Apache ObJectRelationalBridge (OJB) is an Object/Relational mapping tool that allows transparent persistence for Java Objects against relational databases.

OJB supports multiple persistence APIs to provide users with their API of choice:

• A PersistenceBroker API which serves as the OJB persistence kernel. The OTM-, ODMG- and JDO-implementations are built on top of this kernel.
  This API can also be used directly by applications that don't need full fledged object level transactions. (See the Persistence Broker Tutorial for details.)
• A full featured ODMG 3.0 compliant API. (See the ODMG Tutorial for an introduction.)
• A JDO compliant API. We currently provide a plugin to the JDO Reference Implementation (RI). Combining the JDO RI and our plugin provides a JDO 1.0 compliant o/r solution.
  A full JDO implementation is scheduled for OJB 2.0. (See the JDO tutorial for an introduction to the JDO programming model.)
• An Object Transaction Manager (OTM) layer that contains all features that JDO and ODMG have in common. (See the OTM tutorial for details).