Spring roo - NonRelational DB support

I'm looking for an nonRelational DB implementation (objectDB, or XMLDB) Could somebody recommend some working/tested开发者_运维知识库 sollution, how store objects/XMLdata in a DB?

I recieved additional info, that spring roo stores JDO by itself, using datastore/datanucleus, and no other DB is required.

or 2nd option -> MongoDB + Morphia or 3rd option -> www.db4o.com

For xml documents persistence as a primary requirement, the best option is to use native XML database like Exist. It is using Hierarchical data model afaik and xml document persistence is really simple with it.