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Re: Transforming XML content into RDF assertions

From: Murray Spork <m.spork@qut.edu.au>
Date: Mon, 07 Oct 2002 11:57:07 +1000
To: www-rdf-interest@w3.org
Message-id: <3DA0E9F3.9040408@qut.edu.au>

m batsis wrote:


> IMHO the bottleneck is not in the transformation; this can be done in 
> many ways (XSLT, SAX, put your stuff here) or it may not happen at all. 
> The problems are in the complexity of such a transformation result or 
> the actual XML. Almost any XML can be interpreted as RDF but some of the 
> challenges are:
>  * The amound of unneeded information and the proccess of filtering this 
> out of the transformation result.

The RSS 2.0 folks seem to be claiming the opposite - that an RDF syntax 
causes unnecessary verbosity and that their XML-only syntax is much cleaner.

>  * The result RDF can only be considered as a temporary graph that 
> cannot really be merged with others, unless there is a way to avoid 
> inconsistency between resource identifiers (which may be different for 
> the same resource in different transformations).

I don't understand why this would be the case - surely this is just a 
matter for how the XSLT transform is written?

> If the XML has been designed with RDF in mind (avoiding meaningless 
> containers and using URIs or IDs to identify what RDF sees as subjects) 
> then the problem is much easier to solve.

I guess the more general the XML -> RDF transform mechanism - the more 
likely you are to run into these problems. I've been much less ambitious 
-  my transforms are pretty specific - I write them with a particular 
XML -> RDF transform in mind. The problems you mention above then tend 
to dissapear - at least the structural ones do - identification is 
always going to be problematic I feel - but then I think this problem is 
general to RDF and not neccessarily specific to XML -> RDF transforms.

I do try to make the identification of resources (in my general XML 
documents) as RDF frielndly as possible - that means using URIRefs where 
possible (especially if the resource in question has been defined by 
another party) - or ids that are easily transformable into URIRefs.

In the case of RSS 2.0 (I haven't looked too deeply into this) I assumed 
that everyone would be using the same XSLT doc to do RSS 2.0 -> RDF 
transform - this transform would imbed the logic associated with 
identification of resources and therefor everyone is still using a 
consistent identifiaction scheme (well - at least as consistent as RSS 

[BTW - please don't take this as me supporting RSS 2.0]

> Personally, when designing XML schemas for clients, I find it much 
> easier to use something close the RDF model than a fancy XML one with 
> sections in the document grouping statements etc. The result is simple 
> and predictable while code designed for it can be highly reusable.

I tend not to worry too much what the impact of structure in my XML doc 
will have on an RDF view - I just design the XML doc to do the job I 
want it do do - then if I want to do RDF stuff with it afterwards I'll 
write an XSLT sheet to handle that. But I can see that making my XML 
more RDF friendly may allow for greater reuse (of the transform code at 


Murray Spork
Centre for Information Technology Innovation (CITI)
The Redcone Project
Queensland University of Technology, Brisbane, Australia
Phone: +61-7-3864-9488
Email: m.spork@qut.edu.au
Web: http://redcone.gbst.com/
Received on Sunday, 6 October 2002 21:56:48 UTC

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