Re: [xml-dev] xml schema

From: "Dare Obasanjo" <>

> From the author's description at http://www.xml.com/pub/au/105 it is 
> noted that he is on the OASIS Technical Committee for a competing schema 
> language, RELAX NG as well as a developer for a RELAX NG tool. 

??? He is also on the W3C XML Schema Working Group, and has developed
an XML Schema tool too (a subset + datatypes).  He is one of the few people 
in the world to have actually tried to implement XML Schemas (*and* RELAX NG, and TREX, and RELAX, and DTDs,  and an experimental Schematron). Which would make him the most experienced implementor of different schema
languages in the world. 

His article[1] is aimed at people who want to know what are the minimal
elements they need to know about without sacrificing constraining power.
And without "driving things to the limit", given that the wheels on a lot of 
WXS products are a little wonky.  

  > I'll let you draw your own conclusions. 
 
He has worked for Sun. Some other guy works for Microsoft, who are 
competitors to Sun and have a big investment in WXS.   What conclusions 
are we allowed to draw from that?  Pfa.

If we look at the X.12 Reference Model for XML Design[2] we see that
they recommend against using the following (which all seem to 
be things that fit in with Kawaguchi-san's approach):
 * abstract types
 * substitution groups
 * redefinition
 * anonymous types
 * user-defined simple types
 * type redefinition
 * type substitution
 * no fixed or default attributes
 * chameleon schemas
 
They go against Kawaguchi's recommendations in
 * prefer local to global
 * prefer types to groups (but they follow his approach of
favouring a single mechanism when there are several ways
to do something, but they choose a different mechanism)

So I don't see that his views should be dismissed summarily.
And certainly not by selectively quoting just some of his affiliations 
and proven technical expertise.  Most of the people on the
RELAX NG WG have been seminal in the XML specifications
at W3C, and in open source software. 

Cheers
Rick Jelliffe
(Not writing on behalf of employer)

[1] http://www.xml.com/pub/a/2001/06/06/schemasimple.html#avoid_complex
[2] http://www.x12.org/x12org/comments/X12Reference_Model_For_XML_Design.pdf