Java and XML

The Content

With our header worked out, we now can move on to the actual data content in our XML document. This consists of all the elements, attributes, and textual data within these constructs.

The Root Element

The root element is the highest-level element in the XML document, and must be the first opening tag and the last closing tag within the document. It provides a reference point that enables an XML parser or XML-aware application to recognize a beginning and end to an XML document. In our example, the root element is <JavaXML:Book>:

<JavaXML:Book xmlns:JavaXML="http://www.oreilly.com/catalog/javaxml/" >

  <!-- Content of XML Document -->

</JavaXML:Book>

This tag and its matching closing tag surround all other data content within the XML document. XML specifies that there may only be one root element in a document. In other words, the root element must enclose all other elements within the document. Aside from this requirement, a root element does not differ from any other XML element. It’s important to understand this, because XML documents can reference and include other XML documents. In these cases, the root element of the referenced document becomes an enclosed element in the referring document, and must be handled normally by an XML parser. Defining root elements as standard XML elements without special properties or behavior allows document inclusion to work seamlessly.

Identifying XML with Namespaces

Although we will not delve deeply into XML namespaces here, you should ...