I agree with Mike. Having said that, I believe that UML
is more useful for defining the second sort of data model than
the first. In ISO/IEC JTC 1/SC 32/WG 2 (Metadata),
UML is very heavily used to define models of (and
metamodels for) metadata. These models (and metamodels)
are the second sort of data model, IMHO.
By contrast, in
ISO/IEC JTC 1/SC 32/WG 3 (Database
languages), UML is not used at
all. That's because the SQL data model is
quite close to the relational model of data.
From an application point of view (e.g., a
manufacturing company), the relational
model and/or SQL data model are
"metamodels" that provide standardized
syntax and data structures that the
application uses to define the user's
business data model.
Hope this helps,
Jim
On 2016-09-27 05:41, Michael Kay wrote:
As I look through the XML Schema
specification I see no UML diagrams.
As I look through the GML
specification I see many UML diagrams.
Are UML diagrams not relevant/useful
for data models in the first sense? Are UML diagrams
only relevant/useful for data models in the second
sense?
I suspect that the kind of people who define models like the
XML schema model and the relational model are more comfortable
with maths and legalese English than with pictures. So I think
it tells you more about the psychology of the individuals
concerned than anything else.
Michael Kay
Saxonica
--
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Jim Melton --- Editor of ISO/IEC 9075-* (SQL) Phone: +1.801.942.0144
Chair, ISO/IEC JTC1/SC32 and W3C XML Query WG Fax : +1.801.942.3345
Oracle Corporation Oracle Email: jim dot melton at oracle dot com
1930 Viscounti Drive Alternate email: jim dot melton at acm dot org
Sandy, UT 84093-1063 USA Personal email: SheltieJim at xmission dot com
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= Facts are facts. But any opinions expressed are the opinions =
= only of myself and may or may not reflect the opinions of anybody =
= else with whom I may or may not have discussed the issues at hand. =
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