Re: rdfdatashapestracker-ISSUE-3 (Shape association): How is a shape associated with a graph?

Looks like we have five options available, four mentioned by Peter and one
by Eric (assigning a shape to an instance).
Are there any other options? I cannot think of any.

I believe that we are not limited to a single option and we can define more
than one shape identification entry points.
Thus, I think that it would be easier if we started to exclude some of the
options based on the use cases.

For instance, I think that #1 and #5 are not easily compatible with S4, S7
& S8.

Best,
Dimitris


On Thu, Dec 4, 2014 at 12:18 AM, Eric Prud'hommeaux <eric@w3.org> wrote:

> * Holger Knublauch <holger@topquadrant.com> [2014-12-03 10:53+1000]
> > If I understand the ticket's purpose correctly, then there are two
> > dimensions
> >
> > a) how to store, reference and share constraint definitions in
> > graphs (Peter addressed that)
> > b) how to instruct an engine so that it knows which checks to perform
> >
> > On b) I believe there is a wide agreement that associating "shapes"
> > with classes makes a lot of sense, and I believe all proposed
> > mechanisms have some vocabulary for that purpose (in SPIN and OWL
> > this is simply relying on the rdf:type arcs). At the same time,
> > there are use cases where this association with classes is not the
> > only mechanism, and some resources need to be checked against
> > additional patterns in specific contexts. In Resource Shapes 2.0
> > this is done (among others) via oslc:valueShape, and it sounds
> > straight-forward to define similar properties that can be submitted
> > as part of a constraint checking request. Resource Shapes 2.0 seems
> > to have oslc:instanceShape and oslc:resourceShape for that purpose.
> > I believe oslc:instanceShape is similar to rdf:type.
>
> [[
> The oslc:instanceShape property is used to link any described resource
> with a shape resource that describes its contents.
> ]] — http://www.w3.org/Submission/2014/SUBM-shapes-20140211/#instanceShape
>
> suggests to me that it connects an instance node to a shape, rather
> than a type to a shape. I propose we use the predicate
> shapes:typeShape until something better comes along.
>
>
> > oslc:resourceShape seems rather specific to the web service
> > architecture, and I am not sure how far the WG will reach in this
> > regard. I would argue the latter could be an OSLC specific extension
> > because it relies on concepts outside of our focus.
> >
> > At this stage I am not sure what is missing to resolve this ticket.
> > The ticket is about collecting all ways a shape can be associated
> > with a graph. Peter has enumerated some. I have written that the
> > rdf:type triples can be used. Who can elaborate on the other
> > mechanisms employed by ShEx and Resource Shapes, and clarify which
> > ones are proposed to be handled by the WG?
>
> For ShEx, we use command line arguments to say "validate node <N> in
> datatype <D> as shape <S>" and "find all shapes for every node in
> dataset <D>".  See <https://github.com/labra/ShExcala/wiki> for an
> example.
>
> If we want properties for this, we can concoct something like
> shapes:startingNode and shapes:startingShape for the former case. For
> the latter, a schema is basically a closed set of shapes so we could
> enumerate shapes to check but maybe it's more reasonable to point to
> the schema.
>
>
> > Thanks,
> > Holger
> >
> >
> > On 12/3/2014 5:58, Peter F. Patel-Schneider wrote:
> > >On 11/18/2014 09:17 AM, RDF Data Shapes Working Group Issue
> > >Tracker wrote:
> > >>rdfdatashapestracker-ISSUE-3 (Shape association): How is a shape
> > >>associated with a graph?
> > >>
> > >>http://www.w3.org/2014/data-shapes/track/issues/3
> > >>
> > >>Raised by: Arnaud Le Hors
> > >>On product:
> > >>
> > >>There has been quite a bit of discussion about how a shape is
> > >>associated with an instance graph. Some technologies rely on a
> > >>type but this isn't accepted by all as sufficient to address all
> > >>use cases. So, what are the ways a shape can be associated with
> > >>a graph?
> > >
> > >
> > >As far as I can see there are only a few potential mechanisms for
> > >associating some constraints with an RDF graph.  (This is separate
> > >from determining which part of the RDF graph the constraint acts
> > >on, by the way.)
> > >
> > >1/ The constraint could be in the graph itself.
> > >
> > >2/ There could be an explicit connection between the graph and a
> > >source for the constraint.  This would work something like
> > >owl:imports, but the source would not have to be an ontology
> > >document.  The connection could also be indirect, e.g., the graph
> > >owl:imports an ontology document which is itself explicitly
> > >connected to a constraint document.
> > >
> > >3/ There could be an implicit connection between the graph and a
> > >source for the constraint.  This could be something like "follow
> > >your nose", i.e., the graph has a node whose IRI can be turned
> > >into a URL that points at a source for the constraint.  This
> > >connection could also be indirect.
> > >
> > >4/ The constraint validation mechanism could take multiple
> > >arguments, one of which is an RDF graph and another of which
> > >contains constraints.  In this mechanism, as opposed to the other
> > >three, there is no way of navigating from the RDF graph to the
> > >constraint.
> > >
> > >
> > >Some proposals naturally or easily work with several of the above
> > >mechanisms.
> > >
> > >
> > >peter
> > >
> > >
> >
> >
>
> --
> -ericP
>
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-- 
Dimitris Kontokostas
Department of Computer Science, University of Leipzig
Research Group: http://aksw.org
Homepage:http://aksw.org/DimitrisKontokostas