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Questions about Validation

From: Ulrich Nicolas LissÚ <u.n.l@gmx.net>
Date: Fri, 12 Dec 2003 17:03:58 +0100
Message-ID: <3FD9E6EE.2010201@gmx.net>
To: www-forms@w3.org

Hi,

I have some questions about validation in XForms from an implementor's 
view. Let me start with some quotations.

* In '4.3.5 The xforms-revalidate Event' the spec states:
...
1. All instance data nodes in all instance elements in the model are 
checked against any specified XML Schema.
2. All instance data nodes in all instance elements in the model are 
checked against any bound model item properties ...
3. The appropriate notification events ... are dispatched to form 
controls ...

* In '4.4.6 The xforms-valid Event' / '4.4.7 The xforms-invalid Event' 
the spec states:
...
This event is dispatched whenever the value of the bound instance data 
node changes, additionally whenever the bound instance data node becomes 
valid / invalid indirectly, through the constraint model item property 
evaluating to true.

So my questions are:

(1) Are the xforms-valid / xforms-invalid events restricted to the 
constraint model item property or has the datatype validity to be taken 
into account here too ? In other words: How is the notion of a model 
item's validity defined exactly ? Is it an aggregate of Schema Datatype 
validity and XForms Constraint satisfaction ? If no, how are the results 
of Schema Datatype validation propagated ? In '6.1.6 The constraint 
Property' the spec says '... When evaluating to XPath false, the 
associated model item is not valid; the converse is not necessarily 
true' and in '6.2.1 Atomic Datatype' it says '... The XForms Processing 
Model applies XML Schema facets as part of the validation process'. I 
read this as a hint for an aggregated validity, but the definition of 
xforms-valid / xforms-invalid seems to contradict that interpretation.

(2) How does a structural Schema validation come into play in XForms ? 
Any external or inline Schema may contain complex type declarations in 
addition to datatype declarations. When it comes to validation, all 
instances have to be validated against any the specified Schema. Again, 
my question is how to handle validation errors here ? Besides the 
problem of propagating Schema validation errors, another problem arises 
here: Such validation errors may affect complex elements for which model 
item properties (and the related events) are not appropriate.

Have I missed something ? Thanks in advance for any advice and 
clarification. Looking forward to your comments,

Uli.
-- 
Ulrich Nicolas LissÚ
Received on Friday, 12 December 2003 11:04:08 GMT

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