COMMIT WORK in ABAP OO and BAPI

[szyba]

Hello, 

I have a code with comment. I need to use "COMMIT WORK" in ABAP Object Oriented but I know it don't work just like in Functional Module. I found DEMO_TRANSACTION_SERVICE, but is not enough. 

METHOD SAVE_ALL.
 DATA: transaction         TYPE REF TO if_os_transaction,
          transaction_manager TYPE REF TO if_os_transaction_manager.

    IF cl_os_system=>init_state IS INITIAL.
      cl_os_system=>init_and_set_modes( i_external_commit = oscon_false
                                        i_update_mode = oscon_dmode_update_task_sync ).
    ENDIF.

    transaction_manager = cl_os_system=>get_transaction_manager( ).
    transaction = transaction_manager->create_transaction( ).
TRY.
 transaction->start( ).
"(1)
MODIFI ztable_1 from ls_1.
    IF sy-subrc <> 0.
      RAISE EXCEPTION TYPE zcx_wm_util
        EXPORTING
          textid = zcx_wm_util=>data_not_saved.
    ENDIF.
"(2)
MODIFI ztable_2 from ls_2.
    IF sy-subrc <> 0.
      RAISE EXCEPTION TYPE zcx_wm_util
        EXPORTING
          textid = zcx_wm_util=>data_not_saved.
    ENDIF.
"(3)
    CALL FUNCTION 'BAPI_GOODSMVT_CREATE' " DESTINATION 'NONE'
      EXPORTING
        goodsmvt_header  = ls_goodsmvt_header
        goodsmvt_code    = iv_movement
      IMPORTING
        goodsmvt_headret = ls_goodsmvt_headret
      TABLES
        goodsmvt_item    = lt_goodsmvt_item
        return           = rt_error.

    DATA(lv_check_error) = REDUCE i( INIT x = 0 FOR <line> IN rt_error
                                     WHERE ( type = 'E' OR type = 'A' ) NEXT x = x + 1 ).

    IF lv_check_error = 0.
"HERE IS DUMP
" Do I need use TRANSACTION COMMIT?
      CALL FUNCTION 'BAPI_TRANSACTION_COMMIT'
        EXPORTING
          wait   = abap_true
        IMPORTING
          return = rt_error.
    ELSE.
      RAISE EXCEPTION TYPE zcx_wm_util
        EXPORTING
          textid = zcx_wm_util=>goodsmvt_not_create.
    ENDIF.


    WAIT UP TO 2 SECONDS.

    CALL FUNCTION 'L_TO_CREATE_MULTIPLE' 
...

    IF sy-subrc <> 0.
" Do I need use ROLLBACK?
      CALL FUNCTION 'BAPI_TRANSACTION_ROLLBACK'
        IMPORTING
          return = rt_error.

      RAISE EXCEPTION TYPE zcx_wm_util
        EXPORTING
          textid = zcx_wm_util=>data_not_saved.
    ENDIF.


        transaction->end( ). "Succes if all is ok


      CATCH zcx_wm_util INTO DATA(lx_wm_utill).
" Not so good, needed rollback all changes
         transaction->undo( ). "
        clear_screens_data( ).
ENDTRY.
ENDMETHOD.

 with comment