Re: Request for a poll: (was RE: Datatypes vs anarchy)

[Rick Jelliffe <ricko@allette.com.au>]

From: Ronald Bourret <rpbourret@rpbourret.com>

> By the way, XML schemas seem to be most useful for defining XML
> structures -- the mappings that I could figure out to object and
> database schemas get pretty shaky in places. I'm still not sure if this
> is due to the schema language itself or the inherent mismatches between
> XML, objects, and databases. Certainly the problem is not as easy as it
> looks.

Yes. And there is a nice design issue here for the future too:

Perhaps what we need for a schema language is something along the lines of
  <schema>
     <conceptual-model>
    ...
     </conceptual-model>
     <language-binding>
    ...
     </language-binding>
  </schema>

In XML Schemas, we have found all sorts of nice abstractions (components)
for what goes on in a language.  Yet the conceptual modeling people (I think
Robin Cover and Peter Chen might concur) think that the bottom-up approach
is odorous.

That is why, to jump on my hobbey-horse, I don't see that we need more
grammar-based schema languages (not to say that we shouldn't continue to
perfect and mate existing ones).  Instead, we need to start thinking about
what schema languages would be needed to implement the above kind of schema.

Personally, I think that a schema language made from ER for the conceptual
model and a Schematron-like language to do the language binding might be a
nice fit (if Schematron-like languages can be extended to act generatively.)

Cheers
Rick Jelliffe