- From: Pete Hendry <peter.hendry@capeclear.com>
- Date: Thu, 18 Dec 2003 02:43:39 +1300
- To: www-xml-schema-comments@w3.org
Redefine Redefine is a strange beast. It does not map easily to programming languages and the definition of how it is used is, at best, ambiguous. For example, if I have 2 schema definitions, the second of which redefines some of the contents of the first and have the targetNamespace "http://tempuri.org/xsd" and locations http://tempuri.org/original.xsd http://tempuri.org/redefined.xsd and I have in another schema which contains <xsd:import namespace="http://tempuri.org/xsd" schemaLocation="http://tempuri.org/redefined.xsd"/> then there is ambiguity in which schema will be loaded. The schemaLocation is only a hint so a processor that has already loaded the original schema for the given targetNS is free to use it from its cache. It doesn't have to follow the schemaLocation since it thinks it already has the required schema. The opposite could also happen which could lead to unexpected results when an application was written to specifically use the original schema and changes in redefined are not compatible for the application (this could happen where the 2 applications are loaded into the same JVM, perhaps an old version and a new version of the same application). redefined has seen almost no support that I have seen because it is confusing as above and also because it maps poorly to use by programming language tools. I would like to see it dropped from the specification or at least flagged as optional. Pete
Received on Wednesday, 17 December 2003 08:43:44 UTC