XML Schema

• Data Typing in XML is Weak

<xsd:schema xmlns:xsd="http://www.w3.org/2000/10/XMLSchema">

  <xsd:annotation>
   <xsd:documentation>
    Song schema for XML and Java Example at SD2000 East
    Copyright 2000 Elliotte Rusty Harold. 
   </xsd:documentation>
  </xsd:annotation>
 
  <xsd:element name="SONG" type="songType"/>
 
  <xsd:complexType name="songType" content="elementOnly"">
   <xsd:element name="TITLE"    type="xsd:string"/>
   <xsd:element name="PHOTO"    type="photoType"  
     minOccurs="0" maxOccurs="1"/>
   <xsd:element name="COMPOSER" type="xsd:string" 
     minOccurs="1" maxOccurs="unbounded"/>
   <xsd:element name="PRODUCER" type="xsd:string" 
     minOccurs="0" maxOccurs="unbounded"/>
   <xsd:element ref="publisher" minOccurs="0" maxOccurs="1"/>
   <xsd:element name="LENGTH"   type="xsd:string"/>
   <xsd:element name="YEAR"     type="xsd:string"/>
   <xsd:element name="ARTIST"   type="xsd:string" 
     minOccurs="1" maxOccurs="unbounded"/>
   
   <xsd:attribute name="xmlns"       type="xsd:NMTOKEN" 
    use="fixed" value="http://ibiblio.org/xml/namespace/song"/>
   <xsd:attribute name="xmlns:xlink" type="xsd:NMTOKEN" 
    use="fixed" value="http://www.w3.org/1999/xlink"/>
  </xsd:complexType>
 
  <xsd:complexType name="photoType" content="empty">
   <xsd:attribute name="xlink:type" type="xsd:NMTOKEN" 
    use="fixed" value="simple"/>
   <xsd:attribute name="xlink:show" type="xsd:NMTOKEN" 
    use="fixed" value="embed"/>
   <xsd:attribute name="xlink:href" type="xsd:uri-reference" 
    use="fixed" value="simple"/>
   <xsd:attribute name="ALT"        type="xsd:string"/>
   <xsd:attribute name="WIDTH"      type="xsd:positive-integer"/>
   <xsd:attribute name="HEIGHT"     type="xsd:positive-integer"/>
  </xsd:complexType>
 
  <xsd:element name="PUBLISHER">
    <xsd:complexType base='xsd:string' 
      derivedBy='extension' content="textOnly">
      <xsd:attribute name="xlink:type" type="xsd:NMTOKEN" 
       use="fixed" value="simple"/>
      <xsd:attribute name="xlink:href" type="xsd:uri-reference" />
    </xsd:complexType>
  </xsd:element>
 
</xsd:schema>