to the main page about the tutorial  THE XML REVOLUTION  -  TECHNOLOGIES FOR THE FUTURE WEB back up next

A small example

Assume we want to create an XML-based language for business cards.

An example document john_doe.xml: 

 <card xmlns="http://businesscard.org">
   <name>John Doe</name>
   <title>CEO, Widget Inc.</title>
   <email>john.doe@widget.com</email>
   <phone>(202) 456-1414</phone>
   <logo url="widget.gif"/>
 </card>

To describe the syntax of our new language, we write a schema business_card.xsd: 

<schema xmlns="http://www.w3.org/2001/XMLSchema"
        xmlns:b="http://businesscard.org"
        targetNamespace="http://businesscard.org">

  <element name="card" type="b:card_type"/>
  <element name="name" type="string"/>
  <element name="title" type="string"/>
  <element name="email" type="string"/>
  <element name="phone" type="string"/>
  <element name="logo" type="b:logo_type"/>

  <complexType name="card_type">
    <sequence>
      <element ref="b:name"/>
      <element ref="b:title"/>
      <element ref="b:email"/>
      <element ref="b:phone" minOccurs="0"/>
      <element ref="b:logo" minOccurs="0"/>
    </sequence>
  </complexType>

  <complexType name="logo_type">
    <attribute name="url" type="anyURI"/>
  </complexType>

</schema>

The XML Schema language is recognized by the namespace http://www.w3.org/2001/XMLSchema.

A document may refer to a schema with the schemaLocation (or the noNamespaceSchemaLocation) attribute: 

 <card xmlns="http://businesscard.org"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://businesscard.org 
                           business_card.xsd">
   ...
 </card>

By inserting this, the author claims that the document is intended to be valid with respect to the schema.

back COPYRIGHT © 2000-2003 ANDERS MØLLER & MICHAEL I. SCHWARTZBACH next