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Re: proposal: Structured Datatypes

From: Jim Hendler <hendler@cs.umd.edu>
Date: Wed, 6 Nov 2002 15:49:28 -0500
Message-Id: <p05111702b9ef2fa95c21@[12.47.125.13]>
To: "Jonathan Borden" <jonathan@openhealth.org>, <www-webont-wg@w3.org>

Jonathan,
  In our work on dynamic composition of web services using semantics, 
we've really had to face this issue again and again -- we need to go 
from semantic constructs (typically an instance of a class and its 
associated properties) to an XML data structure -- I've become 
convinced this is another one of those problems thta looks easy if 
you're mainly looking at one aspect of it, but when you get into 
details, it looks like a very general purpose mechanism, more complex 
than what you propose, will be both needed and desired.  I also worry 
that this is really something that RDF Core should do (or not do) and 
for us to have a owl-specific solution makes me nervous w/respect to 
the interaction of OWL and RDF (particularly, I think these complex 
types will be instantiated in instances, but the instances typically 
would use the RDF as opposed to OWL MT in general)  I think I agree 
w/Dan that we should Postpone this issue, but I'd sure like to see it 
become one of the foci of any future "semantic web architecture" 
group - because a solution is very necessary if our stuff is going to 
be used in a service context (and probably many others)
  -Jim H.





At 10:29 PM -0500 11/5/02, Jonathan Borden wrote:
>I would like to propose a partial yet relatively simple and interim solution
>to the issue of Structured Datatypes. A full solution would involve
>'grafting' the OWL class hierarchy onto the XML Schema type system i.e. an
>XML Schema type is considered a first class OWL class, and an OWL reasoner
>understands XML Schema type derivation composition etc.
>
>For the interim I propose when rdfs:range restrictions on
>owl:DatatypeProperty classes are URIs that identify XML datatypes (leaving
>alone for the moment the question about how one associates a URI with an XML
>datatype) that the lexical value of the owl:DatatypeProperty be an RDF
>datatype conforming to the syntax of rdf:XMLLiteral and that this fragment
>of XML be valid with respect to the particular XML datatype (e.g. XML Schema
>particle)
>
>For example suppose the XML Schema particle
>
>< xsd:complexType name =" xType " id="xType">
>  < xsd:sequence >
>    < xsd:element name ="a" type =" xsd:int " minOccurs =" 0 " />
>    < xsd:element name ="b" type =" xsd:string " minOccurs =" 0 " />
>  </ xsd:sequence >
></ xsd:complexType >
>
>then (modulo base URIs)
>
><owl:DatatypeProperty rdf:ID="xDTprop">
>     <rdfs:range rdf:resource="#xType"/>
></owl:DatatypeProperty>
>
>and
>
><rdf:Description rdf:ID="foo">
>     <ex:xDTprop rdf:parseType="Literal">
>             <a>123</a>
>             <b>asdaasd</b>
>      </ex:xDTprop>
></rdf:Description>
>
>By this mechanism fragments of XML such as "<a>1234</a><b>asdasd</b>" which
>are valid w.r.t the type "#xType" and are considered individuals/members of
>the class "#xDTprop"
>
>Jonathan


-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
http://www.cs.umd.edu/users/hendler
Received on Wednesday, 6 November 2002 15:49:45 GMT

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