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RE: rdf in practice

From: Weiss-Lijn, Mischa <Mischa.Weiss-Lijn@ptp.sira.co.uk>
Date: Thu, 4 Nov 1999 13:51:51 -0000
Message-ID: <81F2439516D8D011885D0060978F10DA147A6A@FOCUS>
To: "'alison@cee.hw.ac.uk'" <alison@cee.hw.ac.uk>, "'www-rdf-interest@w3.org'" <www-rdf-interest@w3.org>, "'xsl-list@mulberrytech.com'" <xsl-list@mulberrytech.com>
You've done some very nice work here with XSL-T and RDF, and I am very
tempted to follow you lead and stick to using RDF.  

But I am still unsure about how one could use this set up to select
particular pieces of xml content from within a file according to the RDF
metadata associated with them.  

For example say you have a large report and you want to filter it so that
you only see the introduction of each chapter.  You could have the report
marked up in XML, and particular peices of it could be refered to in the RDF
file with XPATH and asssociated with metadata (e.g. 'introduction').  

I don't see how you could use XSL-T to use the information in the RDF file,
or even it doing that would make sense.  

Using RDF would mean separating the metadata from the XML document content.
But some of the metadata concerns the structure of the document content.
This structure would surely be more richly encoded in a DOM tree.  If there
is no structure in the XML document then XPath references to individual
pieces of content would have to use ID attributes, which are currently
supported my most parsers.

Can you offer any wisdom on these questions.

		Mischa 


	----------
	From:  alison@cee.hw.ac.uk[SMTP:alison@cee.hw.ac.uk]
	Sent:  Thursday, November 04, 1999 11:17 AM
	To:  Mischa.Weiss-Lijn@ptp.sira.co.uk
	Subject:  Re: rdf in practice


	> I don't see how these tools can be practically used with RDF.  RDF
can not
	> be mixed with non-RDF XML, which makes it very hard to use XSLT to
	> manipulate XML content according to the metadata it is associated
to.  It
	> seems much easier to encode the metadata as XML, and abandon RDF
altogether.
	> Can you suggest a way round this?  Can any of you give good
justifications
	> for the extra work needed to use RDF?

	I'm a bit of a novice at this, but I've been using XSLT with RDF.
	(Mainly to try and present metadata to the user in a way that
	depends on a user profile).

	To use XSLT I keep the "pure" RDF in separate files, and have an XML
wrapper
	that includes the RDF within some other XML; The XML wrapper
	specifies the stylesheet. (The following inserts an RDF schema
	into a bit of XML, and specifies a stylesheet for that)

	<?xml version="1.0"?>

	<?xml-stylesheet type="text/xsl" href="schemaselect.xsl" ?>
	<!DOCTYPE SW [
	<!ENTITY schema SYSTEM "schema.rdf">
	]>

	<SW>
	&schema;
	</SW>

	I've used Explorer 5, and also used XT (James Clarks XML+XSL
processor)
	on the server-side. It seems better to use XT, and wait until
	Explorer has a version with a more up to date XSL processor.

	I'm sure you'll get some better technical replies, but this
	is from the perspective of someone who has only spent a month or
	so learning the relevant technologies!

			Alison

	(Some of the RDF presented via XSL is at
	http://www.cee.hw.ac.uk/~alison/mirador/xml/demo.html)
	
Received on Thursday, 4 November 1999 08:48:41 GMT

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