RE: Schemas Article

[Murali Mani <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.

<warning>speaking for himself only</warning>

thanks and regards - murali.

On Fri, 8 Jun 2001, Bullard, Claude L (Len) wrote:

> Of those, the one I take to be most
> persuasive is namespace awareness.
> On the other hand, given that is directly
> tieing systemic definitions into the
> information (mixing medium and message)
> it may introduce a pathogen into the
> information itself.  Time will tell.
>
> Yes.  Optimizing for programmers over
> users is usually a big mistake.  It is
> guaranteed to create features explosion.
>
> Modularity should be the next step.
> Oddly, I am seeing people who are not
> part of the XML-Dev community and not
> programmers in general use examples
> and come up to speed on basic Schema
> design very quickly.  So now that
> we have it, I expect it to proliferate.
> Like SGML, people sort out the features
> they need and use them. Some complain
> where those don't meet requirements and
> then there will be a natural fracture.
> I am someone who thinks it a mistake
> to mix schema and OOP design but that
> is just an opinion.   The more we
> hide properties, the less powerful
> markup is for what it does best:
> ensure long lifecycle traits.
>
> Len
> http://www.mp3.com/LenBullard
>
> Ekam sat.h, Vipraah bahudhaa vadanti.
> Daamyata. Datta. Dayadhvam.h
>
>
> -----Original Message-----
> From: Dylan Walsh [mailto:Dylan.Walsh@Kadius.Com]
> >
> >If all TREX does is validate, how will that be
> >any better than a DTD?
>
> 1. Namespace aware
> 2. XML syntax
> 3. AND in content model (from reading the interview)
>
> I've been slightly perplexed by all the negative comments on XML Schema,
> but I've found James Clarks interview
> (http://www.ddj.com/articles/2001/0107/0107e/0107e.htm) to be the most
> persuasive. He makes a strong case for seperating these parts:
> 1. making changes to the infoset (general entities in DTDs, PSVI in XML
> Schema)
> 2. markup validation
> 3. advanced features like OO structures, relational constraints and
> datatyping. In particular this is an area where you can't please all of
> the people, all of the time.
>
> Perhaps XML Schema 1.1 should modularize the standard in the same way
> that XHTML 1.1 does. That said, I suspect that a lot of the negative
> reactions are coming from people who have to implement it. For every
> programmer who uses XML, what percentage have written a parser? It is a
> very small proportion, and I think it will go down better with the
> developer community at large than it has with the core people developing
> the tools.
>
>
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