2.1 ABAP Programming Language - Overview

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ABAP is a programming language developed by SAP for the development of business applications in the SAP environment. The ABAP Objects component makes object-oriented programming possible.
  1. ABAP on Application Server ABAP
  2. Programming Models
  3. Database Accesses
  4. Special Characteristics
  5. Multilingual Capability
1. ABAP on Application Server ABAP

ABAP is the programming interface of Application Server ABAP (AS ABAP) in SAP NetWeaver. A prerequisite for the use of the ABAP programming language is the installation of an Application Server ABAP. Most of the components of an AS ABAP can be organized in the layers (presentation, application, and database) of a three-tier client-server architecture in accordance with their tasks.
  • The presentation layer is distributed to the workstations of individual users and represents the user interface of an AS ABAP ( SAP GUI or Web browser).
  • The application layer is implemented using one or more application servers. The application layer contains the ABAP runtime environment in which ABAP programs are executed.
  • The database layer consists of a database system in which the central dataset of an AS ABAP is saved.
These three layers are accompanied by the following communication components:

1. RFC Interface

This is the classic functional interface of AS ABAP. A remote function call is a call of a function in a system other than the one in which the calling program is running. Calls are possible between different AS ABAPs or between an AS ABAP and an external system. On AS ABAP, the functions are implemented in function modules. In external systems, specially programmed functions are called whose interface simulates a function module.

2. Internet Communication Manager (ICM)

Internet Communication Manager is a process of AS ABAP that enables AS ABAP to communicate directly with the Internet using HTTP/HTTPS/SMTP. ICM is used to connect Web-based presentation components such as Web Dynpro ABAP and BSP. ICM also enables an AS ABAP to be used both as a client and as a server for Web services. ICM is accessed from within ABAP programs using the classes and interfaces of Internet Communication Framework (ICF).

3. ABAP Channels

ABAP Channels are a framework for event-based communication between application servers and the Internet. ABAP Messaging Channels (AMC) are used to exchange messages between ABAP programs on different application servers. ABAP Push Channels (APC), on the other hand, enable bidirectional communication between AS ABAP and the Internet using the WebSocket protocol or the TCP socket protocol.
The main role of ABAP programs in the application layer is the processing and formatting of data from the database layer and passing this data to the presentation layer or the communication components or receiving data.

2. Programming Models

ABAP supports the following:
  • An object-oriented programming model based on classes and interfaces
  • A procedural programming model based on function modules and subroutines
Both modules offer interoperability.

Note : ABAP Objects is the recommended approach for both new projects and when redesigning existing projects.

3. Database Accesses

One of the fundamental properties of ABAP as a programming language for business applications is that access to database tables is fully integrated into the language.

1. Data Modeling
ABAP data modeling makes it possible to create data models for business applications that have variants on the database:
  • ABAP Dictionary is a persistent repository for data types and their dependencies. They are visible and can be used in all other development objects. ABAP Dictionary manages the database tables, views, and lock objects in a central AS ABAP database.
  • ABAP Core Data Services (ABAP CDS) expand ABAP Dictionary by adding an implementation of the CDS concept for AS ABAP. A cross-platform DDL and DCL make it possible to define CDS views, CDS table functions, and associated CDS roles, plus semantic enrichment.
2. Database Access
Access to data in database tables is fully integrated in ABAP:
  • Open SQL makes it possible to access database objects defined in ABAP Dictionary or ABAP CDS with automatic client handling. This access is cross-platform and integrated into the language. The performance can be optimized using the SAP buffering integrated into the ABAP runtime environment.
  • Native SQL makes platform-specific access to databases possible. Here, ADBC enables general class-based access to databases. AMDP can be used to manage and call database procedures and database functions from the SAP HANA database.
4. Special Characteristics

ABAP is a 4GL language developed specifically for the mass processing of data in business applications. Alongside integrated database access, it offers the following characteristics when compared with elementary languages (where these functions are usually stored in libraries):
  • Internal tables for dynamic storage and processing of mass table data in the working memory.
  • An LUW concept integrated into the ABAP runtime environment, where many users can access the central database simultaneously.
  • The language has an integrated interface to other programming environments using Remote Function Call.
  • The language has an integrated interface to XML.
The integration of these functions into the language is of particular benefit when enabling static checks and for the performance of programs. In return, this means that ABAP also contains considerably more language elements than an elementary programming language.

5. Multilingual Capability

The ABAP programs are made multilingual by extracting language-specific program components from the source code, which are then reloaded when the program executes as specified by the environment. A text environment determines the precise program behavior at runtime, for example the order in which text is sorted.

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