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RE: target namespace and namespaces

From: Michael Kay <mike@saxonica.com>
Date: Fri, 3 Dec 2004 16:24:22 -0000
To: "'Dan Vint'" <dvint@dvint.com>, <xmlschema-dev@w3.org>
Message-Id: <E1CaGEL-00072F-00@ukmail1.eechost.net>

> Now I have 1 namespace = 2 different 
> schemas. A data stream that validates against schema 1 with 
> namespace=foo 
> will not validate against schema 2 with namespace=foo. A 
> substantial amount 
> may be legal because of the shared common information but the 
> upper wrapper 
> elements would immediately fail validation.
> 
> Is there anything that considers method 2 a legal design?
> 
> If it isn't illegal is it at least a really poor and 
> troublesome design?
> 

I think there's a real contradiction in the design philosophy here.

On the one hand, XML Schema recognizes that different people may want to
apply different validation criteria to the same document at different stages
of its lifecycle. The sender, for example, may apply stricter rules than the
recipient. So there can be more than one schema that's applicable to a given
document.

On the other hand, XML Schema suggests that knowing the target namespace is
enough information for a schema processor to go and find a schema, with the
schema location being just a hint. If there is more than one schema for a
namespace, then there is no way of telling the processor reliably which one
you want to use.

Let's hope that the WG grasps this particular nettle in its work on
versioning.

Michael Kay
http://www.saxonica.com/
Received on Friday, 3 December 2004 16:24:25 GMT

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