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RE: XML Schemas: Best Practices ? Versioning
- From: Tony.Coates@reuters.com
- To: firstname.lastname@example.org
- Date: Thu, 06 Sep 2001 11:39:42 +0100
On 05/09/2001 19:56:47 Michael Brennan wrote:
>I don't think 3 and 4 are reliable. #3 makes the incorrect assumption that
>"instance documents give the name and location of the associated schema". This
>is undoubtedly the prevalent case, but as sound entity resolution mechanisms
>gain more widespread use, I'm inclined to believe there will be less and less
>of this. You cannot assume a consuming application is relying upon the
>"schemaLocation" attribute (or even paying any attention to it). I think
>changing the target namespace is the only reliable approach.
Once again, too much emphasis on the belief that everything should work even if there is no "schemaLocation" given. I really believe that taking this view, which does not seem to be the view of the W3C people I've talked to, will just lead to more complication than is necessary.
>In spite of the complications it poses, I think #2 is the best practice.
>True, instance documents and schemas that include the relevant schema must
>change to reference the new version, but that is often a good thing. You don't
>want those references to indiscriminately change to reference a new schema
>without assurance that there are no incompatibility issues. Indeed, by
>changing the namespace, you can permit concurrent use of different versions of
>a schema, allowing users time to migrate to the new version as compatibility
The same is true if you insist on a versioned "schemaLocation".
Anthony B. Coates
(1) Content Distribution Architect - Project Gazelle
(2) Leader of XML Architecture & Design - Chief Technology Office
Reuters Plc, London.
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