DataNucleus supports persisting/retrieving objects to/from Amazon Simple Storage Service (using the datanucleus-json plugin). Simply specify your connection details as follows
datanucleus.ConnectionURL=amazons3:http://s3.amazonaws.com/ datanucleus.ConnectionUserName={Access Key ID} datanucleus.ConnectionPassword={Secret Access Key} datanucleus.cloud.storage.bucket={bucket}
You then create your PMF/EMF as normal and use JDO/JPA as normal.
Things to bear in mind with Amazon S3 usage :-