Transport Request Export/Release and Import Process in Background level:

Assume We do export(release) from source DEV to target QAS here,

• During release or export(done in source DEV) state cofile and data file creates in DEV, at the same time import buffer is created in QAS
• Now, tp calls R3trans and stores the object data extracted from the database in data files in the transport sub-directory 'data'.
• During import phase, tp passes the TR info of import buffer of QAS to transport sub-directory 'tmp' for use by R3trans.
• R3trans reads this tmp folder as well as reads corresponding 'data' file in Trans directory, connects directly to the database to perform inserts  or updates to the included objects.
• After R3trans finishes performing inserts or updates, it passes an exit code to tp.
• R3trans writes a log file in transport sub-directory 'tmp'. After R3trans completes its work, tp moves this log file to the transport sub-directory 'log'
• tp and RDDIMPDP communicate via table TRBAT
  
• tp triggers the import dispatcher RDDIMPDP by sending the event SAP_TRIGGER_RDDIMPDP with the help of the tool sapevt
• When RDDIMPDP is started, it checks the table TRBAT to find out if there is an action to be performed for the transport requests
• Each of the required background tasks receives a job number generated by background processing. This job number and the step ID are inserted into table TRJOB by the RDD* jobs.