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Re: Question: SHACL for describing parameterized operations?

From: Holger Knublauch <holger@topquadrant.com>
Date: Tue, 29 Aug 2017 09:26:57 +1000
To: public-rdf-shapes@w3.org
Message-ID: <42a5b57f-3be6-2f2b-5720-a4a6caa6a3a2@topquadrant.com>
Hi Ruben,

it is unclear to me what exactly you are attempting to represent. Below 
you present an outline for a solution but the problem statement isn't 
clear. Could you elaborate a bit?

Note that the SHACL vocabulary (see TTL file) includes the class 
sh:Parameterizable that can be used as superclass of all kinds of 
"templates". For example to state that something takes three arguments, 
you could do

my:Operation rdfs:subClassOf sh:Parameterizable .

ex:findMatchingTriples
     a my:Operation ;
     sh:parameter [
         sh:path ex:subject ;
         sh:order 0 ;
         sh:nodeKind sh:BlankNodeOrIRI ;
     ] ;
     sh:parameter [
         sh:path ex:predicate ;
         sh:order 1 ;
         sh:nodeKind sh:IRI ;
     ] ;
     sh:parameter [
         sh:path ex:object ;
         sh:order 2 ;
     ] ;
     ...

(and then attach whatever you like as other triples to the 
ex:findMatchingTriples - in the case of SHACL-SPARQL there are SPARQL 
queries, in the case of SHACL-JS there are JS snippets).

The above may be on the wrong meta-level, but as I said I don't really 
understand your use case yet.

Regards
Holger



On 28/08/2017 21:41, Ruben Taelman wrote:
> Dear all,
>
> I have a question regarding the potential use of SHACL for a certain 
> use-case,
> and I'm wondering if someone here can help me identify whether or not 
> SHACL is a good solution for this.
>
> I am looking for a vocabulary that can declaratively describe RDF results
> of a certain operation, based on certain parameters.
>
> For example, assume the following operation can evaluate triple 
> pattern queries:
> findMatchingTriples(subject, predicate, object)
>
> As far as I can see, SHACL doesn't provide a way to bind 'variables' 
> to nodes in a shape.
> The closest I have come to describing such a triple pattern operation
> is using the following (invalid) SHACL shape:
>
>   _:shape a sh:NodeShape;
> sh:targetNode _:subject;
> sh:property [
> sh:path _:predicate;
> sh:hasValue _:object.
>           ].
>
> _:subject, _:predicate and _:object refer to the variable parameters 
> of the operation.
>
> I assume I need some kind of abstraction layer above SHACL,
> that basically 'instantiates' SHACL shapes based on certain parameters.
>
> So my question is:
> is such an abstraction already possible in some form, or are there 
> future plans for something like this?
> Or would you suggest using a SPARQL-based vocabulary for this, such as 
> SPIN,
> as I don't really need SHACL's validation and constraint 
> checking-features.
>
> Kind regards,
> Ruben Taelman
Received on Monday, 28 August 2017 23:27:24 UTC

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