W3C home > Mailing lists > Public > xmlschema-dev@w3.org > January 2003

Re: Opinion of UML-to-XML Schema?

From: Anthony B. Coates <abcoates@londonmarketsystems.com>
Date: Tue, 28 Jan 2003 11:08:53 GMT
To: "Roger L. Costello" <costello@mitre.org>, xmlschema-dev@w3.org
Message-Id: <E18dTeK-000CvT-00@scrabble.freeuk.net>

** Reply to message from "Roger L. Costello" <costello@mitre.org> on Mon, 27
Jan 2003 13:53:29 -0500

> Does anyone have experience with using the UML-to-XML Schema tools? 
> That is, does anyone have experience with using those tools which
> automatically generate XML Schemas from a UML model?  I am interested in
> hearing your experience - good or bad.  /Roger

We tried such tools while I was at Reuters.  They work OK, provided you can be
flexible about what kind of Schema structure you consider acceptable.  However,
for people who like to handcraft Schemas, it is very frustrating to try and get
these tools to produce exactly the same thing you can produce with a good
Schema editor, or a text editor.  That's not a criticism, it's just that people
who come from the XML world are always working with physical models, and can
get very fussy about things like element order.  For data-oriented XML (which
is where UML makes the most sense), my view is that the UML is best used to
construct a logical model of the XML Schema.  That is to say, it should define
which items of data are children of which other items, but decisions like
element order, or whether to use an element or attribute, are probably best
left out of the model and instead configured as settings in whatever converts
UML to XML.

Also, you have the issue that UML structures are not automatically tree
structures, so the fact that you are generating XML typically implies some
constraints on the UML.  Unfortunately, tools don't tend to help enforce those
constraints.  If you really want to just serialise an object model using XML,
then using all of UML is OK, but if you want to use UML as a base for
generating more familiar tree hierarchies, you need to constrain it.

ISO 15022 v2, which defines a repository of financial field and message
definitions, is based on a UML model from which W3C XML Schemas are
automatically generated, and so these are the kinds of Schemas that the
financial world will be doing much of its work with over the coming years.

	Cheers,
		Tony.
====
Anthony B. Coates
London Market Systems Limited
33 Throgmorton Street, London, EC2N 2BR 
http://www.londonmarketsystems.com/
mailto:abcoates@londonmarketsystems.com
Mobile/Cell: +44 (79) 0543 9026
[MDDL Editor (Market Data Definition Language), http://www.mddl.org/]
[FpML Arch WG Member (Financial Products Markup Language), http://www.fpml.org/]
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Received on Tuesday, 28 January 2003 06:21:26 GMT

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