W3C home > Mailing lists > Public > xmlschema-dev@w3.org > March 2002

Re: Choice

From: Jeni Tennison <jeni@jenitennison.com>
Date: Sat, 9 Mar 2002 12:56:37 +0000
Message-ID: <166356824316.20020309125637@jenitennison.com>
To: noah_mendelsohn@us.ibm.com
CC: xmlschema-dev@w3.org
Hi Noah,

> Also: Schematron is relatively declarative; my concern was primarily
> with the possible jump to non-declarative languages. It's much
> easier for tools to reason about constraints captured declaratively
> (e.g. in schema facets or derivations, or even Schematron
> assertions) than imperatively (in a Java loop).

Yep. Naturally I was thinking of XSLT as the Turing-complete,
W3C-approved, declarative language of choice.

> The ability to build tools that manipulate and derive information
> from schemas is of key importance. Writing programs that validate
> documents or types may not get us that.

Absolutely. In my mind, there are three primary purposes to schemas -
validation, documentation and tool support. A rule-based approach is
great for validation, and as Schematron shows can be combined with
documentation, but really suffers in terms of providing support for
tools (for helping people author XML, or for analysis prior to
query/transformation for example). I think that the object-oriented
approach of XML Schema provides a big win in this area, and I'm
certainly not advocating that this is lost.

However, I think that at the moment XML Schema's validation power and
flexibility suffers because of its focus on tool support. I am simply
arguing that incorporating a rule-based approach seems a neat way of
correcting that balance.

Anyway, I'm sure that the XML Schema WG are considering all kinds of
changes; just thought a little bit of user input couldn't hurt once in
a while.



Jeni Tennison
Received on Saturday, 9 March 2002 07:56:40 UTC

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