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RE: Who can implement W3C XML Schema ?

• To: "Doug Ransom" <Doug.Ransom@p...>,<xml-dev@l...>
• Subject: RE: Who can implement W3C XML Schema ?
• From: "Michael Fitzgerald" <mike@w...>
• Date: Wed, 20 Mar 2002 09:07:38 -0800
• Importance: Normal
• In-reply-to: <3C552E6ED5B7DC4F8BF603C030BB70BF3E2D78@H...>

I think RELAX NG has been well regarded because its formal semantics are straightforward.

See http://www.oasis-open.org/committees/relax-ng/spec-20011203.html#semantics

Plus an algorithm for implementing RELAX NG has been published by James Clark, plus several other implementation notes.

See http://thaiopensource.com/relaxng/implement.html

All these things ease the implementation burden considerably.

Mike

-----Original Message-----
From: Doug Ransom [mailto:Doug.Ransom@p...]
Sent: Wednesday, March 20, 2002 8:25 AM
To: xml-dev@l...
Subject: RE:  Who can implement W3C XML Schema ?


As I reviewed this thread I was coming to a similar conclusion, that XML
Schema is the C++ of the XML world.  I don't think I have every used a C++
compiler that got it right.

Perhaps a formal semantics for XML schema would help, or a reference
implementation of XML Schema, or a big reference test suite?

I much prefer schematron to XML Schema as a way to describe and validate XML
documents.





> -----Original Message-----
> From: Dare Obasanjo [mailto:dareo@m...]
> Sent: Wednesday, March 20, 2002 3:39 AM
> To: Paul Spencer; Eric van der Vlist; xml-dev@l...
> Subject: RE:  Who can implement W3C XML Schema ?
> 
> 
> Welcome to the world of design by committee. You can say the 
> exact same things about C99, C++ and SQL92 which have had 3, 
> 5 and 10 years respectively for smart people to implement but 
> still are full of quirks, issues and distinctions between 
> competing implementations.  I'm sure more experienced and 
> knoowledgeable people than me can add more names to this list 
> (perhaps CSS and HTML?) 
> 
> 	-----Original Message----- 
> 	From: Paul Spencer [mailto:paul.spencer@a...] 
> 	Sent: Wed 3/20/2002 3:06 AM 
> 	To: Eric van der Vlist; xml-dev@l... 
> 	Cc: 
> 	Subject: RE:  Who can implement W3C XML Schema ?
> 	
> 	
> 
> 	> I begin to be really worried about the 
> "implementability" of W3C XML
> 	> Schema and I'd like to give an example of what I have already
> 	> experienced several times in the past months (I 
> insist that this is an
> 	> example and almost the general case, *not* an exception).
> 	
> 	I have to agree. I keep coming across schemas that 
> validate in one tool, but
> 	not in another. Sometimes the schema is valid but 
> wrongly described as
> 	invalid, other times it is invalid but the errors are 
> not detected. In one
> 	case, I was asked to look at a schema, and a tool 
> detected an error, but
> 	missed the identical error elsewhere in the same file. 
> I have yet to find
> 	any tool that correctly identifies all errors without 
> also indicating false
> 	errors. And this is on relatively simple schemas.
> 	
> 	We do a lot of schema development and test all schemas 
> against three of the
> 	popular validating tools before delivery. This way we 
> try to catch the
> 	errors and to work around the constructs that generate 
> false errors. But, of
> 	course, many here will be aware of one particular tool 
> that gives different
> 	false errors depending on whether you are looking at 
> the schema in a
> 	graphical view or as text. They don't make it easy for us ...
> 	
> 	The guys that write these tools are not stupid. If they 
> haven't got it right
> 	by now, I worry for the future of XML Schema.
> 	
> 	Paul Spencer
> 	CTO, alphaXML Ltd
> 	Author: Professional XML Design and Implementation (Wrox Press)
> 	Co-author: Beginning XML, Professional XSL (Wrox Press)
> 	XML services for Industry and Government
> 	+44 (0)1491 630053
> 	http://www.alphaxml.com
> 	
> 	
> 	
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  • RE: Who can implement W3C XML Schema ?
    • From: Doug Ransom <Doug.Ransom@p...>

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