Validation against multiple schemas

[paulhiggs]

Consider a schema that includes an abstract element form for use by others to extend the schema within the same namespace, such as the following defined by Paul

<!-- main.xsd -->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:paul:main" 
    targetNamespace="urn:paul:main" elementFormDefault="qualified" attributeFormDefault="unqualified">
 <xs:element name="Root">
  <xs:complexType>
   <xs:sequence>
    <xs:element name="Extension" type="myAbstract" minOccurs="0" maxOccurs="unbounded"/>
   </xs:sequence>
  </xs:complexType>
 </xs:element>
 <xs:complexType name="myAbstract" abstract="true">
  <xs:attribute name="extensionName" use="required">
   <xs:simpleType>
    <xs:restriction base="xs:string">
     <xs:pattern value="[A-Za-z0-9]+"/>
    </xs:restriction>
   </xs:simpleType>
  </xs:attribute>
 </xs:complexType>
</xs:schema>

Now Dave defines an extension as

<!-- ext1.xsd -->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:dave:ext" 
    xmlns:main="urn:paul:main" targetNamespace="urn:dave:ext" elementFormDefault="qualified" 
    attributeFormDefault="unqualified">
 <xs:import namespace="urn:paul:main" schemaLocation="main.xsd"/>
 <xs:complexType name="Daves-extn">
  <xs:complexContent>
   <xs:extension base="main:myAbstract">
    <xs:sequence>
     <xs:element name="extensionElement" type="xs:string"/>
    </xs:sequence>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
</xs:schema>

and John defies his extension as

<!-- ext2.xsd -->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:john:ext" 
    xmlns:main="urn:paul:main" targetNamespace="urn:john:ext" elementFormDefault="qualified" 
    attributeFormDefault="unqualified">
 <xs:import namespace="urn:paul:main" schemaLocation="main.xsd"/>
 <xs:complexType name="Johns-extn">
  <xs:complexContent>
   <xs:extension base="main:myAbstract">
    <xs:sequence>
     <xs:element name="anInteger" type="xs:integer"/>
    </xs:sequence>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
</xs:schema>

If an XML instance document is extended by Dave then the following is successful..

<Root xmlns="urn:paul:main" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:ext1="urn:dave:ext"  xsi:schemaLocation="urn:paul:main main.xsd urn:dave:ext ext1.xsd">
<Extension xsi:type="ext1:Daves-extn" extensionName="DAVE001">
 <ext1:extensionElement>An Extension</ext1:extensionElement>
</Extension>
</Root>

doc=libxml.parseXmlString(fs.readFileSync("test.xml"))
doc.validate(libxml.parseXmlString(fs.readFileSync("ext1.xsd"))

If an instance document contains extensions from both Dave and John, such as

<Root xmlns="urn:paul:main" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:ext1="urn:dave:ext"  xmlns:ext2="urn:john:ext" 
    xsi:schemaLocation="urn:paul:main main.xsd urn:dave:ext ext1.xsd urn:john:ext ext2.xsd">

<Extension xsi:type="ext1:Daves-extn" extensionName="DAVE001">
 <ext1:extensionElement>An Extension</ext1:extensionElement>
</Extension>

<Extension xsi:type="ext2:Johns-extn" extensionName="JOHN001">
 <ext2:anInteger>12</ext2:anInteger>
</Extension>

</Root>

then doc.validate() cannot be used, both extension schemas need to be given and evaluated in the validation.

[paulhiggs]

Since this may be related to libxml, I created issue 229 in their repository.

[sdykae]

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