[Mono-list] Issues in XmlSchema.XmlSchemaElement

Atsushi Eno atsushi@ximian.com
Thu, 08 Jan 2004 03:12:19 +0900


> You're not seeing my error because the compile gives up after the first
> error because it throws an exception.  I found and fixed the whitespace
> facet because I discovered it was clearly a problem with the schema and
> a regex expression problem, which may or may not be a problem with the
> schema (more research required).  This revealed the issue I posted.  (If
> anyone cares, I can post the fixed schema or make it available for
> download somewhere).  

Sadly to say, regular expression support is not compliant, currently 
only delegating its process to sys.text.regularexpression. This should 
be fixed by implementing another regular expression processor.

Thanks to the report, I just found and fixed UPA problem, after cutting 
several regexp facets out.

> I'm 100% sure I won't be able to work around the ambiguous problem by
> fixing the schema because of the goofy way the standard works (JDF that
> is) and what goofy things they did in the schema to make it fit; it
> impacts literally thousands of elements.  You see, the CIP4 folks didn't
> have the XML schema standard when they started so they made some
> decisions, like no ordering for child elements, that made it very hard
> to build the schema in the first place.  Furthermore, they didn't want
> to break backwards compatibility even in the early days so they couldn't
> fix the standard to make it more compatible with how XML schema works.

I don't worry about such case. At least we can create modified class 
library code to fit with wrong stuff. Mono is open source, and class 
libraries are under MIT/X11 license. It is really no problem.

However, it is different problem that whether we as a main branch 
maintainer should take care of incorrect stuff, or not.

> doing a better job here.  Anyway, the schema is maintained by a CIP4
> person based on decisions made in a small committee.  I'm going to
> submit the various facet problems and I would expect them to fix those.
> The ambiguity problem is going to be a lot tougher if it does turn out
> to be real and not a bug in Mono.  Committee members will argue that if
> it passes XML Spy, Xerces and Microsoft it should be good enough.

It would be nice to discuss with those people.

Just following up - even Microsoft does good job on XML Schema, their 
implementation is not based on W3C recommendation. For example thay had 
to create more compliant schema collection named XmlSchemaSet in .NET 1.2.

Atsushi Eno