Re: [xml-dev] XPath 2.0 Best Practice Issue: Graceful Degradation

[John Snelson <john.snelson@oracle.com>]

Costello, Roger L. wrote:
> Michael Kay wrote:
> 
>> You can check whether validation has been performed using "instance
> of"
> 
>> if (airplane instance of schema-element(airplane)) then ... 
> 
> The if-statement is testing to see if the airplane element conforms to
> an XML Schema declaration for the airplane element.  Suppose the test
 > fails.

Wrong. The expression is testing if the element has been validated as 
the XML Schema element declaration named "airplane". The element could 
easily be valid according to that element declaration without having 
been validated by the query that way.

> Is failure to be interpreted as:
> 
> (a) The airplane element did not conform to the airplane element
> declaration in the XML Schema.

No.

> (b) There was no XML Schema against which to validate the airplane
> element.

That would be a static error in the query.

John

-- 
John Snelson, Oracle Corporation            http://snelson.org.uk/john
Berkeley DB XML:        http://www.oracle.com/database/berkeley-db/xml
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