XML Pocket Reference, 3rd Edition

Creating a Simple Schema

While all schemas use the same core parts, there are a number of different structural alternatives and key pieces worth examining before diving into all of the parts. Examine the structure of Example 1-8.

Example 1-8. A simple XML document for definition in a schema

<?xml version="1.0" encoding="us-ascii"?>
<authors>
    <person id="lear">
        <name>Edward Lear</name>
        <nationality>British</nationality>
    </person>
    <person id="asimov">
        <name>Isaac Asimov</name>
        <nationality>American</nationality>
    </person>
    <person id="mysteryperson"/>
</authors>

This document contains an authors element, which itself contains multiple person elements. Each person element has an id attribute and may contain a name and a nationality element. For now, we’ll treat all of the textual content of the elements and attributes as text. One way to define this document is in a schema whose structure mirrors the document, called a “russian doll” schema after the wooden matruschkas; see Example 1-9. The names of the elements being defined are boldfaced to make it easier to read.

Example 1-9. A “russian doll” schema describing the Example 1-8 document

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" >
  <xs:element name="authors">
     <xs:complexType>
        <xs:sequence>
           <xs:element name="person" maxOccurs="unbounded">
              <xs:complexType>
                <xs:sequence minOccurs="0" >
                   <xs:element name="name" type="xs:string" />
                   <xs:element name="nationality" type="xs:
                     string"  />
                </xs:sequence>
                <xs:attribute name="id" type="xs:string" ...