Joshua Allen wrote:
> > that one of the conclusions was that schema validation of RDF was
> quite
> > difficult. I'm sure somebody on this list will correct me, but I am
> under
> > the impression that an RDF schema validator is necessary to validate
> RDF.
> > I don't think XML Schema is up to that task.
> The issue is probably that "validation" can mean different things.  For
> simply validating that the RDF grammar is used correctly (xml
> validation), there is a DTD fragment [1] although this seems to be
> incomplete [2].  There is also an XSD schema [3], which claims to be
> complete for all but the RDF abbreviated syntax.  Validating the RDF
> schema itself is a different story altogether, and really shouldn't be
> the job of DTD or XSD.  I notice that two RDF tools (VRP and GINF) claim
> support for RDF Schema validation.  I couldn't characterize how
> *difficult* this was to implement, but would just point out this is a
> different thing than XML validation.

Yes, I understand the distinction, and the one relies upon the other. You
can do reliable RDF Schema validation if you don't have valid RDF to begin
with. An RDF Schema validator may do both, so perhaps for purposes of this
discussion we could just assume that absent some methodology of attaching
business (or other) semantics to a validated RDF island, it has little use,
whereas *I* can write a DTD module for XHTML adding Dublin Core, and tools
can be written to take advantage of that in short order. I'm at this point
interested in this latter process because it's something I can see the 
bounds of, both in terms of design and level of effort.

The greater project of RDF-in-XHTML relies upon the ability to perform
both types of validation (with perhaps the RDF/XML validation and/or
RDF Schema validation occurring in a separate process -- receiving the
CDATA section DOM node as we've discussed), but *at this point* this is
more a project than I'd want to bite off.


Murray Altheim, SGML/XML Grease Monkey     <mailto:altheim&#64;>
XML Technology Center
Sun Microsystems, 1601 Willow Rd., MS UMPK17-102, Menlo Park, CA 94025

      the wood louse sits on a splinter and sings to the rising sap
      ain't it awful how winter lingers in springtimes lap -- archy

Received on Thursday, 19 April 2001 16:19:05 UTC