W3C home > Mailing lists > Public > www-rdf-interest@w3.org > January 2001

RE: Formation of RDF terms

From: Jonathan Borden <jborden@mediaone.net>
Date: Mon, 29 Jan 2001 07:55:57 -0500
To: "Dave Beckett" <dave.beckett@bristol.ac.uk>
Cc: "RDF Interest" <www-rdf-interest@w3.org>
Message-ID: <005401c089f2$d293dad0$0201a8c0@ne.mediaone.net>
Dave Beckett wrote:

>
>
> Jonathan said:
> > > > >
> > > > <xsd:unsignedInt rdf:about="http://www.foo.org/someNumber/123">
> > > > 	...
> > > > </xsd:unsignedInt>
> > > >
> [snip for clarity - moved below]
> > > > Ought RDF applications use XML Schema datatypes?
> > >
> > > > What triples ought be generated? Certainly not:
> > > > http://www.w3.org/2000/10/XMLSchemaunsignedInt
> > > >
> > > > N3 already appends a '#' to such namespaces in a bind.
>
> The xsd:unsignedInt concept indeed has the URI above.  There is
> nothing wrong with that.  In the syntax it looks clear as
> xsd:unsignedInt and in the RDF model it is a unique (absolute!) URI
> that can be used as a web-wide identifier.  This may be wierd but it
> is OK.

	True it is a URI, except that it is not the correct URI reference for
xsd:unsignedInt. The URI http://www.w3.org/2000/10/XMLSchema (currently :-)
resolves to an XML Schema, and the fragment identifier #unsignedInt to:

 <simpleType name="unsignedInt" id="unsignedInt">
	 ...
 </simpleType>

so clearly the 'concept' or term 'unsignedInt' has a URI assigned by the XML
Schema spec of:  http://www.w3.org/2000/10/XMLSchema#unsignedInt.

IMHO, it is not reasonable to have RDF and (e.g.) XML Schema assign a
different URI to the same thing.


>
> As I said, the resulting absolute URIs can look odd but still work
> fine.  You said above:
> >  A typedNode qname is not always correctly converted into a URI
> >  according to RDF M&S 1.0.
>
> Can you tell me what isn't correct about the resulting URI:
>   http://www.w3.org/2000/10/XMLSchemaunsignedInt

An URI identifies a resource. The term "unsignedInt" within the XSD
Namespace has a different URI, so the above is a URI, not the correct URI
for the qname xsd:unsignedInt.

>
> Yes - RDF is the model not the funky XML syntax, but somehow people
> forget this.  I've done years of work with RDF and not bothered doing
> anything about the syntax till recently, just using other
> people's parsers.
>
> I've already posted various thoughts on the syntax before including
>   RDF and RDF Schema Concepts
>   http://www.redland.opensource.ac.uk/notes/concepts.html
> since it was difficult to interpret what the syntax concepts meant and
>   A Proposed Interpretation of RDF Containers
>   http://www-uk.hpl.hp.com/people/bwm/rdf/issues/containersyntax/
> with Brian McBride to propose how to interpret containers.

I quite like that actually :-)

>
> I think we might need a note of RDF best practice or errata that
> says:
>
>   In RDF, it is recommended that the XML namespace URIs with # or /.
>   If there is no # or / on the URI, assume that # is present.
>
>
> The relationship between XPointer, XML Base, Xlink, XML Schemas and
> RDF does certainly bear looking at since the RDF syntax we have is
> based on XML and all those technologies are now part of the core XML.
> We may be able to just 'stand on their shoulders' and deal with the
> semantics in the RDF model.  That is a goal I would like.

	For example xml:base, and rdf:about are essentially synonyms.
>
> You mentioned roundtripping XML -> RDF -> XML above; that would need
> some or all of the following:
>   * XML Namespaces URIs and prefixes to be stored in the Model
>   * Literal properties preserved: XML lang, XML space, isWellFormed
>   * XPath of every syntax element recorded
>   * lists of outer top-level elements recorded
>   * order of every element recorded
>   * ... lots more ...
> [ignoring aboutEach, aboutEachPrefix]

	yes, this is difficult and I don't necessarily see this as a goal. The
point I would like to make about this, is that we should see XML as a
*source* for RDF not as a serialization syntax (because purely as a
serialization syntax I might expect to be able to roundtrip -- or to put it
another way: it is really simple to serialize triples or quads). My
particular interest is in the 'RDF interpretation' of XML documents, some
like RSS which have RDF syntax, and others like RDDL which follow the RDF
model.

>
> Let's have fun with some of this at the RDF Interest Group meeting in
> Boston next month.  :-)

:-))

-Jonathan
Received on Monday, 29 January 2001 07:52:56 GMT

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