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(unknown charset) Re: do XML Datatypes work for RDF?

From: (unknown charset) Dan Brickley <danbri@w3.org>
Date: Thu, 17 Feb 2000 09:42:42 -0500 (EST)
To: (unknown charset) Stefan Decker <stefan@db.stanford.edu>
cc: (unknown charset) www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.20.0002170934190.21684-100000@tux.w3.org>


On Wed, 16 Feb 2000, Stefan Decker wrote:

> Hi,
> 
> >I suppose we could use
> >         http://www.w3.org/TR/1999/WD-xmlschema-2-19991217/#boolean
> 
> I'am currently using URIs like these for the Protege/RDF implementation.
> So i would be happy with this.
> 
> >for the value of the rdf:range property, but that doesn't work
> >for user-defined derived types.
> Why should i want user-defined types?
> Complex types can be defined using the RDF-mechanisms.

The XML Schema datatypes work has defined a mechanism for user-defined
datatypes. It will be widely used. From an informal look at this, I see
no reason why the data structures (facets etc) for user-defined datatypes
couldn't be reflected into the RDF graph model. This does not mean that
RDF processors would need an understanding of XML Schema syntax.

One good reason for doing the mapping is that RDF-aware systems will want
to import instance data defined using XML Schemas. If we have a common
understanding of how to reflect user-defined XML datatypes into RDF, we
can make the most of this data. If every application handles this
situation differently, we lose information.

Dan

> Using user-defined types based on XML-Schema means, every
> RDF-processor has also to include more sophisticated XML-Schema
> capabilities? Why the effort?
> 
> Do i miss something?
> 
> CU,
>          Stefan
> 
> 
> 
> 
> >The schema spec provides an answer of sorts:
> >
> >"we observe that
> >[XPointer] provides a mechanism which maps well onto our notion of
> >symbol spaces.
> >An fragment identifier of the form
> >#xpointer(schema/element[@name="person"]) will
> >uniquely identify the element declaration with name person, and similar
> >fragment
> >identifiers can obviously be constructed for the other top-level symbol
> >spaces."
> >http://www.w3.org/TR/1999/WD-xmlschema-1-19991217/#ref-schema
> >
> >Is that good enough?
> >
> >
> >The schema specs also include:
> >
> >"RDF Schema
> >      XML Schema: Structures has not yet documented requirements or
> >      dependencies. See [Cambridge Communiqué] for a clarification of the
> >      relationship between the two, which includes requirements arising
> >from web
> >      architecture considerations. "
> >         http://www.w3.org/TR/1999/WD-xmlschema-1-19991217/#intro-relatedWork
> >
> >but I don't see anything in the Cambridge Communiqué that's relevant.
> >
> >The Cambridge Communiqué
> >W3C NOTE 7 October 1999
> >http://www.w3.org/TR/1999/NOTE-schema-arch-19991007
> >
> >
> >--
> >Dan Connolly
> >http://www.w3.org/People/Connolly/
> 
Received on Thursday, 17 February 2000 09:42:43 GMT

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