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RE: XML Schema regex

• From: "Bullard, Claude L (Len)" <clbullar@i...>
• To: robin@k...
• Date: Thu, 16 Aug 2001 09:02:52 -0500

Copying the list to get more feedback on this subject. 
I think we need more sources for XML components.

Some of the difficulty is having multiple ways to 
do things given different sources.  Costello documents 
the best practices.  A simple example is local vs 
global declarations given a legacy relational db 
source.  All of the name collisions out immediately 
and any large db has them.  One can smugly say, well 
namespaces handle that, but that is an axe to cut a 
doorway instead of a well-built frame.  One can use 
local declarations, but then the cleanup one should 
do for the usual reasons that developers may not pay 
attention to the names they use for the same data 
in different table or didn't notice the types.  Globals 
out those quickly.  The good news is that the tools 
like XML Spy that can use ODBC to connect and extract 
a first pass schema work well.  The bad news is the 
use of all local declarations for that, so one has 
to hunt down duplicates.   The next issue is to 
go into the design and start factoring out pieces 
for increased validation power, say creating the common 
regexes and enumerations as types for reuse.  Also, 
you have to sort out the system tables declared by a 
developer for specific-system use (say data-driving the 
GUI) and figure out where these may have invaded the 
common data space (stuff you want to share among systems).

It is a lot of work to build a big schema that has as much 
validation power as possible.  Not doing that means one punts 
back to GUI code thus exposing it in the client, or one keeps 
building maintenance heavy business objects.  Figuring out 
just how much one wants the schema to do or can do is not 
trivial.  Again, I'm a PFE kinda guy but IDEs are really 
the way to go here.   Commonly used components in publicly 
accessible places (no, don't use a URL and just include
them) for free copy and modification are a definite plus 
and each domain vertical has to look at this problem 
with regard to moving on from DTDs to XML Schemas.

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

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

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