W3C home > Mailing lists > Public > www-rdf-comments@w3.org > October to December 2002

RE: Datatype was RE: Confusion about Collections

From: Shelley Powers <shelleyp@burningbird.net>
Date: Tue, 26 Nov 2002 06:03:40 -0600
To: "Patrick Stickler" <patrick.stickler@nokia.com>, <fmanola@mitre.org>
Cc: <www-rdf-comments@w3.org>, "Brian McBride" <bwm@hplb.hpl.hp.com>
Message-ID: <AOEKLHGMHIHGNIBEDMNMEELADFAA.shelleyp@burningbird.net>



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


That's good to know Patrick. I must have missed this in the vocab document.
And one can also assume, then, that people who create instances of a
vocabulary (a specific document) can't override the data type that's shown
in the schema. Is that correct?

Thanks

Shelley
Received on Tuesday, 26 November 2002 07:04:58 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 21 September 2012 14:16:31 GMT