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At 16:39 07/12/2001 -0800, Jeff Lowery wrote:
>Speaking of XML that is not:
>Today I've been staring at an industry spec whose XML data model is not
>definable by any schema language that I know of. Validation is currently
>done by what I call "little gray boxes": open-source executables that
>validate the XML document in nice, lengthy, idiosyncratic C++.
>Not being long in XML tooth, I wonder if any of you older hounds might care
>to comment on how commonly such is case in the big, wide, metalanguage
Its positively commonplace. The trick is knowing where to draw the line.
Try and implement everything in declarative grammers is impossible. To
the extent that is possible, it can generate schemas that are less readable
and obvious than VAX 11/780 microcode. There is a sweet spot, its
application and case by case specific. You develop a nose for it but
it takes a long time.
Pragmatists err on the side of little gray boxes because the boxes
are "little" (do something small and do it well), "gray" (plug replaceable
with something else, commodity) and "boxes" (plural - use numerous
little boxes to make an intractable problem tractable via
divide and conquer).
I'll be talking about this and other aspects of the industrialisation
of XML processing at XML 2001 next week