Service Development in the Backend System
Data is retrieved from an SAP Business Suite (backend) system. Both the application logic and metadata are hosted on the SAP Business Suite system. After the service has been developed, you need to activate (register) the service.
To activate the service, register it on the SAP Business Suite system:
Maintain models
Maintain services
You can maintain these settings in IMG activities in the SAP Business Suite system. In transaction SPRO open the SAP Reference IMG and navigate to 
SAP NetWeaver 
SAP Gateway Service Enablement Backend OData Channel Service Development for Backend OData Channel Maintain Models 
and Maintain Services. For more information see Maintaining Models and Services.
To get an overview of the settings the IMG activity SAP NetWeaver SAP Gateway Service Enablement Backend OData Channel Service Development for Backend OData Channel Display Models and Services is provided. Note that this activity is read-only. For more information see Display Models and Services.
After this registration SAP Gateway can expose the corresponding OData services.
Once a service has been defined in the SAP Business Suite system it can be activated on the SAP Gateway system. See Maintain Services.
Under the IMG path SAP NetWeaver SAP Gateway Service Enablement Backend OData Channel Service Development for Backend OData Channel an additional activity OData Channel Generation Tool is provided. For more information, see OData Channel Generation Tool. In addition, an activity is provided to define parallelization of batch queries. For more information, see Define Parallelization of Batch Queries.
Repository Objects
The registration process of OData Channel models and services is unique: In order to allow collecting authorizations per data provider class (DPC) a repository object type is available. This is integrated into transaction SU22. Thus two additional repository object types exist in SAP Gateway. For more information see Roles in the SAP Gateway Landscape.
These repository objects have the following impact:
Models and services shall only be transported via the transport objects.
The external name of a service is derived from the technical name and cannot be freely defined to ensure a GTADIR connection to guarantee unique services. You create service /MYNAMESPACE/MYSERVICE with version 0001 which then results in http://<host>:<port>/sap/opu/odata/mynamespace/MYSERVICE.
The following entities must exist:
The data provider class for the service
The model provider class for all models