[oslc-core] Comment on ResourceShape resources

[Ian Green1]

Hi all,

the resource shape spec states that a Shape resource has zero-or-more 
oslc:Property's


an oslc:Property has a (Resource, exactly-one) "rdf:type". 

This is a category error in the RDF model.  The rdf:type is the type of 
the instance, not the type of the RDF predicate which is modelling the 
oslc:Property.

To be concrete - here is an example from the draft:



<oslc:property>
         <oslc:Property>
             <oslc:name>modified</oslc:name>
             <oslc:occurs>exactly-one</oslc:occurs>
             <oslc:namespace rdf:resource="http://purl.org/dc/terms#" />
             <rdf:type rdf:resource="http://purl.org/dc/terms#modified" />
             <oslc:valueType rdf:resource="
http://www.w3.org/2001/XMLSchema#dateTime" />
         </oslc:Property>
     </oslc:property>

This asserts that there is a resource, of rdf:type oslc:Property AND also 
of rdf:type http://purl.org/dc/terms#modified

We don't mean this.   We mean that the oslc:Property is indicated by an 
RDF predicate http://purl.org/dc/terms#modified.

I suggest we change this part of the spec. to use rdf:predicate rather 
than rdf:type.  So the example becomes:

<oslc:property>
         <oslc:Property>
             <oslc:name>modified</oslc:name>
             <oslc:occurs>exactly-one</oslc:occurs>
             <oslc:namespace rdf:resource="http://purl.org/dc/terms#" />
             <rdf:predicate rdf:resource="
http://purl.org/dc/terms#modified" />
             <oslc:valueType rdf:resource="
http://www.w3.org/2001/XMLSchema#dateTime" />
         </oslc:Property>
     </oslc:property>

    -ian

ian.green at uk.ibm.com (Ian Green1/UK/IBM at IBMGB)
Chief Software Architect, Requirements Definition and Management
IBM Rational





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