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.
- 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:
- 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.
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.
Reference:
https://help.sap.com/doc/abapdocu_750_index_htm/7.50/en-US/abenabap_overview.htm
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