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Re: name that URI was: Re: RDFCore WG: Datatyping documents

From: Jonathan Borden <jborden@mediaone.net>
Date: Tue, 29 Jan 2002 08:47:56 -0500
Message-ID: <003801c1a8cb$91add2c0$0301a8c0@ne.mediaone.net>
To: "Patrick Stickler" <patrick.stickler@nokia.com>, "RDF Interest" <www-rdf-interest@w3.org>
Cc: "RDF Comments" <www-rdf-comments@w3.org>
Patrick Stickler wrote:
> On 2002-01-29 3:46, "ext Jonathan Borden" <jborden@mediaone.net> wrote:

> >
> >
> > perhaps an example makes my point: let's start with the following XML
Schema
> > which has the
> > baseURI=http://example.com/XSD.xsd
> >
> > <xsd:schema xmlns:xsd=http://www.w3.org/2001/XMLSchema
> >               xsd:targetNamespace=http://example.org/foo-schema-ns
> >               xmlns:ns=http://example.org/foo-schema-ns
> >>
> >   <xsd:complexType name="bongo" id="foo">
> >           ...
> >   </xsd:complexType>
> > </xsd:schema>
>
> Well, just a nit, but we're talking about simple types. Complex
> types are not intended to be supported by RDF -- but that doesn't
> invalidate the important parts of your example.
>
> > now the question:
> > what is the URI of the complex type identified by the QName "ns:bongo" ?
> >
> > Hint: according to http://www.w3.org/2001/XMLSchema it is NOT
> >
> > http://example.org/foo-schema-nsbongo
>
> I'm presuming it is http://example.org/foo-schema-ns#bongo, right?

No, see it is more complicated. Strictly speaking there is no URI assigned,
but assume the attribute "id" is of type ID i.e.

<!DOCTYPE xsd:schema "-//..." [
<!ATTLIST xsd:complexType id ID "">
]


Now the _baseURI_ is http://example.com/XSD.xsd

and the ID is composed as a fragment identifier (well now _assume_ that
XPointer is the fragid syntax for application/xml)

so the URI would be:

http://example.com/XSD.xsd#foo

entirely different that what you suspected!

If you don't believe me, simply look at the XML Schemas in the XML Schema
rec.

What I am saying is that XML Schema identifies types by QName (using its own
rules) and that the _base_ simple Type URIs were explicitly created as they
are specified in XML Schema.

The problem is way deeper than '#'

>
> The bottom line is that, it works, we can use it, and
> that's the best we are going to get just now.
>
> Or shall we throw the baby out with the dirty bathwater?

As I said, either use the _predefined_ URIs, and those alone, or else devise
your own URIs. As it stands, the XML Schema mechanism and the RDF mechanism
for assigning QNames and URIs to pieces of XML are _both_ ad hoc and
incompatible. Certainly the XML Schema is more complicated.

You argue to proceed. But proceeding without an architectural solution is
what created this mess in the first place. Sometimes  babies need clean
bathwater, else an epidemic of cholera.

Jonathan
.

Jonathan

Jonathan
Received on Tuesday, 29 January 2002 08:15:27 GMT

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