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Re: [xml-dev] RE: Is schemaLocation just a hint in schema import?

From: Rick Jelliffe <rjelliffe@allette.com.au>
Date: Tue, 17 Oct 2006 17:21:32 +1000
Message-ID: <4534847C.6080602@allette.com.au>
To: xml-dev@lists.xml.org
CC: xmlschema-dev@w3.org

C. M. Sperberg-McQueen wrote:
> The Working Group is working as hard as we can to make XML Schema
> 1.1 clearer than 1.0, to fix bugs, and to add useful
> functionality.  Simplification in the form of eliminating
> features has proven to be a very hard sell -- almost everyone
> agrees that there are a lot of features no one would miss, but
> the lists people give don't converge.
I support XSD 1.1 but...

One way to simplify XSD is through layering rather than feature elimination.

* Move key/keyref and integrity constraints to another part
* Move import/include/redefine to another part
* Remove complex type derivation/abstract/substitution/nillability to 
another layer, leaving a smaller-than RELAX NG core language. This may 
entail some simplified syntax, but not as much as some people might 
think, given that complex types are defined by giving the whole content 
model, not just deltas.
* For the part with complex type 
derivation/abstract/substitution/nillability etc, define these are 
functions that notionally reduce the schema into the core language or 
which allow static or dynamic checks on the schema.

These cosmetic changes have the benefit that each part is easier to 
reason about and teach, but also they allow a clear "little XSD" 
profile. It seems to fit in with 
http://www.xml.com/pub/a/2006/09/20/profiling-xml-schema.html too.

That there is no universal agreement on features for a profile is no 
reason not to create at least one profile. When a train is bearing down 
on you, it is not so important that you jump the very best way but that 
you jump at all!

Cheers
Rick Jelliffe
Received on Tuesday, 17 October 2006 07:37:11 GMT

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