Sunday 4 March 2018

ABAP Programming Language - Overview


ABAP Programming Language - Overview:

ABAP used to be an abbreviation of Allgemeiner BerichtsAufbereitungsProzessor, German for "generic report preparation processor", but was later renamed to the English Advanced Business Application Programming ABAP has a three-tier client-server architecture.

  1. 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).
  2. 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.
  3. 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:

  • 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.

  • 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).

  • 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.

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.

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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