In order to view or modify data on a server, REpresentational State Transfer (REST) Architecture requires a client to dispatch requests to the server with HTTP Verb (type of request – GET, POST, PUT and DELETE), header and resource navigation (path) along with optional data in the message body. Based on the received request, the server reverts with a response. The REST approach is efficient, scalable and portable. Its simplicity is an additional asset. Since the server retains no session information and has a bearing on the future sessions, the protocol is deemed Stateless.
SAP Cloud ABAP Environment leverages the RESTful ABAP Programming Model to define its development of SAP Hana-optimized OData services and APIs in an efficient manner. These builds are done for both Cloud and on Premise. There are three layers –
At the Service Consumption Layer, Fiori UI and Web APIs consume OData UI and Web Services to interface with the external world. Any OData client can consume these.
The layer below is Business Service Layer which handles access to data and consumes data to supply services. Service binding defines the communication protocol between request and data while service definition defines the relevant scope for the service. Business Object Projection allows service consumption to project the data per request sent to server.
The layer underneath is Data Modeling and Behavior which deals with the logic and data that fulfil the request as a response.