ShEx relation to SPIN/OWL

Hi,

This is my first message to this list, so I'll give a brief into.

I'm John Walker and I work at a small (but growing :) company called Semaku [1].
We're working in the area of product information management and publication. We
make extensive use of RDF and related technologies for data integration and all
the other Linked Data goodness.

I'm really interested in the topic of validation of RDF 'graph' data and very
happy this working group is tackling the subject.

Up to now much of our work has been on the data integration side, where
typically we take some XML data source and convert it to RDF. In such a case
normally we'd use XSD / DTD / Relax NG to validate the XML and have some
validated transformation that (hopefully) results in the desired RDF. However
often we see data quality issues that are not necessarily validated by the
schema. Also often quality is a somewhat gray area open for interpretation
rather than a hard pass/fail.

Additionally we see a shift towards using RDF as the data source whereby an
application is directly manipulating the native RDF, so there is no XML/SQL
schema for the data that can be used for validation. In this case something like
ShEx would be extremely useful.

As a n00b to the group I'd be interested to hear some more about the motivation
to introduce a(nother) new syntax for describing these schema. In particular why
not build on existing standards like SPIN and OWL to describe these rules i.e.
what does ShEx offer that SPIN or OWL does not?

Personally I'm a little skeptical to introduce yet *another* syntax without very
good cause as it raises the (already high) bar for adoption of RDF even higher.

Regards,

John

[1] http://semaku.com