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Constraints in XML Schema

From: Jan Mendling <mendling@web.de>
Date: Mon, 30 Dec 2002 16:32:33 +0100
Message-Id: <200212301532.gBUFWXO08556@mailgate5.cinetic.de>
To: xmlschema-dev@w3.org

Hello and merry christmas,

I have a design problem with XML Schema. I am in the situation that it would be very appealing to use something like Constraints (beyond the uniqueness-constraints XML Schema offers with Key, Keyref and Unique).

Therefore, I was wondering whether there are attempts being made to integrate a Constraint-Concept into XML Schema (something that we know from SQL in the database area). In my design situation it would be nice to have something like Xpath-Constraints. I am thinking of an Xpath-Statement that must evaluate TRUE in order to validate an instance document against that XML Schema. With such a mechanism it would be easy to build structures and allow only certain content constellations. 

By now, I will probably fix my problem by defining a bunch of simple types which capture these constraints implicitly with the use of regular expressions. A not very elegant solution.

Any hints on constraints in any schema-language will be appreciated. I am looking forward on your commends.

Best regards, 
Jan Mendling

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Received on Monday, 30 December 2002 10:33:05 UTC

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