xml-dev - Schemata are not just constraints [was: "RDF + Topic Maps" = TheFuture]

[Eric van der Vlist <vdv@dyomedea.com>]

Jonathan,

Jonathan Borden wrote:
> 
> Uche,
> 
> >
> > Hmm.  I'm not sure I buy this.  I see RDF Schemas as no more than an arc
> > constraint mechanism.  
> 
> As DTDs and XML Schemata provide syntactic constraints, RDF Schemata provide
> semantic constraints (which for the purposes of this discussion is defined
> as placing constrainsts on arcs and nodes in a directed graph). So it is
> true that RDF Schema provides no more than a constraint mechanism, but I
> offer that this is precisely how ontologies are built. 

Even if sometimes I'd wish they are only this, I think that it's quite
limitative to restrict schemata (either syntaxic or semantic) to a set
of constraints.

Even though validation is their number 1 usage, they convey more
information than being a set of rules to the point of becoming intrusive
when the applications rely on instance and schema merged infosets.

This is a point that I find worrying, since this move toward using
schemata for what they are (schemas) that can lead to locking
applications to specific schema technologies is happening while the
number of alternatives is increasing...

Eric
-- 
------------------------------------------------------------------------
Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
------------------------------------------------------------------------