WAX stands for Writing API for XML. It's a new approach to writing XML that

• requires less code than other approaches
• uses less memory than other approaches
(because it outputs XML as each method is called rather than storing it in a DOM-like structure and outputting it later)
• doesn't depend on any Java classes other than standard JDK classes
• is a small library (< 10K)
• requires Java 5 or later (at least for now)
• understands all XML node types
• never outputs XML that isn't well-formed without throwing an exception
• provides extensive error checking
• automatically escapes special characters in text and attribute values when error checking is turned on
• allows all error checking to be turned off for performance
• knows how to associate DTDs, XML Schemas and XSLT stylesheets with the XML it outputs
• is well-suited for writing XML request and response messages for REST-based and SOAP-based services