Persistence strategy "migration"

[Thomas <a9...@unet.univie.ac.at>]

Hi ,
I´m working with an application that uses a flat xml file as persistence 
layer. My duty is to migrate the persistance layer to an XML Database, 
and xindice has been chosen. Well migration may be the wrong terminus 
technicus since in the last meeting it was decided that using factory 
pattern the persistance layer will be chosen between xindice DB and flat 
file (in the future there might be plans to add other DB also).

Browsing the net, i found JDO, hibernate and montag,  but on the first 
informations, I´m not sure if they will fulfill the requirements:

JDO: ( 
http://www.service-architecture.com/database/articles/java_data_objects_jdo.html 
)
The Java Data Objects (JDO) specification is part of the Sun Java 
Community Process. JDO is a Java application program interface (API) for 
transparent persistence. It works with both object and relational 
databases as well as other types of systems. It is designed to also work 
well with EJB and J2EE. 
--> XML Database and flat files may or may not be included in "other 
types of systems"

hibernate: ( http://www.hibernate.org/ )
Hibernate is a powerful, ultra-high performance object/relational 
persistence and query service for Java.
--> XML DB and flat files are not mentioned

Montag:  ( http://montag.sourceforge.net/ )
Montag is a Java Web Services based system for the interaction with 
every Native XML Database that supplies a Java implementation of the 
XML:DB API.
--> apparently this works with XML DB only

Has anyone ever had a similar task and can share his/her experience? 
(links to resources are also welcome)

kind regards
Thomas