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Re: Classroom critique of XML Schema 1.1

From: Michael Kay <mike@saxonica.com>
Date: Sat, 19 Mar 2011 23:34:53 +0000
Message-ID: <4D853D9D.7030003@saxonica.com>
To: "Costello, Roger L." <costello@mitre.org>
CC: "xmlschema-dev@w3.org" <xmlschema-dev@w3.org>

> One student made the following remark after learning of the restrictions on<assert>  and<alternative>  and the inheritable attributes:
>
>     I see no reason for using XML Schema 1.1 since
>     I can do everything (and more) using the combination of
>     XML Schema 1.0 and Schematron. Plus, with
>     Schematron I get friendly, user-defined
>     diagnostic messages, which I don't get from
>     either XML Schema 1.0 or 1.1
>
> How would you respond to that? What does XML Schema 1.1 give that can't already be obtained using XML Schema 1.0 and Schematron?
>

You simply have to look at all the messages that ask "How do I write a 
schema to do X?" and the answers that say "In XSD 1.0 you can't, but in 
XSD 1.1 you can do it like this:...". That's your answer.

Of course XSD 1.1 assertions don't give you any validation capability 
that can't already be achieved using XSD 1.0 + Schematron, or XSD 1.0 + 
XSLT, or XSD 1.0 + Java. But (a) no-one wants to use two technologies if 
one will do, and (b) XSD is not only about validation.

Michael Kay
Saxonica
Received on Saturday, 19 March 2011 23:35:24 GMT

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