RE: Potential new issue: PSVI considered harmful

"Dare Obasanjo" <dareo@xxxxxxxxxxxxx> wrote:


> You also link to James Clark's mail to the ietf-xml-use alias where he 
> challenges their 
> recommendation of W3C XML Schema. I refuted about two of his points on XML-
> DEV. The rest are mostly valid criticisms of W3C XML Schemas inability to 
> describe 
> complex co-occurence constraints and the fact that the W3C XML Schema 
> Structures 
> recommendation is written in an inaccessible manner. 
 
This is probably the wrong forum (rather than XML-DEV or ietf-xml-use), but 
which ones do you say you refute?

1) James said that validators don't report as invalid some things that he would 
expect to,
and gave code.

You gave corrected code that would catch it.

Eddie asked why validating a document after it is loaded should give a 
different result than validating when it is loaded. One of the tenants of XSD 
development was that validation needs to be reliable. But that kind of 
inconsistency seems to confirm James' point, rather than refute it.

2) You said that concerns that are relevant to general use don't matter to 
protocols because no-one will read XSD schemas. Yet the IETF draft certainly 
applies to schemas used in RFCs, which people do read.  Perhaps if a schema is 
created dynamically, then Jame's points is not so important, but I think the 
IETF draft is considering the simple use of fixed public schemas more.

Finally, what is this talk about Balkanization?  For fixed public schema 
languages used
to express a document type (for an RFC specifying a protocol) it does not 
matter which Schema language is used.  Every schema language has some 
limitation at which point
natural language is used.   

Cheers
Rick Jelliffe