Service Runtime 

Task

Every service accesses and exposes metadata information at runtime. CAF Core provides a metadata service that provides access to the complete metadata of application, entity, and external services and dependent objects. Metadata is stored in the Metadata Model Repository (MMR). During runtime, the metadata is loaded in the server database.

Structure

You should know about:

●     Primary key

●     Semantic key

●     Runtime components

Primary Key

Every service has a unique primary key. The primary key of a service is the global unique identifier (GUID). This maps the object references from Java to the database and allows you to reference objects easily, independent of the persistency. Since GUIDs do not have any business semantics, a secondary index is created, which carries the business semantics.

The primary key for semantic objects (Knowledge Management) is a unique resource identifier (RID).

Semantic Key

A unique semantic key can also be created for an entity service.

Runtime Components

The runtime components of an entity service are shown in the following table.

Component	Description	Location
Session Bean	Local home interface, local interface, bean class	Package com.sap.<application>. besrv.<BusinessEntity>
Value object (persistent object)	JDO persistent capable class. Value object for the entity service and dependent objects	Package com.sap.<application>. besrv.<BusinessEntity>
DB tables	Table description in Java DDIC	Naming: XAP_<UID)>,18 digits
JDO metadata	Files <package>.jdo, <package>.map in the	Package com.sap.<application>. besrv.<BusinessEntity>
RFCs	Source system interfaces for SAP system (if existing BAPIs are not sufficient new ones have to be created)