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Re: 'constraints' on the SKOS Core model

From: Thomas Baker <thomas.baker@bi.fhg.de>
Date: Thu, 27 Jan 2005 15:54:43 +0100
To: "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>
Cc: "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>
Message-ID: <20050127145443.GC1788@Octavius>

On Mon, Jan 24, 2005 at 02:18:56PM -0000, Alistair Miles wrote:
> Tom wrote:
> 7. In sections such as Annotation Constraints, the text says
>    "a concept may have no more than one definition per
>    language".  This seems a touch too prescriptive, as if
>    the Guide were declaring constraints for an XML schema
>    instead of providing guidance in an Open World context.
>    Maybe "should"?
> The idea behind describing 'constraints' was to support stronger validation
> of SKOS Core instance data, where that is required.  A 'constraint' being a
> restriction on the graph structures allowed in instance data which if
> violated would raise a validation error. 

Okay, that confirms what I suspected.

> One of the strongest business cases for XML and XML schema (or DTD etc.) is
> the possibility for strong validation of document structures (which for XML
> equates to data structures).  Although SKOS Core is a semantic web
> application, which implies a commitment to open-world style usage, I believe
> SKOS Core should also be a viable solution for closed world (i.e. enterprise
> internal or business transaction) applications, where strong data validation
> is necessary.  Many people in my experience  find this sort of use case
> (where SKOS Core is essentially a specification of a data exchange format)
> compelling and more relevant to their needs.  SKOS Core competes well with
> pure XML formats here, because of the ease with which the specification can
> be 'extended/refined' (more on this in another email).  
> So anyway, I thought we should support those people who want to do stronger
> validation of instance data by describing constraints on the SKOS Core data
> model.
> However, I think Tom's wording change suggestion is fine.  I.e. we describe
> a set of constraints, which 'should' be implemented, but obviously this is
> RDF so at the end of the day you can do what you want.
> Does this sound sensible?

That sounds sensible.  As additional background, perhaps
it would be helpful to include some of the points you make
above, e.g. along the lines of:

    The SKOS Model consists of RDF properties and classes,
    but many implementers will publish their thesauri or
    knowledge organization systems using DTDs or XML schemas,
    which support the strong validation of data and document
    structures.  For the benefit of implementers who need
    a strongly constrained data exchange format (e.g., for
    enterprise content management or business transactions),
    this specification suggests a few constraints in line
    with common practice for thesauri generally.


Dr. Thomas Baker                        Thomas.Baker@izb.fraunhofer.de
Institutszentrum Schloss Birlinghoven         mobile +49-160-9664-2129
Fraunhofer-Gesellschaft                          work +49-30-8109-9027
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Personal email: thbaker79@alumni.amherst.edu
Received on Thursday, 27 January 2005 14:52:43 UTC

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