In the previous articles we have discussed about Classical Reports, ALV Grids, Color Formatting and also discussed about meaning of some fields or keyword which are used in programming. But In this article we will discuss about SAP and the Programming Language which we are using in SAP.
What is SAP?
If you read my previous articles, if you are thinking that SAP is a programming language, then you are thinking wrong. SAP is not a Programming Language, it is Business Software Package which is designed to integrate all area of business like HR, Finance, Logistics and other many more areas. SAP provides ERP solutions.
In SAP, there are so many technical modules by which we can develop software applications according to the requirement. The Programming Language (technical module) which we are using to develop applications i.e. ABAP.
What is ABAP?
ABAP stands for Advanced Business Application Programming, a 4GL (4th Generation Language). This programming language is used to make Reports, Module Pool, Function Modules etc. SAP ABAP follows 3-Tier Client/Server Architecture which is show in following picture:-
Presentation Server: The presentation server is actually a program named sapgui.exe. It is usually installed on a user’s workstation. To start it, the user double-clicks on an icon on the desktop or chooses a menu path. When started, the presentation server displays the R/3 menus within a window. This window is commonly known as the SAPGUI, or the user interface (or simply, the interface). The interface accepts input from the user in the form of keystrokes, mouse-clicks, and function keys, and sends these requests to the application server to be processed. The application server sends the results back to the SAPGUI which then formats the output for display to the user.
Application Server: An application server is a set of executable that collectively interpret the ABAP/4 programs and manage the input and output for them. When an application server is started, these executable all start at the same time. When an application server is stopped, they all shut down together. The number of processes that start up when you bring up the application server is defined in a single configuration file called the application server profile.
Each application server has a profile that specifies its characteristics when it starts up and while it is running. For example, an application sever profile specifies:
- Number of processes and their types
- Amount of memory each process may use
- Length of time a user is inactive before being automatically logged off
The application server exists to interpret ABAP/4 programs, and they only run there-the programs do not run on the presentation server. An ABAP/4 program can start an executable on the presentation server, but an ABAP/4 program cannot execute there.
Database Server: The database server is a set of executable that accept database requests from the application server. These requests are passed on to the RDBMS (Relation Database Management System). The RDBMS sends the data back to the database server, which then passes the information back to the application server. The application server in turn passes that information to your ABAP/4 program. There is usually a separate computer dedicated to house the database server, and the RDBMS may run on that computer also, or may be installed on its own computer.
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