DataNucleus Access Platform 1.0.0 (final) has just been released. Access Platform provides access to a range of datastores for Java applications using JDO/JPA API's. It is fully compliant with JDO1, JDO2, JDO2.1, JPA1, and provides preview features for JDO2.2 and JPA2. It currently supports persistence to RDBMS, db4o, LDAP, XML, Excel, NeoDatis ODB, and JSON. It additionally allows configuration of classes to be persisted using JDO annotations/XML or JPA annotations/XML providing access to both JDO and JPA APIs regardless of which configuration method was chosen, offering a level of flexibility not seen in other persistence tools. Querying of the supported datastores can be performed using JDOQL, JPQL or SQL (dependent on the datastore). By making use of standardised APIs, the process of swapping persistence from one datastore to another is a simple URL change when specifying the datastore.
AccessPlatform is made up of a series of OSGi compliant jars, and can be utilised in J2SE, J2EE, or OSGi container environments. By using OSGi together with eclipse extension-points, DataNucleus is highly extensible so if you wanted to provide support for your own datastore then this would be a relatively simple procedure. DataNucleus Access Platform is licensed under the flexible Apache 2 license.
AccessPlatform is the next generation of the popular Java persistence implementation JPOX