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Re: proposal: Structured Datatypes

From: Dan Brickley <danbri@w3.org>
Date: Wed, 6 Nov 2002 23:19:37 -0500 (EST)
To: Jim Hendler <hendler@cs.umd.edu>
cc: Jonathan Borden <jonathan@openhealth.org>, <www-webont-wg@w3.org>
Message-ID: <Pine.LNX.4.30.0211062314070.645-100000@tux.w3.org>

On Wed, 6 Nov 2002, Jim Hendler wrote:

>
> At 10:38 PM -0500 11/6/02, Jonathan Borden wrote:
> >
> >http://www.w3.org/TR/webont-req/#usecase-multimedia
> >
> >it seems to me that structured datatypes fall squarely within the charter of
> >WebOnt. I mean, gasp, if this is something you are not comfortable doing,
> >why would this be an OWL *requirement*
>
> because we didn't think it would be as hard as it is, and we were
> wrong.  Sorry, guess we're not always prescient.
>
> >
> >besides, RDFCore *isn't* dealing with XML dataypes (the ones that have XML
> >in them a.k.a. XML Schema complexType) and as you say this is an issue that
> >we will continue to face over and over until it is properly dealt with. An
> >ideal solution would model an XML Schema particle as an owl:Class, but at
> >the very least I'd like to be able to talk about pieces of XML e.g. say that
> >this is the sameIndividualAs that or that this XML type is the sameClassAs
> >that etc.
>
> yes, they're not talking about
> them because they're hard - and I don't see why they're easier for us
> than for them?

Because WebOnt/OWL can help itself to onto-machinery for talking about the
necessary and sufficient conditions for class membership. RDF/RDFS doesn't
have that; any attempt at shadowing XML structures in RDF/S is imho
somewhat toothless without this. XML Schemas (and DTDs) are all about
picking out classes of documents, and saying (in a special purpose
language) what the rules are that determine whether an infoset instance
falls into some document class or other. Hence 'document type
definitions'. WebOnt might find this topic a rich area to explore, because
OWL allows one to specify class membership criteria. It would be an
interesting exercise to see whether XML syntactic structures (eg. the
document typing rules specified in an XML Schema) can be modelled usefully
in OWL...

On the other hand, it's still a tough problem, and maybe too much work to
fit into current chartered schedule. But then it is also quite hard work
explaining to the Web community how DTDs, XML Schema, RDF Schema and OWL
all fit together. Having this little(?) bridge between XML and RDF might
help make that easier.

Dan


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Received on Wednesday, 6 November 2002 23:19:38 GMT

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