Communication Between tp and ABAP 

Transport steps that are implemented in ABAP include activating ABAP Dictionary objects, structure conversion, and generating reports and screens. Executing these steps is complicated. tp uses the tables TRBAT and TRJOB to communicate with the ABAP transport programs.

To execute these steps, the R/3 System must be running with at least two background work processes. Furthermore, the batch job RDDIMPDP must be scheduled with the repeat-start option. We recommend scheduling this job event on a regular basis. If the job is not running, then start the program RDDNEWPP once in every R/3 System. Do this in client 000 and in all clients that are used as the source or target for a transport, and do it as a user that has CTS administration authorization, such as DDIC.

Once tp has sent the corresponding event to the R/3 System, RDDIMPDP checks table TRBAT to see if there is anything to do. If there is, it starts the required programs (for example, mass activation) in the background, schedules itself again, and then stops.

RDDIMPDP automatically recognizes if a previous step was terminated and restarts the action. However, this can only be done with two background work processes.

RDDIMPDP recognizes terminated import steps by checking table TRJOB.