Doing More With XML Schemas (part 4) - Old Friends And New

(Page 5 of 7 )

The XML Schema specification also notes the existence of an "attributeFormDefault" attribute of the <xsd:schema> element, which lets schema authors do to attributes what the "elementFormDefault" attribute does for elements - force qualification of each attribute with a namespace prefix. Here's an example that demonstrates how this works:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="http://www.somedomain.com/ns/sw/"
xmlns:sw="http://www.somedomain.com/ns/sw/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" 
attributeFormDefault="qualified">
<!-- define a complex type -->
<xsd:complexType 
name="starWarsEntity">
<xsd:sequence>
<xsd:element name="name" type="xsd:string"/>
<xsd:element 
name="species" type="xsd:string"/>
<xsd:element name="language" type="xsd:string"/>
<xsd:element 
name="home" type="xsd:string"/>
</xsd:sequence>
<xsd:attribute name="episode" 
type="xsd:string" />
</xsd:complexType>
<!-- define the root element 
and its contents -->
<xsd:element name="gallery">
<xsd:complexType>
<xsd:sequence>
<xsd:element 
name="character"
type="sw:starWarsEntity" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

I've introduced a new attribute here for the <character> element - "episode" - which lists the Star Wars episode in which the character first appeared. My use of the "attributeFormDefault" attribute ensures that every occurrence of this attribute in an XML document instance will be prefixed with a namespace - as you can see in the following XML document:

<?xml version="1.0" encoding="UTF-8"?>
<sw:gallery xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:sw="http://www.somedomain.com/ns/sw/"
xsi:schemaLocation="http://www.somedomain.com/ns/sw/starwars.xsd">
<sw:character 
sw:episode="IV">
<sw:name>Luke Skywalker</sw:name>
<sw:species>Human</sw:species>
<sw:language>Basic</sw:language>
<sw:home>Tatooine</sw:home>
</sw:character>
<sw:character 
sw:episode="IV">
<sw:name>Chewbacca</sw:name>
<sw:species>Wookie</sw:species>
<sw:language>Shyriiwook</sw:language>
<sw:home>Kashyyyk</sw:home>
</sw:character>
<sw:character 
sw:episode="VI">
<sw:name>Chief Chirpa</sw:name>
<sw:species>Ewok</sw:species>
<sw:language>Ewok</sw:language>
<sw:home>Endor</sw:home>
</sw:character>
</sw:gallery>

Next: Being Selective >>
 

More XML Articles
More By Harish Kamath, (c) Melonfire

Comments On: Doing More With XML Schemas (part 4)

>>> Be the FIRST to comment on this article!