How does the interaction between the Dynpro and the ABAP/4 Modules takes place?
-A transaction is a collection os screens and ABAP/4 routines , controlled and implemented by a Dialog processor. The Dilaog processor processes screen after the screen , thereby triggering the appropriate
ABAP/4 processing of every screen .For each screen, the system implements the flow logic that contains the corresponding ABAP/4 processing. The controls pass from screen flow logic to ABAP/4 code and back.