URI, localname) pair is opaque, just as URIs
> are opaque. You would never try to associate processing with URIs that
> began with "www.*" instead of "ftp.*". So why does it make sense to try
> and associate processing with (http://www.w3.org/1999/xhtml, *)? It's
> the same deal. 

No, it's a different deal because the HTML WG has told everybody that
"http://www.w3.org/1999/xhtml" identifies XHTML, in a similar way to how
it told us that "text/html" identifies HTML.

The opacity issue only relates to the URI syntax; you can't assume that
XHTML was produced in 1999, for example.

> XML needs to have well-defined rules. If the "new rule" is that the root
> namespace is magical then XSLT should just be changed to conform. It
> would be very confusing if the root namespace was sometimes magical. You
> would save a document to your hard disk and find that it behaved
> differently than when it was on the Web...unless there was a new file
> extension. Which gets even more confusing.

Right.  So let's write down the rules and figure out how to deploy them.

> > My soon-to-be I-D on this topic is;
> > 
> > http://www.markbaker.ca/2002/01/draft-baker-generic-xmlns-dispatch
> 
> If you buy the argument, (which I don't) that namespaces are the right
> thing to trigger off of, then why wouldn't you just put the namespace in
> the MIME type either using Simon's trick

You can, but you can't dispatch fine grained processors from it.

If you knew that you had one big monolith of a processor that did XHTML,
SVG, SMIL, and MathML, then you could dispatch any document with a
proper subset of those namespaces (as declared by Simon's trick) to that
processor.

But we're trying to solve the problem of fine grained dispatching, where
you can use processors that only know one namespace.  That can't be done
with Simon's draft alone (though it may prove a useful optimization for
ahead-of-time instantiation of the component processors).

> or using a URI->mime type
> mapping: http://www.ietf.org/internet-drafts/draft-eastlake-cturi-03.txt

Not granular enough.

MB
-- 
Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Monday, 4 February 2002 12:14:36 GMT

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