RAD 6.0 supports multiple backends that make multiple deployments inside a single EJB module configurable at runtime. Bottom-up mapping only supports a single backend. A backend can represent different database vendors, or simply alternative mappings and table qualifiers. If multiple backends exist, then the current Backend ID needs to be set in the EJB deployment descriptor editor (when working with EJB 2.x beans). This mapping/deployment will be used at runtime when the JAR is installed on WebSphere Application Server. When deploying EJB 1.1 beans inside an EJB 2.x project, the EJB 1.1 beans are deployed only once, using the first declared database and type.
For 2.x CMPs, you can specify a backend ID for the database type that you are deploying to. The Backend ID determines the persister classes that get loaded at deployment.
Select a database from the drop-down list on the Overview page of the Deployment Descriptor Editor. You can also refresh the Backend ID.