Java and XML

Last but not least (in this RELAX NG crash course, at least), you can type your data in RELAX NG, using the data element. Here’s the definition of a point type, from the RELAX NG tutorial, for example:

<element name="point" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">   <element name="x">     <data type="double"/>   </element>   <element name="y">     <data type="double"/>   </element> </element>

When you use the string data type (instead of the <text/> tag) for an element, you have to specify the length allowed as well; for this reason, only use the string data type when you have a maximum length in mind:


<element name="email">   <data type="string">     <param name=”maxLength”>127</param>   </data> </element>


That’s not much on RELAX NG, but it’s plenty to help you get started. As mentioned earlier, RELAX NG by Eric van der Vlist (O’Reilly) is available for a more in-depth look at the schema language.