RE: [xml-dev] Are people really using Identity constraints specified in XML schema?

["Hunsberger, Peter" <Peter.Hunsberger@STJUDE.ORG>]

w3c@drrw.info writes:
> 
> Here's how VAM works in CAM right now.  We have a simple 
> precedence sequence.
> 
> Again - in order to remain sane - and to allow implementers 
> of CAM engines and writers of CAM templates - to do stuff 
> that does not require Teraflops of processing power or 
> excessive tearing of hair out!
> 
> Anyway - the VAM is this - base rules are those in-line rules 
> embedded into structure members, (or included via an included 
> structure).  These are overridden by any rules that match the 
> same XPath target(s) that are declared in the the 
> <BusinessContext> section of the template.  Third - the 
> <ContentReference> section provides default rules (typically 
> retrieved from the central registry, but can be in-lined too) 
> - that provide rules if neither the structure or context 
> section provides any.  Last but not least there is the 
> <DataValidation> section - this is mostly for external calls 
> to webservices - and so again - anything failing these checks 
> will be rejected with an appropriate error - this section is 
> optional though - an intended for backend internal 
> integration needs against the actual data content - rather 
> than structural checks.

I don't really view that as VAM, more like a default fallback mechanism.


<warning type="weak example"/> 

The VAM I want would to something like understand that a researcher can
query on birth date and disease and get back a randomized patient
identifier, but the same query will fail if it contains a geographic
identifier since the population of patients (for the given disease) is
so small that including both restrictions will allow the researcher to
uniquely identify the patient.