Importing Declarations Across Namespaces

XSD Tutorials - Herong's Tutorial Examples - Version 5.10, by Dr. Herong Yang

XSD Tutorials - Herong's Tutorial Examples

∟Linking Multiple Schema Documents Together

∟Importing Declarations Across Namespaces - Examples

This section describes a tutorial example on how to import external namespaces and refer to element declarations from imported namespaces.

A good example of using "import" components is to design a new schema that reuses (or refers to) elements declarations described in the "http://www.w3.org/1999/xhtml" name space.

In the following example, xhtml_import.xsd, declarations of "p", "pre", and "ul" are reused from the imported namespace:

<?xml version="1.0"?>
<xsd:schema
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
   xmlns:xhtml="http://www.w3.org/1999/xhtml">

 <xsd:annotation>
  <xsd:documentation>xhtml_import.xsd
 - Copyright (c) 2013, HerongYang.com, All Rights Reserved.
  </xsd:documentation>
 </xsd:annotation>
 
 <xsd:import namespace="http://www.w3.org/1999/xhtml"
    schemaLocation="xhtml.xsd"/>

 <xsd:element name="book" type="bookType"/>
  
 <xsd:complexType name="bookType">
  <xsd:all>
   <xsd:element name="title" type="xsd:string"/>
   <xsd:element name="author" type="xsd:string"/>
   <xsd:element ref="xhtml:p"/>
   <xsd:element ref="xhtml:pre"/>
   <xsd:element ref="xhtml:ul"/>
  </xsd:all>
 </xsd:complexType>

</xsd:schema>

Notice that:

The "import" component specifies which namespace to import: namespace="http://www.w3.org/1999/xhtml".
The "import" component also specifies where to fetch the schema definitions for this namespace: schemaLocation="xhtml.xsd".
A prefix is declared for this namespace: xmlns:xhtml="http://www.w3.org/1999/xhtml".
The "ref="xhtml:p"" attribute is used to refer to the "p" element declaration from the imported name space.
There is no namespace assigned to the new schema.

In the next section, we will learn how to write an XML document that conforms to a schema that imports declarations from a different namespace.

Last update: 2013.

Table of Contents

About This Book

Introduction to XML Schema

XML Editor and Schema Processor - XMLPad

Java API for XML Processing - JAXP

JAXP - XML Schema (XSD) Validation

Xerces2 Java Parser - Java API of XML Parsers

Using Xerces2 Java API

XML Schema Language - Basics

Introduction of XSD Built-in Datatypes