Shared memory - free_instance method doesn't work

Question

I am using shared memory to store data, set the data in a program and then read in an update task.  My write and read both work, but I would like to "delete" the shared memory instance after the read in the update task.  I am using the free_instance method - it works sometimes, but a very small percentage of the time.  Here is the code I am using:
To write to shared memory:
data: lv_inst        type shm_inst_name,
          lo_shared_area type ref to z_cl_binkill_shared_area,
          lo_root        type ref to z_cl_binkill_rmnqty.
    lv_inst = ordim_confirm-matid.
    shift lv_inst LEFT DELETING LEADING space.
    concatenate ordim_confirm-who ordim_confirm-vlpla lv_inst into lv_inst.
    try.
    Attach Shared Area
      lo_shared_area = z_cl_binkill_shared_area=>attach_for_write( lv_inst ).
    Create Root Object ( Object to be created in Memory )
      create object lo_root area handle lo_shared_area.
    Set the value for our message
      lo_root->set_data( ordim_confirm ).
    Set the root back into the Area
      lo_shared_area->set_root(  lo_root ). "<- Note the 2 spaces before go_root (didn't work without!)
    Commit and detatch
      lo_shared_area->detach_commit( ).
    catch cx_shm_attach_error.
    endtry.
To read from shared memory and then (hopefully) delete:
DATA: lv_inst          TYPE shm_inst_name,
        ls_ordim_confirm TYPE /scwm/s_rf_ordim_confirm,
        lv_rc            TYPE shm_rc,
        lo_shared_area   TYPE REF TO z_cl_binkill_shared_area,
        lo_root          TYPE REF TO z_cl_binkill_rmnqty.
lv_inst = ls_ordim_c-matid.
          SHIFT lv_inst LEFT DELETING LEADING space.
          CONCATENATE ls_ordim_c-who ls_ordim_c-vlpla lv_inst INTO lv_inst.
          TRY.
              lo_shared_area = z_cl_binkill_shared_area=>attach_for_read( lv_inst ).
              lo_root        = lo_shared_area->root.
              TRY.
                  ls_ordim_confirm = lo_root->get_data( ).
                CATCH cx_root.
                  CLEAR ls_ordim_confirm.
              ENDTRY.
              lo_shared_area->detach( ).
              lv_rc = lo_shared_area->free_instance( lv_inst ).
            CATCH cx_shm_attach_error.
              CLEAR ls_ordim_confirm.
          ENDTRY.
Any ideas why the free_instance doesn't work?
Jeff Mathieson

Answer 1

If an UICommand element inside a UIData table does not invoke the method behind the action binding, then this generally means that the row object is out of the scope while the action event is getting to be fired. Test it by putting the managed bean in session scope and see if it will solve the problem. If so, and if you want to keep the managed bean in the request scope, then change/rearrange your data loading logic so that the data is available during at least the invocation phase of the JSF lifecycle. Or split the backing bean in two beans, one for strictly request-scoped data and another for strictly session-scoped data.