RE: Who can implement W3C XML Schema ?
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 > > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://lists.xml.org/ob/adm.pl> > > > > ----------------------------------------------------------------- The xml-dev list is sponsored by XML.org <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://lists.xml.org/ob/adm.pl>
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