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Re: RDF and XML Schema types

From: m batsis <mbatsis@netsmart.gr>
Date: Wed, 25 Sep 2002 15:56:44 +0300
Message-ID: <3D91B28C.8050009@netsmart.gr>
To: Patrick Stickler <patrick.stickler@nokia.com>
CC: www-rdf-interest@w3.org

Patrick Stickler wrote:

> Though there is also benefit in having a single, compact
> node that alone denotes the datatype value, rather than
> an additional triple defining the type of the literal node.
> 
> But, yes, this form is due to the current
> restriction on literals from being subjects.
> 
> The semantics of 
> 
>    <http://..#integer>"10" 
> 
> is analogous to the presently illegal triple
> 
>    "10" rdf:type <http://..#integer> .

Presently illegal? :-)

This certainly presents some progress to RDF datatyping and I appreciate 
the usefulness of rdf:datatype mechanism. But the mapping from the 
serialization to the graph certainly "feels" weak. IMHO, this is just a 
not-so-good alternative to the URI scheme approaches.


> The reason why "10" can't be a subject is because it is not
> a globally unambiguous name, so you couldn't know *which*
> occurrence of "10" you were talking about. Some other occurrence
> might have some other type, such as xsd:string.

Yes, but using a URI scheme would make it easy to distinguish between 
something like xsd:string#10 and xsd:int#10. All that is needed is a 
standard way to attach a value to a URI that represents a datatype, much 
like <http://..#integer>"10" does (although I don't like the XML 
unfriendly '<, >' characters). And such URIs would not have to be 
interpreted as resources. They would be unique literals (as in 
xs:anyURI), thus eligible as subjects no?

BTW, I have found RDF's behaviour on literals very restrictive, making 
it rather cumbersome in some applications. For example, I wanted to use 
the ICMAUS framework [1] in conjuction with RDF metadata. From an RDF 
point of view, ICMAUS is rather "literal oriented", so I decided to do 
something like

<rdf:Description rdf:ID="someID">
   <my:subject value="Dodge Viper"/>
   <!-- ... -->
</rdf:Description>


while I would like to be able to

<rdf:Description rdf:about="http://myTypes/cars#Dogde%20Viper">
   <!-- ... -->
</rdf:Description>

A standard URI scheme would allow to automatically seperate the datatype 
URI (and infer it's primitive superclass) and the actual value and load 
it in memory as a variable, or store it in a database.


[1] http://www.cognitionresearch.org.uk/sp.htm

Best regards,

Manos
Received on Wednesday, 25 September 2002 08:50:09 GMT

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