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RE: Are people really using Identity constraints specified in

• To: "Bullard, Claude L (Len)" <len.bullard@i...>
• Subject: RE: Are people really using Identity constraints specified in XML schema?
• From: "Hunsberger, Peter" <Peter.Hunsberger@S...>
• Date: Fri, 20 Aug 2004 10:05:16 -0500
• Cc: <xml-dev@l...>
• Thread-index: AcSGxbViE5ZeocvZQDOQjvR/IzQw+gAAF5yA
• Thread-topic: Are people really using Identity constraints specified in XML schema?

Bullard, Claude L (Len) <len.bullard@i...> writes:

> Aha.  I think the schema is precisely context aware but 
> it cannot change the context it can be aware of.  

Hmm, yes, no, maybe?  Perhaps the writer of the schema is aware of the
context for which they intend the schema to be applicable.  Certainly,
the schema defines validity for some context.  But is that awareness of
(any) context?  It seems to me that awareness of context implies a means
to acknowledge when the schema at hand does not apply?

> As I 
> said to David, it can tell that something is a thing 
> but not the thing.  It can express the intention in 
> some detail but it cannot change the intention.
> 
> In short, it is not a dynamic assembly mechanism 
> because it is not dynamic.
> 
> It is a means to determine the fit of the instance 
> to the expectation of the receiver.   It cannot 
> know that expectation which is why it is referred 
> to as a contract.  If used transactionally, it 
> requires a priori negotiation.

Yes, the context is fixed before hand; therefore, the schema itself is
not context aware; no dynamics means no awareness (circular reasoning
rules).
 
> 
> From: Hunsberger, Peter [mailto:Peter.Hunsberger@S...]
> 
> Wasn't aware that was the objective (local context predominates)...
> 
> However, I think we have a partial answer: schema have no 
> built in mechanism for context awareness or context resolution.
> 
> 

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