In the Dialog programming(Module Pool programming) basically two main events,,
PBO and PAI.
PBO(Process before Output ) is the default event which will get triggerred whenever there is a call to the screen you have designed.
it means it will processs or execute the entire code in that module before displaying the screen. usually the default values in the gui elements in that screen and their validations will be given in the PBO..
Say for an example you have designed a screen Ytest_screen with the number 100.
Screen will have these three elements :
1. Flow Logic,
2. Screen Layout
3. Field attributes.
In the screen layout you will design your screen and place all the gui elements(check boxes, buttons, input output fields table controls, tab strips etc etc).
For all these fields you will give some attributes (input only, Input/output enables, function codes for the push buttons, etc etc).
You will write the logic in the Flow logic.
In the flow logic you will by default have two events,, PBO and PAI.
when you uncomment any these modules, and double click on them,, it will take you the abap program assiciated to it.
and you will find module and endmodule.. you will have to write the entire logic for PBO and PAI in that module and endmodule.
when you run the transaction or the abap program, when you make a call to the screen..
initially PBO will get triggerred.
and in the screen when you perform any action, like pressing button etc.. PAI will get triggered and those events can be caught using the system variable called SY-UCOMM.
and after every PAI, by default PBO will again get triggered.
if you still have queries, don't hesitate to ask..
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Thanks-
Rahul
Bluesky
