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   RE: [xml-dev] Who can implement W3C XML Schema ?

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> -----Original Message-----
> From: Jonathan Robie [mailto:jonathan.robie@softwareag.com] 
> Sent: Wednesday, March 20, 2002 6:26 AM
> To: Dare Obasanjo; Paul Spencer; Eric van der Vlist; 
> xml-dev@lists.xml.org
> Subject: RE: [xml-dev] Who can implement W3C XML Schema ?
> I agree: the current implementations are nowhere near 
> compatible enough. If 
> you use XML Schema, and you need it to work compatibly across 
> implementations, be loud - and speak directly to the people who are 
> responsible for solving the problem. Submit concrete examples of 
> incompatibility.

There are for a for doing this already including product newsgroups,
XMLSCHEMA-DEV and the simply reporting bugs to the vendors in question. 

> Call to Arms:
> When you encounter an instance that illustrates compatibility 
> problems, 
> don't let it drop! Instead, do the following:
> 1. Let's figure out which implementations do a particularly 
> good job of 
> implementing XML Schema. If there are one or two that are 
> really good, that 
> would be very useful information, even if there are a bunch 
> that are not 
> good. Let's make compatibility a marketable commodity.

The big selling point of XML is that it allows interoperability which we
who work on the XML technologies at Microsoft are behind 100%. 

Thus I nominate our implementations (XmlValidatingReader in .NET and
MSXML) as validating processors that do a good job of following the XML
Schema recommendation. 

> 2. If the spec is clear and the implementation simply does 
> not implement 
> the spec, let the vendor know the problem, and that 
> compatibility really 
> matters to you. Let's put pressure on the vendors.

This is good advice. Unfortunately many people don't have the time nor
inclination to send bug reports to vendors nor do they know whom to
contact. So far I've taken it upon myself to monitor our newsgroups and
the XMLSCHEMA-DEV list to keep track of issues with our implementations
which on many occassions have turned out to be issues with other
processors that users use to compare results, errors in the primer, or
ambiguities in the recommendation itself. 

> 3. In places where the spec is not clear, or where you as an 
> implementor of 
> XML Schema find it difficult to implement, let's see some 
> email traffic 
> sent to XML Schema. Send your feedback to:
> 	www-xml-schema-comments@w3.org
> I note that there is a spam problem on this comments list. 
> Sigh. XSL and 
> XQuery have fixed their spam problems, I'll send email to the 
> Schema IG 
> suggesting that this is a problem.

I'd suggest bringing the question up on XMLSCHEMA-DEV and only taking
the issue to the comments list if it is clearly an issue with the XML
Schema recommendation. 

I'm actually of the opinion that the issues we've seen with XML Schema
will actually be much worse with XQuery since it a.) uses the XML Schema
type system b.) is overly complex w.r.t type with 3 different casting
constructs, instancof and typeswitch plus a number of tricky type
promotion/casting issues and c.) is missing critical functionality that
many vendors including your employer will probably add as extensions to
the language. 

I will never build only one of anything important. All important systems
have redundant control panels and power supplies. For the same reason I
always carry at least two fully loaded weapons at all times.


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