- From: RDF Data Shapes Working Group Issue Tracker <sysbot+tracker@w3.org>
- Date: Fri, 23 Oct 2015 05:11:06 +0000
- To: public-data-shapes-wg@w3.org
shapes-ISSUE-104 (Union ranges): Should sh:datatype and sh:class have better support for OR? [SHACL Spec] http://www.w3.org/2014/data-shapes/track/issues/104 Raised by: Holger Knublauch On product: SHACL Spec While playing with SHACL in practice, I noticed a gap in the spec. It is quite common to have properties that can take multiple types of values. sh:text is one example where we hard-coded the pattern rdf:langString OR xsd:string, but a similar variation is xsd:date OR xsd:dateTime. Another example is skos:member, which is skos:Concept OR skos:Collection. schema.org is full of such examples. To express such unions, the current syntax is very verbose and not suitable for static analysis: ex:MyShape sh:property [ sh:predicate ex:property ; sh:maxCount 1 ; ] ; sh:constraint [ sh:or ( [ sh:property [ sh:predicate ex:property ; sh:datatype xsd:string ; ] ] [ sh:property [ sh:predicate ex:property ; sh:datatype rdf:langString ; ] ] ) ] . An option would be to use OWL's unionOf: ex:MyShape sh:property [ sh:predicate ex:property ; sh:maxCount 1 ; sh:datatype [ a owl:Class ; owl:unionOf ( xsd:string rdf:langString ) ] ] . which is much better because it allows us to put everything into a single sh:property node. However, it adds a dependency on OWL, setting wrong expectations about inferencing and all kinds of other unsupported features such as further nested classes, NOT, AND etc, which are usually unnecessary. I believe we should support this syntax: ex:MyShape sh:property [ sh:predicate ex:property ; sh:maxCount 1 ; sh:datatype ( xsd:string rdf:langString ) ] . In this proposal, the values of sh:datatype, sh:directType and sh:class may either be IRIs of classes or an rdf:List of IRIs. The SPARQL queries in the spec would need to be adjusted accordingly. We can delete sh:text instead. I believe this covers a large number of additional use cases while keeping the complexity and implementation burden to a minimum. I believe it is of strategic importance to have a natural way to express schema.org and other common use cases with SHACL.
Received on Friday, 23 October 2015 05:11:09 UTC