Answer:   1) Build your flow service like this:
Sequence{Main Block}[EXIT ON: SUCCESS]
Sequence{Try Block}[EXIT ON: FAILURE]
Sequence{catch Block}[EXIT ON: DONE]
2) 1)sequence(outer sequence-exit on success).
2)sequence(Try block with service logic(inner sequence & child
to outer sequence)-exit on failure).
3)sequence(Catch block with any errors found in try block
(inner sequence & child to outer sequence)-exit
on done).
4)Branch step with retrying the errors
3)we can insert the finally block by
Sequence(Exit on success) MAIN
Sequence( Exit of failure) TRY
Sequence( Exit on done) CATCH
Sequence(Exit on failure) FINALLY