In this post, you will learn about ABAP RESTful Application Programming Model (RAP).

  • RAP is an architecture for development of SAP HANA-optimized OData Services for SAP Fiori Applications or Web APIs.
  • It is available in products like SAP BTP ABAP environment, SAP S/4 HANA Cloud and Application Server ABAP 7.56.
  • It is based on CDS and ABAP based custom logic and uses SAPUI5 for user interface

Here is how the architecture looks like –

Before going to the details of each section of RAP, let us also take a look at how the ABAP programming models have evolved. These models may co-exist in some of the systems.

Classic ABAP Programming

  • Freestyle ABAP Code
  • Screen Programming

ABAP Programming Model for SAP Fiori

  • SEGW
  • OData.Publish
  • CDS and CDS based BOPF

ABAP RESTful Application Programming Model

  • Business Service
  • CDS
  • Behavior Definition …

The RAP Model has 3 layers

1. Data Modelling and Behavior

  • The data model is collection of different entities involved in a business scenario, for example airlines, flight routes and flight schedules, and their relationships, for example the parent-child relationship between airline and the flight schedule.
  • RAP uses CDS to define and organize the data model.
  • The behavior describes what can be done with the data model, for example if the data can be created, updated, or deleted.
  • The behavior can be implemented using ABAP

2. Business Service

  • Service Definition is used to define what part of the CDS / Behavior definition will be exposed to next layer
  • Service Binding defines a specific communication protocol such as OData V2 / OData V4

3. Service Consumption 

  • Service can be exposed as a UI Service – This is consumed by SAP Fiori Elements app.
  • An OData service that is exposed as a Web API comes without any UI specific information in the metadata. It is the public interface for any OData client to access the OData service. For example, you can consume a Web API from another OData service.

The RAP model can be used in variety of scenarios to build applications – it can be used to maintain data similar to TMG or to create a Work-list or Master-Detail kind of application.

For our first RAP application we will simply maintain flight booking entries using below steps spanning across all 3 layers.

Data Modelling and Behavior

  1. Create a table
  2. Create root and projection/consumption CDS Entities
  3. Create Metadata Extension
  4. Create Behavior Definition

Business Service

  1. Create Service Definition
  2. Create Service Binding

Service Consumption

  1. Create FIORI Element app

Refer below posts for the Tutorial on all these steps.

  1. ABAP RESTful Application Programming Model [2] – Managed Scenario
  2. ABAP RESTful Application Programming Model [3] – Create Fiori Element App from RAP Service – Managed Scenario
  3. ABAP RESTful Application Programming Model [4] – Unmanaged Scenario Part 1
  4. ABAP RESTful Application Programming Model [5] – Unmanaged Scenario Part 2
  5. ABAP RESTful Application Programming Model [6] – Unmanaged Scenario Part 3
  6. ABAP RESTful Application Programming Model [7] – Create Fiori Element App from RAP Service – Unmanaged Scenario

Visit ABAP RESTful Application Programming Model to explore all articles on ABAP RAP Model.

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