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RE: Rules & Grammars

• From: "Bullard, Claude L (Len)" <clbullar@i...>
• To: John Cowan <jcowan@r...>, XML Developers List <xml-dev@x...>
• Date: Wed, 07 Feb 2001 09:25:32 -0600

Opinion:

1.  Hard to keep context.  An element:element just 
overloads the human's ability to stack names.  That 
is, high potential ambiguity when learning how.

2.  Feature rich - it takes awhile to figure out the 
why of complex types, simple types, refs, then abstract 
types, datatypes, and so on.  Until one knows how, 
the tradeoffs are enormous to manage.

3.  Preconditioning - spend a long time acquiring 
skills, for some, DTDs, for others relational views, 
for others object classes.  The XML Schema attempts 
to bridge all of these with a slight leaning toward 
relational views and a definite grounding in DTD 
design.  Confusing. You still need all the other 
bits to apply schemas and they don't work the 
same way in all implementations (Grimaldi's dilemma).

On the other hand, schemas are effective and expressive 
if baroque.  Combined with the rules languages, they are
powerful and reasonably complete.   Now:  what are 
they powerful and complete for?  The mission? 

It seems to me the toughest job is mastering all 
of these, tossing in RDDL, and *selling* this as 
the basis for an interoperable system particularly 
if the requirements for applying them are fuzzy.  

And will we really try to share these across 
agencies?  CALS tried that.  Very hard sell.   

OTOH, the consulting and engineering 
services aspects of enterprise design are very 
lucrative, and it isn't a con.  The problem 
is as tough to do as the tools are to learn.
That's why they call professionals.  HTML 
was easy; how toStartAChat.  XML++ is hard; 
how to design a negotiation.

Failure to deliver the schemas can't be seen 
as a reason for an economy faltering any 
more than getting new grease causes a car 
to lose an ungreased wheel at high speed. 
The problem is mechanics and drivers that 
start the race before the lube.  We can't 
be blamed for that, but it is our job to 
deliver the grease we promised BEFORE 
the race.

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

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


-----Original Message-----
From: John Cowan [mailto:jcowan@r...]

XML Schema, OTOH: why *that* is so hard that I fear I'm unable.
If you pile rule-based stuff onto the already overreaching
Tower of Babel, you might well get a pile of rubble.

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