ObJectRelationalBridge (OJB) is an Object/Relational mapping tool that allows transparent persistence for Java objects against relational databases. It supports multiple persistence APIs, including JDO, ODMG, and several custom alternatives.
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A JDO prototype and a working sample application were implemented. A new Servlet Implementation allows you to easily deploy the OJB Server as an HTTP-Servlet. Full JTA and JCA integration is in place.