Howto replace an embedded FPM-Instance within a Web DynPro Application?

Question

Hi,
I have to build a Web DynPro application that displays an Navigation menu on the left side. On the right side within a UIViewContainer an embedded FPM Instance should be displayed depending on which entry I pressed on the Navigation menu. (Similiar to the Cockpit)
For Test purposes I have 2 buttons in the navigation menu. One to add the fpm and one to remove the fpm.
When I start the WD Application I first hit the addfpm button. And a new FPM Application is displayed within the UIViewElementContainer. When I hit the delfpm button the FPM will disappear. When I will the addfpm button again I get
a dump[1]
I have absolutely no idea why I get this dump.
Do I have to reset the FPM application remove removing it? Or is it possible to load a new FPM configuration in the FPM without removing it first?
Here are the Methods that I use to remove/add the FPM-Instance:
method ONACTIONADDFPM .
  DATA: L_VIEW_CONTROLLER_API TYPE REF TO IF_WD_VIEW_CONTROLLER.
  DATA: L_COMPONENT_USAGE TYPE REF TO IF_WD_COMPONENT_USAGE.
  DATA: lf_conf_key TYPE WDY_CONFIG_KEY.
  L_VIEW_CONTROLLER_API = wd_this->WD_GET_API( ).
  "Wenn die Komponente-Usage noch nicht vorhanden ist dann erstelle Sie:
  L_COMPONENT_USAGE = wd_this->WD_CPUSE_FPM( ).
  IF L_COMPONENT_USAGE->HAS_ACTIVE_COMPONENT( ) IS INITIAL.
    lf_conf_key-CONFIG_ID = '/PLMU/WDC_MAT_OIF_CFG'.
    L_COMPONENT_USAGE->CREATE_COMPONENT( EXPORTING COMPONENT_NAME = 'FPM_OIF_COMPONENT'
                                                   CONFIGURATION_ID = lf_conf_key ).
    "Komponente mit der View verknüpfen:
    L_VIEW_CONTROLLER_API->PREPARE_DYNAMIC_NAVIGATION(
      SOURCE_WINDOW_NAME = 'WINDOW'
      SOURCE_VUSAGE_NAME = 'MAIN_USAGE_0' "MAIN_USAGE1/UIVIEW_VCA_1'
      SOURCE_PLUG_NAME   = 'TO_FPM'
      TARGET_COMPONENT_NAME = 'FPM_OIF_COMPONENT'
      TARGET_COMPONENT_USAGE = 'FPM'
      TARGET_VIEW_NAME = 'FPM_WINDOW'
      TARGET_PLUG_NAME = 'DEFAULT'
      TARGET_EMBEDDING_POSITION = 'MAIN/FPMVIEW' "'MAIN_USAGE_0/UIVIEW_VCA_1'
    WD_THIS->FIRE_TO_FPM_PLG( ).
  ENDIF.
endmethod.
And then remove the FPM using this button action:
method ONACTIONDELFPM .
  DATA: L_VIEW_CONTROLLER_API TYPE REF TO IF_WD_VIEW_CONTROLLER.
  DATA: L_COMPONENT_USAGE TYPE REF TO IF_WD_COMPONENT_USAGE.
  L_VIEW_CONTROLLER_API = wd_this->WD_GET_API( ).
  "Wenn die Komponente-Usage vorhanden ist dann lösche sie:
  L_COMPONENT_USAGE = wd_this->WD_CPUSE_FPM( ).
  DATA: lo_event TYPE REF TO cl_fpm_event.
  lo_event = cl_fpm_event=>create_by_id( iv_event_id   = cl_fpm_event=>GC_EVENT_CLOSE  ).
  DATA: iwci_fpm TYPE REF TO IWCI_FPM_OIF_COMPONENT.
  iwci_fpm = wd_this->WD_CPIFC_FPM( ).
  CALL METHOD IWCI_FPM->CLOSE_DIALOG
    EXPORTING
      IO_EVENT        =  lo_event
      IV_EVENT_FAILED =  ABAP_FALSE
  IF L_COMPONENT_USAGE->HAS_ACTIVE_COMPONENT( ) IS NOT INITIAL.
    L_COMPONENT_USAGE->DELETE_COMPONENT( ).
    "FPM Ref holen und Exit-Event schicken:
    DATA: lo_fpm TYPE REF TO IF_FPM.
    lo_fpm = cl_fpm_factory=>get_instance( ).
   CHECK NOT lo_fpm IS INITIAL.
   DATA: lf_event        TYPE FPM_EVENT_ID.
   lf_event = cl_fpm_event=>GC_EVENT_CLOSE.
   lo_fpm->RAISE_EVENT_BY_ID( lf_event ).
  ENDIF.
endmethod.
The dump  says:
Access via 'NULL' object reference not possible.
The ABAP call hierarchy was:
Method: /PLMU/IWCI_WDI_FRW_OIF~OVERRIDE_EVENT of program /1BCWDY/0O2TST5VUWTCOBML1BE7==CP
Method: /PLMU/IF_FRW_CALLBACK_PROXY~OVERRIDE_EVENT of program /PLMU/CL_FRW_F_CALLBACK_PROXY=CP
Method: OVERRIDE_EVENT of program /PLMU/CL_FRW_CALLBACK_PROXY===CP
Method: OVERRIDE_EVENT_OIF of program /PLMU/CL_FRW_APPL_CNTRL_ASSISTCP
Method: OVERRIDE_EVENT_OIF of program /1BCWDY/0O2TST5VUWTCNOS8226Y==CP
Method: IWCI_IF_FPM_OIF_CONF_EXIT~OVERRIDE_EVENT_OIF of program /1BCWDY/0O2TST5VUWTCNOS8226Y==CP
Method: GET_UIBBS_FOR_EVENT of program /1BCWDY/0O2TST5VUWTCNAR83UZE==CP
Method: IWCI_IF_FPM_FLOORPLAN_COMP~GET_UIBBS_FOR_EVENT of program /1BCWDY/0O2TST5VUWTCNAR83UZE==CP
Method: IF_FPM_FLOORPLAN~GET_UIBBS_FOR_EVENT of program CL_FPM_OIF_INTERNAL===========CP
Method: GET_NEXT_UIBBS of program CL_FPM========================CP
Thanks
Sebastian

Answer 1

Chris yes you are right, there is some special logic in the nav app,
that I can't do with NWBC.
If I would use a Portal to display the FPM within an Iframe.
What happends when I replace the FPM in the Iframe with a new
FPM/URl. Will the old FPM in the Iframe just disappear or will
the FPM shutdown and release all the acquired locks?
I already did a simliar thing where I just used URLs
to display an FPM application within an IView/IFrame.
But when I replace the URL of the IView/IFrame with a new URL/FPM,
the old FPM only just disappered but no locks where released.
So displaying the same FPM again, gives me a message that the Object is already
locked.
Thanks
Sebastian