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RE: RDF Issue: mime-types-for-rdf-docs

From: Pierre-Antoine <pa@champin.net>
Date: 09 Apr 2002 21:16:19 +0200
To: Danny Ayers <danny666@virgilio.it>
Cc: www-rdf-comments@w3.org
Message-Id: <1018363669.718.52.camel@calvin>
On Tue, 2002-04-09 at 00:50, Danny Ayers wrote:
> I may be completely off the mark here (I'm certainly no Marcel Marceau), but
> I think perhaps MIME stumbles a bit around this point - text/xxx image/xx
> application/xxx seems a bit too much like a short-term shortcut for
> application developers, a hangover from the days before standard formats
> could better describe themselves. Pandering to today's (HTML+) textual
> document browsers, even.
> I would have thought that any system that gets application/rdf+xml shouldn't
> have trouble deciding whether it's pics, xpackage or annotea, *after* the
> header, in an intermediate routing layer. Going further, RDF can pretty well
> contain information about anything, or at least from any namespace. To try
> and prescribe a specific receiver for the data when fed over http (or
> whatever) whould strike me as a lost cause - a generic RDF reader/parser
> with routing rules governed by local preferences would strike me as a much
> more promising approach. The exact same data received by my 'environmental
> concerns' agent would presumably need different handling that received by my
> 'teak commodities' agent.

I am only half agreeing with you, Danny.

1. About the parser recognizing the type

If I push your argument one step further, why wouldn't any XML parser be
able to recognize that a document is RDF or SVG, and then behave
correctly ?
The first part of the assertion (recognizing) is technically feasible
(just check the namespace of the root element); but the second one
(behaving) is not.

As well as you need a specialized parser to handle SVG documents
(meaning, a parser able to actually draw the graphics), you need
specialiazed RDF parsers to handle picx, xpackage or annotea content.

Hence it looks consistent to me to create specialized mime-types for
those. It does not mean that a more general parser can not do *anything*
with these types: indeed, an XML parser won't be totally useless with
some application/pics+rdf+xml content. This is the whole point of the
"+xml" suffix.

2. About mixing namespaces

It is true that, with RDF even more than XML, content types can be
intermingled: an XHTML document may contain embeded SVG, but this
"embeded" part can quite easily be isolated and redirected to the
appropriate specialize parser. In RDF, isolating parts related to a
particular namespace may be a puzzle.

Anyway, I think that there are a lot of situations where it is possible
(and easier) to see an RDF graph as 
 - conforming to a particular schema (say, the "primary" schema),
 - and *enriched* by additionnal information from other schemas (say,
"additionnal" schema)
even though the "primariness" of the schema is not intrinsic to the
graph, but just determined by a contextual choice (for example, to
conform with the types acceptable by the client, like in HTTP).


Received on Tuesday, 9 April 2002 15:17:36 UTC

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