Apache´s persistence tool: OJB

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

* 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 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 OTM tutorial for details).
* A low-level PersistenceBroker API which serves as the OJB persistence kernel. The OTM-, ODMG- and JDO-implementations are build 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).


More features:

# Transparent persistence: Persistent classes don't have to inherit from a persistent base class or to implement an interface.
# Easy use of multiple databases.
# Extremly flexible design with pluggable implementation of most service classes like PersistenceBroker, ObjectCache, SequenceManager, RowReader, ConnectionFactory, ConnectionManager, IndirectionHandler, SQLGenerator, JdbcAccess, ... and so on.
# Comes along with fully functional demo applications running against HSQLDB.