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RE: what parsers support xml schema

• To: "Murali Mani" <mani@C...>
• Subject: RE: what parsers support xml schema
• From: "Dare Obasanjo" <dareo@m...>
• Date: Fri, 30 Aug 2002 15:03:51 -0700
• Cc: "Maciejewski, Thomas" <Thomas.Maciejewski@l...>,<xml-dev@l...>
• Thread-index: AcJQbyA/YjdBUZJLQaeofwCeBnUrIgAAFdQg
• Thread-topic: what parsers support xml schema

  
> -----Original Message-----
> From: Murali Mani [mailto:mani@C...] 
> Sent: Friday, August 30, 2002 2:49 PM
> To: Dare Obasanjo
> Cc: Maciejewski, Thomas; xml-dev@l...
> 
> This support for named subtyping does not affect in any way 
> the fact that the type inferencing for XQuery is based on 
> regular tree grammars. Type inferencing, regular tree 
> grammars and closure under operations forms the XQuery core, 
> and they go together.

Like I said, the formal semantics is behind the times but [from what
I've seen] the goal of the working group is too make type inferencing
based on named W3C XML Schema types not tree matching. I've given sample
queries in the past on this list that show why named typing makes more
sense than tree matching[0].

Here's the query again, given the following schema

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified"
  targetNamespace="http://www.example.com"
  xmlns:myns="http://www.example.com">

 <xs:element name="foo" type="myns:fooType" />

  <xs:complexType name="fooType" >  
   <xs:element name="bar" minOccurs="3" maxOccurs="6" />
  </xs:complexType>

</xs:schema>

and the query

	schema namespace myns="http://www.example.com"; at
"http:/www.example.com/foo.xsd"
	$foo = <myns:foo>{
document("http://www.example.org/bar.xml")//myns:bar }</myns:foo>
	$foo instance of element of type myns:fooType

What is the result? 

i) NAMED TYPING ANSWER: False, because the $foo variable has type
xs:anyType until validation has been performed on it to confirm that it
matches the schema. 

ii) TREE MATCHING ANSWER: True or False depending on contents of
document at http://www.example.org/bar.xml. Basically the equivalent of
validation occurs implicitly at runtime any time a type needs to be
inferred.  



[0] http://lists.xml.org/archives/xml-dev/200207/msg01024.html  


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