[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Zvon personal opinion on XML Schema
Hello, although we usually try hard to keep away from personal opinions, the danger of adopting XML Schema as the Standard for XML protocols pressed us to break this rule. Please find below copy of the mail we have sent to: Date: Wed, 5 Jun 2002 10:07:08 +0200 (CEST) From: Miloslav Nic <nicmila@s...> To: ietf-xml-use@i... Subject: XML Schema and IETF protocols Hello, I have been alerted to this group by an xml-dev message quoting: 4.6 Validity and Extensibility and setting XML Schema as the high priority schema format I would consider it a real disaster which already plagues the current W3C standards. I am working for Systinet, one of the top players in Web services area, and as XML Schema is a cornerstone of Web services architecture, many of our developers (including the best ones) have first hand experience with both implementing schemata and with their usage in the "wild". The experience is very frustrating: 1) I am not aware of anyone who would claim that he really understands the specification 2) most developers cannot even read the specification and me and Jirka Jirat are functioning as translators for them and with the very few who can understand we often differ in interpretation which can change several time during discussion 3) the developers in the "wild" are either using very simple constraints correctly or a bit more complex ones in often very peculiar way ( sometimes they are using it incorrectly but often they are using it in a way that it is very difficult to say if their construct is correct or not) 4) Several times we were asked to provide a rather basic constraints for a document, but we were unable to do it ( we think that these constraints cannot be expressed in XML Schema, but you can be never sure) 5) I (Miloslav Nic) tried several times to understand XML Schema but utterly failed. I can of course use the basics and I do agree that the primer is very useful, and I can even without big problems to use and read part II (datatypes) , but I am unable to create mental picture of the specification and after not seeing it for a week or two I start to read it as an novice again. I am founder of Zvon (http://www.zvon.org) and author of many references and tutorials in XML field. I wrote several materials according to W3C specifications, including several which evolved over time and sometimes they were not easy to understand but with some perseverance I finally succeeded. But I had to give with XML Schema, I am afraid I will be never able to pass a beginner stage. (In comparison : I wrote Schematron tutorial a few days after Rick Jelliffe published the original announcement and if I need something from Relax( although thanks to Jiri Jirat our in house expert I am not using it very often) I can figure out what is going on in no time. BTW: I am a coauthor of XML Schema reference ( http://zvon.org/xxl/xmlSchema2001Reference/Output/index.html ), and had to process quite a few schemas in XML Schema (and correct some mistakes in them so I have a proof that I have tried very hard to understand) 6) This mail has been read by Jiri Jirat as well, so this paragraph is authorized : Jiri Jirat authored XML Schema 2001 and Relax NG Tutorial (http://zvon.org/xxl/XMLSchemaTutorial/Output/index.html ) which contains over hundred examples, some of the quite involved one, so he definitively has some expertise in the field. But he still has problems reading the spec and I can quite easily recognize when he needs to find something in it as he sits next to me. Summary: In our personal opinion the adoption of XML Schema for IETF Standards would have very unfortunate effects on the future and it could create tremendous problems for everyone. Miloslav Nic Jiri Jirat -- ****************************************** <firstName> Miloslav </firstName> <surname> Nic </surname> <mail> nicmila@s... </mail> <support> http://www.zvon.org </support>
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