Controlling the Flow of ABAP Programs by Events

Controlling the Flow of ABAP Programs by Events

The program flow of an executable program (report) is controlled by an invisible system program dependent on external events. You can assign processing blocks to events in the executable program using event keywords.

A significant feature of executable ABAP programs (type 1 programs) is that they are made up of processing blocks for events. There are various event classes:

When reading data from the database, the system program creates a series of events. The sequence of these events follows a fixed scheme and is partly defined by the used logical database.

During the creation of output lists, events occur that can be used for list formatting.

During the display of lists on the screen, the user can produce interactive list events for interactive reporting.

The interface between events and the program is provided by event keywords. The system always starts a processing block when the corresponding event occurs (see Program Construction and Execution).

The flow control inside a processing block (internal control) is described in Controlling the Flow of an ABAP Program. This section describes the external control of an ABAP program and the possible events involved:

Defining Processing Blocks

Events and their Event Keywords

Terminating Processing Blocks