Importing Declarations Across Namespaces

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) 2002-2013 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.