Service Persistency 

Entity services can be persisted in various data stores. Depending on the application and system landscape, services can be persisted in the following systems:

●     Local relational database

●     Remote systems (for example SAP systems)

●     SAP Knowledge Management (SAP KM)

●     A combination of the above

CAF implements persistency as a combination of session beans on top of Java data objects (JDOs). You should consider, however, that although this information indirectly applies to application services because they use entity services for persistency and data sources.

Local Database

Local persistency is implemented using JDO, which is an API developed by Sun to enable access to any data sources through Java. The JDO implementation addresses relational databases as a data store. The JDO implementation supports all RDBMS (relational database management systems) that are currently supported by SAP.

However, you use the CAF-specific DataAccessService to directly access entity service persistency, not JDOs. A JDO file is also created and contains the relationship between the Java class and database table.

Remote System

Any remote backend system, that is systems whose data is separated from the local CAF database, can be connected to composite application system via external services, which use RFCs or Web services.

To access remote persistency, you assign or map entity service methods and parameters to external service methods and parameters.

SAP Knowledge Management

Documents related to application and entity services are stored in SAP KM. KM-based semantic objects, for example, Document and Folder, are based on the KM framework and are stored exclusively in KM. These objects are included in the core project delivered with CAF.