Re: shapes-ISSUE-63 (sh:hasShape): Nested shapes: sh:hasShape function versus recursive SPARQL code generation [SHACL Spec]

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One of my concerns with ISSUE-63 is that hasShape may not be implementable
in many SPARQL systems.

peter

On 05/31/2015 10:59 PM, RDF Data Shapes Working Group Issue Tracker wrote:
> shapes-ISSUE-63 (sh:hasShape): Nested shapes: sh:hasShape function versus
> recursive SPARQL code generation [SHACL Spec]
> 
> http://www.w3.org/2014/data-shapes/track/issues/63
> 
> Raised by: Holger Knublauch On product: SHACL Spec
> 
> The SHACL spec currently relies on a SPARQL extension function
> sh:hasShape that can be used to verify that a given resource matches a
> given shape. This function is used in the SPARQL definitions of several
> core templates (e.g. sh:OrConstraint, sh:valueShape) but is also
> generally available for end users to write their own constraints. I
> believe this is very powerful and elegant.
> 
> Peter suggests to not rely on this function, I guess because it requires
> a non-standard extension.
> 
> We need to discuss whether the sh:hasShape function is sufficiently
> problematic that we cannot rely on it, and (if so) precisely define an
> alternative algorithm that can be used instead.
> 
> It may be helpful to hear from implementers whether they believe the
> sh:hasShape function is a problem. Note that even if sh:hasShape is used
> in the definition of the core language, actual implementations may
> optimize its execution to build recursive structures. My assumption is
> that if a database vendor implements SHACL support, then they will
> already have the relevant algorithms implemented, and sh:hasShape is just
> a trivial wrapper for them. Likewise, this function is no problem for
> generic graph APIs such as Jena or Sesame.
> 
> 
> 
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Received on Thursday, 4 June 2015 18:56:04 UTC