[dsdl-discuss] Re: Overlaying schema expressions

At 2004-05-28 08:12 +0900, MURATA Makoto wrote:
>I certainly like the idea of using more than one schema per document.

I think this is natural.

>But, in my understanding, a lot of people think that this is insane.

Then it is time for us to proselytize, and I have a real-world situation
where I will try to bring this up.

>Many people think that schemas provide semantics to documents.

I believe schemas are merely syntax checkers at the level of the presence
of labeled branches in a hierarchical tree.

I believe semantics are implemented solely by applications and how they
wish to interpret the labelled hierarchy of information. The syntax of the
semantics is typically prose. People have tried to convince me that the
use of taxonomies can somehow express semantics formally, but I haven't
grasped this concept yet.

>For them, if a document marries with more than one schema, there will be
>two sets of semantics and thus such bigamous marriage is unacceptable.

Yes, Makoto, I think they do believe that.

I would like to cite literature that might be available on the web that
supports our belief that schemas are merely syntax checkers and that
applications are the semantic engines for markup ... also, are you aware of
articles that contrast this view against the view of contrary opinions?

>PSVI, XPath 2.0, XQuery, XSLT 2.0 are based on this approach.

I did not realize this ... I would only personally ever have used these
technologies to check the syntax of my document ... how are they used by
those who believe they express semantics? By hearing those arguments,
perhaps I can refute them in my own words when I write about my real-world
situation.

>I (and probably most members in this ML) think that a schema is merely for
>sanity checking

Yes, I figured that since this seems to be the prevailing tone in our
face-to-face meetings. In fact, much of my argument as currently
formulated merely points to the work of DSDL supporting multiple
expressions of syntactic constraints.

>and it does not provide any semantics (although schemas
>can be used for generating programs).

Sure, but not for generating *thinking* programs, just skeletal program
beginnings that still need the smarts to be added by a programmer.

>I strongly doubt the future of PSVI, XPath 2, XSLT 2, XQuery, etc. In
>five years (when lots of hype around XML disappear), we will know if
>which approach is correct.

I am really curious now to read more about the basis of this faith in these
technologies that some people have regarding semantics expressed in syntax
... I'm sure it will be good fodder for my justification of using multiple
expressions of syntactic constraints for a single set of semantics.

.......................... Ken

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