Re: Are we losing out because of grammars?

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

Joe English wrote:
> 
> XML doesn't need *any* kind of schema language, but lots
> of XML applications benefit greatly from them.  Different
> kinds of applications call for different kinds of schemas;
> those based on tree-local and tree-regular grammars are still
> very useful for "document-centric" applications (HTML, DocBook,
> TEI, etc.).

TREX, following the distinction made by W3C XML Schema between structure
and syntax is also showing that these 2 aspects can be relatively
independent.

Looks like we are going towards 4 different types of XML "schema"
languages to define:

- The structure
- The datatypes
- The rules
- The semantic.

Without mentioning the additions needed if one want to define the
processing associated with these documents.

The recent developments are opening the game and one may hope that we
will be able to choose the best combination for each application.

It should also make the job easier for each of the schema languages that
can keep some aspects out of their scope relying on other languages to
cover them.

For instance, despite many qualities, there are combinations that W3C
XML Schema cannot describe and/or constrain.

The danger if W3C XML Schema was the only language would be that these
combinations would probably become deprecated sooner or later and I
think that this danger is lessened by the availability of other schema
languages that can cover them.

In other words, I feel comfortable to say that each of these languages
is **A** great schema language but would not say for any of them that it
is **THE** great schema language ;=) ...

Eric

> --Joe English
> 
>   jenglish@flightlab.com

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