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Re: Datatype was RE: Confusion about Collections

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 26 Nov 2002 09:51:42 +0200
Message-ID: <007701c29520$a8e865d0$4b9316ac@NOE.Nokia.com>
To: "ext Shelley Powers" <shelleyp@burningbird.net>, <fmanola@mitre.org>
Cc: <www-rdf-comments@w3.org>, "Brian McBride" <bwm@hplb.hpl.hp.com>



[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, patrick.stickler@nokia.com]


----- Original Message ----- 
From: "ext Shelley Powers" <shelleyp@burningbird.net>
To: "Shelley Powers" <shelleyp@burningbird.net>; <fmanola@mitre.org>
Cc: <www-rdf-comments@w3.org>
Sent: 25 November, 2002 19:05
Subject: Datatype was RE: Confusion about Collections


> 
> 
> > Also, Frank, a question on dates: I've seen references to
> > multiple documents about what date types are supported. I imagine
> > that we can use RDFS to provide instructions to consumers of our
> > vocabulary as to which date format is being supported. Or do we
> > use rdf:datatype? There's quite a bit of discussion on data
> > types, but it seems disjointed. I can't help thinking that the
> > primer could bring this together.
> >
> > Also question: you all aren't really going to support values of
> > '"1999-08-16"^^xsd:date', are you? No offense, but this horrid.
> > No offense again, but this is absolutely horrid. What's wrong
> > with using RDFS to define the data type, rather than making the
> > value into an intelligent value (ie data type is incorporated
> > into the instance, rather than the vocabulary definition)?
> > Embedding intelligence into values is the worst thing you can do
> > for a data model, regardless of model meta-structure.
> >
> > This is a broader question to group, or a request clarification
> > if I'm reading this wrong. I'm hoping I'm reading this wrong.
> >
> > Shelley
> >
> 
> As a point of clarification on this, it isn't the format that bothers me --
> it's the tying the datatype to instances rather than vocabulary. I know that
> RDF/xml uses rdf:datatype rather than  '"1999-08-16"^^xsd:date', but this
> again attaches the datatype to the instance, rather than the vocabulary. So,
> I could use http://www.w3.org/2001/XMLSchema#date for a date column that has
> data of 199-10-10, and use http://www.w3.org/2001/XMLSchema#integer for
> another instance of the vocabulary (another document), and this means time
> in seconds from a set date. Both are accurate, but neither is compatible.
> 
> See the problems?
> 
> However, if we attach the rdf:datatype to the definition of the vocabulary
> itself rather than any specific document, then the creators of the
> vocabulary can say that this property takes integers representing number of
> seconds since whatever. And all instances (documents) based on the
> vocabulary would be compatible.
> 
> Sorry, I know this is my strong data background talking, but I can see a
> nightmare in the making with this one.
> 
> Shelley

Shelley,

You can specify the datatype range of a property using rdfs:range to
accomplish this. E.g.

   my:dateProperty rdfs:range xsd:date .

And this asserts that all values of my:dateProperty are expected
to be of type xsd:date.

Cheers,

Patrick
Received on Tuesday, 26 November 2002 02:51:45 GMT

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