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- From: Jarle Stabell <jarle.stabell@dokpro.uio.no>
- To: "'xml-dev@ic.ac.uk'" <xml-dev@ic.ac.uk>
- Date: Sun, 24 Jan 1999 17:22:37 +0100
A. G. McDowell wrote:
> There seem to be a large number of languages devoted to listing (for
> instance) the fields that make up a customer order and describing their
> data types. To comprehend a (hypothetical) ecommerce system I might have
> to follow a relational schema for the underlying database, a UML model
> of the application classes and logic, and a schema or DTD for the XML
> used to exchange data with its customers.
>
> Is there any hope of a product that could be used to automatically
> generate some part of this?
I suspect such a product will eventually be available.
The major analysis work required to do a relational schema, object model
and a schema/DTD for XML seems to be the same, finding the
entities/classes/elements/components/concepts (or whatever your favourite
vocabulary/method calls them) and their relations (and some of the
constraints of the relations, multiplicity typically being the most
important)
When doing object models, you have many more choices for
optimalization/design of the implemented structure towards your specific
needs/applications than with the relational model. With XML, you
unfortunately(?) at some point need to choose whether you should implement
a concept as an element or an attribute (most DB/OO design tools forces you
to take this similar decision "too early"), and whether you should
implement/codify a relation using the tree-structure of XML (child
elements), or whether to use IDs and IDREFs type of mechanisms.
I believe the major work in designing DTDs/schemas for XML, relational
schemas and analysis/high level OO class diagrams could use the same
tool/formalism, but that you at some level need to add some extra
information/decisions dependent upon the "output format".
Cheers,
Jarle Stabell
Digital Logikk AS
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