Re: XML Schemas: Best Practices

["Roger L. Costello" <costello@mitre.org>]

Hi Folks,

I have summarized our discussions on the issue:

What is Best Practice of checking instance documents for constraints
that are not expressible by XML Schemas? 

The summary may be found at:

    http://www.xfront.com/ExtendingSchemas.html

All comments on the summary write-up are welcome.

Special thanks to Eddie Robertsson for putting together a complete demo
showing how to extend XML Schemas by incorporating Schematron directives
into XML Schema <appinfo> elements.

Although our discussions have been summarized, I feel that this issue is
far from being resolved.  I don't feel like we have come up with a Best
Practice for this issue.  I am not comfortable with any of the options.
Below is an editorial comment that I inserted at the bottom of the
issue's online summary.  Any thoughts on this?

XML Schemas - Strive to be All Powerful?

As XML Schemas completes version 1 and begins work on version 2, the
question comes to mind: "should XML Schemas strive in the next version
to be all powerful?" Programming languages seem to have that goal - to
enable a programmer to express any problem using the language. Perhaps
the goal of version 2 of XML Schemas should be to provide enough
flexibility that any constraint may be expressed.

Alternatively, perhaps XML Schemas should just provide a core set of
constraint expressing mechanisms (as it does today), and let the
marketplace create a technology (technologies?) to supplement XML
Schemas.  Then version 2 of XML Schemas would have few changes from
version 1.

/Roger