JDO Genie is a high performance Java Data Objects (JDO) implementation for relational databases. JDO Genie implements all the required features and most of the optional features of version 1.0 of the specification.JDO Genie is designed for high performance in managed and unmanaged environments and uses leading relational databases for storage (Sybase, Oracle, Postgres, SAP DB, Informix and Microsoft SQL Server are all supported).

JDO Genie is unique among JDO implementations in that it supports distributed PersistenceManagers  PMs do not have to be in the same VM as the JDO Genie server. No need to serialize large graphs of connected value objects between clients and the server.

See http://www.jdogenie.com