Dennis Sosnoski has posted the first release candidate of JiBX, yet another open source (BSD license) framework for binding XML data to Java objects using your own class structures. It falls into the custom-binding document camp as opposed to the schema driven binding frameworks like JaxMe and JAXB. Quoting from the JiBX web site,
JiBX is a framework for binding XML data to Java objects. It lets you work with data from XML documents using your own class structures. The JiBX framework handles all the details of converting your data to and from XML based on your instructions. JiBX is designed to perform the translation between internal data structures and XML with very high efficiency, but still allows you a high degree of control over the translation process.
How does it manage this? JiBX uses binding definition documents to define the rules for how your Java objects are converted to or from XML (the binding). At some point after you've compiled your source code into class files you execute the first part of the JiBX framework, the binding compiler. This compiler enhances binary class files produced by the Java compiler, adding code to handle converting instances of the classes to or from XML. After running the binding compiler you can continue the normal steps you take in assembling your application (such as building jar files, etc.; as of Beta 3a you can also skip this as a separate step and instead binding classes directly at runtime, though this approach has some drawbacks).
The second part of the JiBX framework is the binding runtime. The enhanced class files generated by the binding compiler use this runtime component both for actually building objects from an XML input document (called unmarshalling, in data binding terms) and for generating an XML output document from objects (called marshalling). The runtime uses a parser implementing the XMLPull API for handling input documents, but is otherwise self-contained.