Re: Datatypes

On 21 Aug 2007, at 16:42, Reto Bachmann-Gmür wrote:

> I'm writing an ontology with properties pointing to literals
> representing the following:
> - media types (eg: "application/xhtml+xml")
> - media ranges (eg: "application/*")
> - fully qualified java-class names (eg: "org.example.tools.MyTool")
>
> While I could use xsd:string I think it would be better to use custom
> datatypes to have literals like
> "org.example.tools.MyTool"^^http://example.org/datatypes#javaClass.
>
> My question:
> - Anyone knows a place where such datatypes are already defined?

Not me.

> - Datatypes are typically defined in an XML-schema, is there an  
> ontology
> to do so in RDF?

RDF has pretty limited datatype support in general (both in the spec  
and in the tools...as far as I know). OWL has somewhat better support  
including required support for xsd:string and xsd:integer, plus at  
least defined support for other simple types:
	<http://www.w3.org/TR/2003/WD-owl-semantics-20030203/syntax.html#2>

Deriving URIs for user defined datatypes was left unspecified in  
deference to the XML Schema working group. There's a discussion you  
might find interesting:
	<http://www.w3.org/TR/swbp-xsch-datatypes/>

(Pellet implemented the daml solution.)

OWL 1.1 has a built-in vocabulary for user defined datatypes:

	<http://www.webont.org/owl/1.1/owl_specification.html#4.3>

The rdf form is at the top of:
	<http://www.webont.org/owl/1.1/rdf_mapping.html#2>

> - Is it a good idea to define the datatypes in the same namespace  
> as the
> ontology using them?

I think it's a matter of taste.

Cheers,
Bijan.