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   Re: [xml-dev] Namespaces and XML Schema validation

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The examples you offer are precisely the sort of thing W3C XML Schema
is designed for.  I've provided a complete solution to your first
example below, followed by some notes on how to extend this to yoru
other examples.

<?xml version="1.0">
<a1 xsi:noNamespaceSchemaLocation="a.xsd"
    xmlns:b="http://example.org/b/";
    xmlns:c="http://example.org/c/";>
  <b:b1>This is element B1 from namespace B</b:b1>
  <a2>This is the second element from schema a</a2>
  <c:c1>This element is from namespace c</c:c1>
</a1>

a.xsd:

<xs:schema xmlns:b="http://example.org/b/";
           xmlns:c="http://example.org/c/";>
 <xs:import namespace="http://example.org/b/"; schemaLocation="b.xsd"/>
 <xs:import namespace="http://example.org/c/"; schemaLocation="c.xsd"/>

 <xs:element name="a1">
  <xs:complexType>
   <xs:sequence>
    <xs:element ref="b:b1"/>
    <xs:element name="a2"/>
    <xs:element ref="c:c1"/>
   </xs:sequence>
  </xs:complexType>
 </xs:element>
</xs:schema>

b.xsd
<xs:schema targetNamespace="http://example.org/b/";>
 <xs:element name="b1"/>
</xs:schema>

c.xsd
<xs:schema targetNamespace="http://example.org/c/";>
 <xs:element name="c1"/>
</xs:schema>

Three schema _documents_, one _schema_.

For your second problem, rather than a.xsd importing namespace C, it
would be b.xsd that needed to do this.

For you second problem, each schema document requires some imports,
but the principle is the same.

The core function of the <xs:import> element is to identify
dependencies on schema components (element declarations, type
definitions, etc.) from other namespaces -- references to components
in namespaces other than the targetNamespace fo the schema document or
the xs namespace are not allowed in a schema document without an
import for that namespace.

The source of those components is not rigidly determined -- they may
come from schema documents whose location is given in a schemaLocation
hint in the instance or the import element, or via namespace name
dereference, or the may even be built-in to a processor.

Hope this help.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]




 

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