RE: [xml-dev] Caught napping!

[Linda Grimaldi <lgrimaldi@neocore.com>]

>We need to develop a process for doing XML datamodelling, so that it
can
>be become a validated science and not just magical art. Then they even
>might begin to teach this methodology at the universities, just as they
>teach relational algebra and modelling.
>capabilites to their existing database systems, making it very easy to
>work with XML data/documents on the storage level.

This is more or less my point.  Our data modelling experience has
generally been
done under the influence, direct or indirect, of a well-understood
relational paradigm.  This is apparent in most schemas out there.  I
fully agree that we need to rigorously develop XML data modelling
practicies, but without XML-based persistence solutions, this would be
nothing more than
an academic exercise.  We also need a standardized XML DB interface (I
know that XML:DB has done some work in this area)- W3C's query language
is a start, but doesn't address update issues, to my knowledge.

One other point about redundant data.  If it can be done with relatively
small footprint cost (each instance taking up only a small delta once
the first instance has been stored), then the redundant
solution is not necessarily as bad as it looks, particularly if the
ability exists to change all instances in a single command from the
application viewpoint. Plus, it gives the flexibility to, for example,
change the customer address for POs that haven't been shipped, while
retaining the address for those that have.  Michael C. made a good point
about not really knowing what RI even means in an XML context- back to
data modelling, again!  Other features that people have grown accustomed
to in an RDBMS- triggers, stored procedures & the like- are more
plumbing issues for the most part than they are necessarily intrinsic to
the XML information model and will be
available as products mature, although, again, we need a standards-based
way of specifying/invoking
these things.

Linda