RE: Schemas Article

["Bullard, Claude L (Len)" <clbullar@ingr.com>]

I have not yet looked into RELAX/TREX deeply enough 
to compare.  Also, I don't have your deep knowledge 
of tree grammars.  Isn't the XQL work creating a 
data model to satisfy this requirement?

Because this also came up on the HumanMarkup list, 
let me ask, do you consider xml-schemas a data modeling 
language or simply a way to define a data structure? 
Does that make a difference?  In other words, is 
it the application or the tool?  Would RDF meet 
your requirements?

Len 
http://www.mp3.com/LenBullard

Ekam sat.h, Vipraah bahudhaa vadanti.
Daamyata. Datta. Dayadhvam.h


-----Original Message-----
From: Murali Mani [mailto:mani@CS.UCLA.EDU]

Interesting. I also tend to believe that OOP is definitely *not* something
which should be there from the beginning. And it is *impossible* to
satisfy everyone with the set of constraints you provide.

Let me ask how important are the following properties in favor of
RELAX NG/RELAX/TREX over xml-schemas ---

a) Query operations are a must for xml-schemas, actually for any data
model. 1-unambiguity for any set of operators other than the usual regular
expression operators (|, ,. *) have *never* been characterized. Without
this characterization, it is impossible to do type inferencing for
operations -- note that local tree grammars etc have been characterized,
but it is the 1-unambiguity that has *never* been characterized.

b) People do data integration -- for merger of companies etc, also for one
project I work on -- a project on sensor networks, where services provided
by sensors are *highly* transitory, and unpredictable. Data integration
benefits *enormously* from closure under union -- actually otherwise, this
problem is so difficult (trying to solve a problem with no solution except
for uncharacterized special cases) that you will *never* be satisfied.