W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2001

Re: heading toward datatyping telecon

From: <Patrick.Stickler@nokia.com>
Date: Mon, 5 Nov 2001 12:11:01 +0200
Message-ID: <2BF0AD29BC31FE46B7887732114404316216B3@trebe003.NOE.Nokia.com>
To: w3c-rdfcore-wg@w3.org


> and I think of the class of the object as identifying its 
> value space, and is independent of its lexical space.
> 
> My mental model.  I can change it its wrong; but I don't think its
uncommon.
> 
> Brian

The problem with this view, though, is that XML Schema
defines a particular lexical space for this value space,
and if applications are getting an RDF literal that has
a type corresponding to e.g. xsd:integer, it should be allowed
IMO to presume that the lexical representation of that
RDF literal conforms to the lexical space defined for
xsd:integer by XML Schema.

To say that one should be able to define things such
as [ rdf:value "0x28"; rdf:type xsd:integer ] and expect
that applications which "support" the XML Schema primitive
and extended data types would be able to eat that is IMO
very unreasonable.

The whole point of XML, RDF, and most W3C standards is to
facilitate interchange, and that means that things are
as consistent, regular, and reliable as possible. Such
standards define a "contract" of sorts between content
producer and content consumer, and deviation from those
standards should be viewed as a breech of contract. No?

I don't see it as useful at all to say that RDF type
qualfications of literals only specify the value space
and not the lexical space. IMO, the lexical space is
just as important, and WRT interchange, could be seen
as the *most* important.

In fact, I'm going even further, to the point of proposing
a mechanism of typed data literal encoding which provides
the actual regular expressions by which an application is
able to validate the lexical form of a given literal per
its defined data type (a more formal specification of the
URV concepts outlined in X-Values).

So, I don't see value space and lexical space as being
separable at all with regards to any encoding of knowledge
such as XML or RDF, and a data type classification that
provides no specification of its lexical realization is
IMO of dubious utility for qualifying literals, as the
very purpose of that data type qualification is to provide
cues to an application about how to parse and use that
value.

Cheers,

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Monday, 5 November 2001 05:11:13 EST

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