The idea behind XmlPers is to have a very lightweight database where each object is saved in its own XML file.
The model for XmlPers is that for each persistable class the following information is available:
* Type (e.g. the class name)
* Optional Sub Type (e.g. some type in your class)
* Id
This is not forced on the model itself, but in the DAO. Persisting changes is done by delegating to XmlFilePersister and the DAO must convert the object to a XML Document.