ME_PROCESSPO_CUST-GET_HEADER get items? get accounting?

Question

I am using BADI IF_EX_ME_PROCESS_PO_CUST to perform custom processing for P.O.s. In one scenario the only method that gets broken into is "GET_HEADER". I have the code below activated so far. My lack of OO knowledge is handicapping me. Ihaven't seemd to be able to find a clear cut answer online yet. I need to do two things:
1) Be able to read the line item details fields using what I have so far, or another way.
2) I need to read the accounting details to read the GL Number as well.
I would like to isolate all of this code in the "GET_HEADER" if possible. The code would help.
   Thank-You.
METHOD if_ex_me_process_po_cust~process_header.
DATA: rzcl_im_4ppi_glpo4 TYPE REF TO zcl_im_4ppi_glpo4.
DATA : ls_mepoheader TYPE mepoheader.
DATA: ls_item       TYPE purchase_order_items.
DATA: zcl_po        TYPE REF TO cl_po_header_handle_mm.
DATA: ls_items      TYPE purchase_order_item.
data: lt_mepoitem   TYPE STANDARD TABLE OF mepoitem.
data: ls_mepoitem   TYPE mepoitem.
*create the class instance from P.O. class interface
CREATE OBJECT rzcl_im_4ppi_glpo4.
*get header and item data
ls_mepoheader = im_header->get_data( ).
ls_item       = im_header->get_items( ).
*created a second instance from cl_po_header_handle_mm
CREATE OBJECT zcl_po exporting im_po_number = ls_mepoheader-ebeln.

Answer 1

Resolved it Thanks to a great link, Thank-You Vinod Kumar T:
http://wiki.sdn.sap.com/wiki/display/ABAP/PurchaseOrderDataExtractionusingABAPClasses#PurchaseOrderDataExtractionusingABAPClasses-RelatedContent
METHOD if_ex_me_process_po_cust~process_header.
  DATA: rzcl_im_4ppi_glpo4 TYPE REF TO zcl_im_4ppi_glpo4.
  DATA : lt_items      TYPE purchase_order_items.
  DATA : ls_mepoheader TYPE mepoheader.
  DATA: ls_item       TYPE purchase_order_items.
  DATA: zcl_po        TYPE REF TO cl_po_header_handle_mm.
  DATA: ls_items      TYPE purchase_order_item.
  DATA: lt_mepoitem   TYPE STANDARD TABLE OF mepoitem.
  DATA: ls_mepoitem   TYPE mepoitem.
  DATA: lt_accounting TYPE purchase_order_accountings.
  DATA: ls_accounting TYPE purchase_order_accounting.
  DATA: lt_mepoacct   TYPE STANDARD TABLE OF mepoaccounting.
  DATA: ls_mepoacct   TYPE mepoaccounting.
*create the class instance from P.O. class interface
  CREATE OBJECT rzcl_im_4ppi_glpo4.
*get header and item data
  ls_mepoheader = im_header->get_data( ).
*  ls_item       = im_header->get_items( ).
*created a second instance from cl_po_header_handle_mm
  CREATE OBJECT zcl_po
    EXPORTING
      im_po_number = ls_mepoheader-ebeln.
* Extract PO Item Information **
  REFRESH : lt_items.
  lt_items = zcl_po->if_purchase_order_mm~get_items( ).
  LOOP AT lt_items INTO ls_items.
    ls_mepoitem = ls_items-item->get_data( ).
    APPEND ls_mepoitem TO lt_mepoitem.
  ENDLOOP.
** Extract PO Account Assignments
  REFRESH : lt_accounting.
  lt_accounting = ls_items-item->get_accountings( ).
  LOOP AT lt_accounting INTO ls_accounting.
    ls_mepoacct = ls_accounting-accounting->get_data( ).
    APPEND ls_mepoacct TO lt_mepoacct.
  ENDLOOP.
ENDMETHOD.