Manos Batsis:
> RDF Schema checks the validity of RDF statement semantics; XSD just
> cannot and should not (be enhanced to) do that.
Can you give an example of this? I'm not sure what you mean by "checks the
validity of RDF statement semantics."
> Of course the triple model is serialized in, essentially, XML. Mapping
> what RDF does in vanilla XML+ XSD + enhancements does not make much
> sense in my eyes; XSD validates the structure of an XML document, it
> does not check if a subject of type Person can have a model
> property :-)
This is where we disagree. In my view, XML schemas (should) do far more than
just validation. They provide vital semantics about the class of instances
they define. There is already stuff in XSD that does not relate to
validation (including inheritance, which many have pointed out could be
better handled using type substitution a la Architectural Forms, if all
we're looking for is validation). My strongly held opinion is that many,
many of the XML-related problems that people are struggling with go away if
a framework is available for annotating schemas with semantic
(meta)information.
From there, it is just a no brainer to associate the semantics of an RDF
into this framework in the way I proposed in my last mail (e.g. attaching
Dublin Core semantics to specific element types). You can then generate an
RDF graph from this data, if that floats your boat, but the model I am
proposing is much more approachable because it doesn't force you to work
inside an entirely new model. For instance, it lets you add semantics
incrementally by annotating the schema bit by bit.
> However, if you do manage to do this by injecting custom
> annotations in
> XSD, it would be like embedding RDF in it
Agreed.
> (perhaps ending up with
> something that feels even more awkward and produces even more
> dependencies on the XSD), which does not provide any benefits.
Disagree on all three counts. I don't think it would feel more awkward, it
has nothing to do with XSD (annotations are just associated with the type or
element type name, which could be expressed in RELAX NG or whatever) and it
DOES provide benefits. It's just that the benefits are of a more subtle
nature, as with REST. That was my original point: that RDF is to
Schema+Annotations as SOAP is to REST.
> A nice overview of the differences between XML and RDF is at [1].
>
> [1] http://www.w3.org/DesignIssues/RDF-XML.html
Very clear and well-written, but makes its point based on assumptions that I
don't agree with. Frankly the idea of using schema annotations was never
considered as an alternative to RDF, as far as I can see.
Matt
