xml data binding and saving "in progress" documents

Hello,

I am working on a java form project where one of the requirements is that the user must be able to save his work "in progress" and be allowed to return later to finish it.

I used JAXB to do the data binding, but the problem is that JAXB doesn't allow "incomplete" object models to be marshalled/unmarshalled.

This has proven to be a huge problem, and we've had to use a really bad hack to address it (namely, "initializing" all the incomplete elements with either blanks, '0', or a default value).

Did anyone run across this problem, and if so, how did you address it? Will using another data binding framework solve it? Castor, XMLBeans? Please help, I'm in a time crunch now.