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From: "W. E. Perry" <wperry@fiduciary.com>
> Validation ... has never successfully translated to the very different
> environment 'on the Web'. XML 1.0 recognized this problem and indeed offered
> the best solution to it in simple well-formedness.
I think this should be "validation on the Web", because at other stages
(validation during system testing, validation during data capture) I don't
think it is true.
Another aspect is that when importing data into a pre-existing application, the
application typically has its own validation. So after the gross error-checking
of WFness, there may only be a fairly narrow range of errors that are not,
in effect, caught. The interesting question for schemas is, what kinds of
errors are these and which validation language can express them?
Following that view, the role of XML validation at the receiving end
is to check constraints that the application does not check (or does
not want to). For example, a bank may adopt some standard DTD
but have its own profile of it, selecting the elements that are relevant.
The function of validation in that case is as a filter: to check that
the incoming document does not have excluded elements or has
the required fields, but not to be concerned with validating the
data that is allowed.
Cheers
Rick Jelliffe
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