Fwd: Re: Shapes, Individuals, and Classes - OSLC Motivations

[Forwarding from Arthur - email should have gone to list]


-------- Original Message --------
Subject: 	Re: Shapes, Individuals, and Classes - OSLC Motivations
Date: 	Mon, 17 Nov 2014 17:20:06 -0500
From: 	Arthur Ryman <ryman@ca.ibm.com>
To: 	Holger Knublauch <holger@topquadrant.com>



Holger,

My replies are inline below:
_________________________________________________________
Arthur Ryman
Chief Data Officer
SWG | Rational
905.413.3077 (phone) | 416.939.5063 (cell)
IBM InterConnect 2015


Holger Knublauch <holger@topquadrant.com> wrote on 11/12/2014 07:49:42 PM:

> > Graph 2 is the OSLC Resource Shape for CM. This is linked from the
spec.
> > Its URI is
> > http://open-services.net/pub/Main/CmSpecificationV2Shapes/oslccm-
> change-request-shape.xml
>
> I looked at the triples produced by derefencing ...#ChangeRequest and
see
>
> <http://open-services.net/ns/cm#ChangeRequest>
>          a                 rdfs:Class , owl:Ontology ;
>          rdfs:comment      "The CM Change Request resource" ;
>          rdfs:isDefinedBy  <http://open-services.net/ns/cm#> ;
>          rdfs:label        "ChangeRequest" ;
>          rdfs:seeAlso
> <http://open-services.net/bin/view/Main/
> CmSpecificationV2#Resource_ChangeRequest>
> ;
>          rdfs:subClassOf   rdfs:Resource ;
>          owl:versionInfo   "owl:Ontology added by TopBraid"^^xsd:string
.
>
> Which looks like it uses rdfs:seeAlso to point at an HTML document. I
> don't understand how it points to the .xml file that you mention. So I
> guess there is no formal link and the rdfs:seeAlso is just an
> informative link to humans?

The OSLC specification is an HTML document that is meant to be read by
humans. It contains a hyperlink to the shape resource (
http://open-services.net/pub/Main/CmSpecificationV2Shapes/oslccm-change-request-shape.xml
). The shape resource is an RDF/XML document that is meant to be processed
by tools.

The oslc_cm:ChangeRequest URI is a URI reference that is contained in an
RDFS vocabulary document that contains other RDF term definitions. The
rdfs:seeAlso links point to additional HTML documentation that describes
each term in more detail.

In summary, the OSLC web site is primarily intended for human readers.
However, it does contain some RDF resources, namely RDFS vocabularies and
shapes.

>
>
> > Graphs 3 and 4 are combined into a Resource Shape and are hosted by
the
> > tool that implements and extends OSLC. The OSLC Core spec defines a
> > discovery mechanism that lets you find a variety of information,
including
> > the shapes. Basically, the tool provides a resource that contains
links to
> > a variety of metadata resources, e.g.
http://mytool.example.com/services.
> > See [1].
>
> Looking at the discovery mechanism my first reaction is that this is
> fairly specific to your architecture. Am I wrong here, and do you
> suggest the WG also specifies such a mechanism as part of the W3C
standard?

I think it makes sense for the Linked Data Platform WG to define a
mechanism for associating shapes with an LPD container. Steve Speicher
mentioned this.

>
> >
> > Graph 5 is an instance of a CM resource hosted by the tool, e.g.
> > http://mytool.example.com/resource/42
> >
> > Now suppose you want to create a new instance of a CM resource. This
is
> > done by POSTing an RDF representation to a URL (a creation factory).
You
> > can discover the URL of the creation factory by looking at the service
> > provider metadata resource http://mytool.example.com/services, which
also
> > links to the shape (via oslc:resourceShape).
> >
> > In your proposal, how do you discover the shape of the resource?
>
>  From your Figure 2, I can see that CreationFactory takes both a Shape
> (oslc:resourceShape) and an rdf:type (oslc:resourceType) as its
> arguments. Would it work if you substitute resourceShape with the URL of

> a graph? That graph would extend the globally shared class definition,
e.g.
>
> oslc_cm:ChangeRequest
>      oslc:property [
>          ... any new property for this application
>      ] .
>
> ... and owl:imports the default definition of ex:ChangeRequest to
> inherit the global constraints. The creation factory would operate on
> the union of those graphs (its imports closure). (We can of course use
> another property than owl:imports, if that's a problem).

I am not following your use of "graph". oslc:resourceShape links to an RDF
resource which defines a graph too. oslc:resourceShape is a property. When
used in a triple, its object is expected to be a resource that is of RDF
type oslc:ResourceShape. I believe you are proposing to make the object a
SPIN document. Please confirm.

>
>
> >
> > I believe the difference is that:
> > 1) instead of oslc:ResourceShape resources, you are proposing that the
> > constraints be put in an OWL/SPIN file that has the RDF type URI
> > oslc_cm:ChangeRequest, as a subject node.
>
> Yes, as above.
>
> > 2) instead of oslc:resourceShape, you are proposing to use owl:import
(or
> > maybe another property less specific to OWL)
>
> Yes, you could use oslc:shapeGraph to point at the snippet above.
>
> Please let us know if this would be a viable compromise for your use
cases.

This is promising, but we still need to discuss the OSLC view that there
is a many-to-many relation between shapes and classes.

>
> Thanks
> Holger
>
>