ABAP Memory Management: EXPORT, IMPORT, Shared Memory

" Program 1: Export data
DATA: ls_customer TYPE kna1,
      lt_orders   TYPE TABLE OF vbak.

" Prepare data
ls_customer-kunnr = '0000001000'.
ls_customer-name1 = 'Mustermann GmbH'.

" Export to ABAP Memory
EXPORT customer = ls_customer
       orders   = lt_orders
  TO MEMORY ID 'ZCUSTOMER_DATA'.


" Program 2: Import data (after CALL TRANSACTION)
DATA: ls_customer TYPE kna1,
      lt_orders   TYPE TABLE OF vbak.

IMPORT customer = ls_customer
       orders   = lt_orders
  FROM MEMORY ID 'ZCUSTOMER_DATA'.

IF sy-subrc = 0.
  WRITE: / 'Customer:', ls_customer-name1.
ENDIF.

" Release memory
FREE MEMORY ID 'ZCUSTOMER_DATA'.

" SAP Memory for field pre-population
" Parameter IDs are defined in Data Dictionary

" Set value
SET PARAMETER ID 'KUN' FIELD '0000001000'.
SET PARAMETER ID 'BUK' FIELD '1000'.

" Read value
DATA: lv_kunnr TYPE kunnr,
      lv_bukrs TYPE bukrs.

GET PARAMETER ID 'KUN' FIELD lv_kunnr.
GET PARAMETER ID 'BUK' FIELD lv_bukrs.

WRITE: / 'Customer:', lv_kunnr,
       / 'Company Code:', lv_bukrs.


" Call transaction with pre-populated values
SET PARAMETER ID 'KUN' FIELD '0000001000'.
CALL TRANSACTION 'XD03' AND SKIP FIRST SCREEN.

" Persistent storage across sessions
" Table: INDX or custom cluster table

DATA: ls_settings TYPE ty_settings.

ls_settings-user    = sy-uname.
ls_settings-variant = 'DEFAULT'.
ls_settings-values  = lt_values.

" Save to database
EXPORT settings = ls_settings
  TO DATABASE indx(zs)           " Table INDX, Area 'ZS'
  ID |SETTINGS_{ sy-uname }|.    " Unique key


" Read later
DATA: ls_settings TYPE ty_settings.

IMPORT settings = ls_settings
  FROM DATABASE indx(zs)
  ID |SETTINGS_{ sy-uname }|.

IF sy-subrc = 0.
  " Settings found
  WRITE: / 'Variant:', ls_settings-variant.
ENDIF.


" Delete
DELETE FROM DATABASE indx(zs)
  ID |SETTINGS_{ sy-uname }|.

" Create table in SE11:
" Name: ZCUSTOM_CLUSTER
" Fields:
"   - RELID (CHAR 2) - Area
"   - SRTFD (CHAR 40) - ID/Key
"   - Cluster fields (CLUSTR, CLUSTD)

" Usage
EXPORT data = ls_data
  TO DATABASE zcustom_cluster(AA)
  ID lv_key.

IMPORT data = ls_data
  FROM DATABASE zcustom_cluster(AA)
  ID lv_key.

" 1. Define area class (SE24)
CLASS zcl_shared_area DEFINITION
  PUBLIC FINAL
  CREATE PUBLIC
  SHARED MEMORY ENABLED.

  PUBLIC SECTION.
    INTERFACES: if_shm_build_instance.

    DATA: mt_customers TYPE HASHED TABLE OF kna1 WITH UNIQUE KEY kunnr.

    METHODS: load_customers.
ENDCLASS.

CLASS zcl_shared_area IMPLEMENTATION.
  METHOD if_shm_build_instance~build.
    " Called when area is built
    DATA(lo_area) = CAST zcl_shared_area( bound_memory ).
    lo_area->load_customers( ).
  ENDMETHOD.

  METHOD load_customers.
    SELECT * FROM kna1
      INTO TABLE mt_customers
      UP TO 10000 ROWS.
  ENDMETHOD.
ENDCLASS.


" 2. Create Shared Memory Area in SHMA
" Name: ZSM_CUSTOMER_CACHE
" Root Class: ZCL_SHARED_AREA


" 3. Usage
DATA: lo_area   TYPE REF TO zcl_shared_area,
      lo_handle TYPE REF TO zcl_sm_customer_cache.

TRY.
    " Read access
    lo_handle = zcl_sm_customer_cache=>attach_for_read( ).
    lo_area = CAST zcl_shared_area( lo_handle->root ).

    " Use data
    READ TABLE lo_area->mt_customers INTO DATA(ls_customer)
      WITH KEY kunnr = '0000001000'.

    lo_handle->detach( ).

  CATCH cx_shm_attach_error INTO DATA(lx_error).
    " Area doesn't exist yet -> build
    TRY.
        zcl_sm_customer_cache=>build(
          EXPORTING
            inst_name = zcl_sm_customer_cache=>default_instance
        ).
      CATCH cx_shm_build_error.
    ENDTRY.
ENDTRY.

" Main program
DATA: ls_order TYPE vbak.

ls_order-vbeln = '0000000001'.
ls_order-kunnr = '0000001000'.

" Provide data for called program
EXPORT order = ls_order TO MEMORY ID 'ZORDER_EDIT'.

" Call transaction
CALL TRANSACTION 'ZORDER_CHANGE'.

" After return: Read changed data
IMPORT order = ls_order FROM MEMORY ID 'ZORDER_EDIT'.
FREE MEMORY ID 'ZORDER_EDIT'.


" Called program (ZORDER_CHANGE)
DATA: ls_order TYPE vbak.

IMPORT order = ls_order FROM MEMORY ID 'ZORDER_EDIT'.

" Processing...

" Return changed data
EXPORT order = ls_order TO MEMORY ID 'ZORDER_EDIT'.

LEAVE PROGRAM.

CLASS zcl_memory_helper DEFINITION.
  PUBLIC SECTION.
    " ABAP Memory
    CLASS-METHODS: export_to_memory
      IMPORTING iv_id   TYPE clike
                iv_data TYPE any.

    CLASS-METHODS: import_from_memory
      IMPORTING iv_id           TYPE clike
      EXPORTING ev_data         TYPE any
      RETURNING VALUE(rv_found) TYPE abap_bool.

    CLASS-METHODS: free_memory
      IMPORTING iv_id TYPE clike.

    " SAP Memory
    CLASS-METHODS: set_parameter
      IMPORTING iv_id    TYPE clike
                iv_value TYPE clike.

    CLASS-METHODS: get_parameter
      IMPORTING iv_id          TYPE clike
      RETURNING VALUE(rv_value) TYPE string.

    " Database Cluster
    CLASS-METHODS: save_to_db
      IMPORTING iv_id   TYPE clike
                iv_data TYPE any.

    CLASS-METHODS: load_from_db
      IMPORTING iv_id           TYPE clike
      EXPORTING ev_data         TYPE any
      RETURNING VALUE(rv_found) TYPE abap_bool.

    CLASS-METHODS: delete_from_db
      IMPORTING iv_id TYPE clike.
ENDCLASS.

CLASS zcl_memory_helper IMPLEMENTATION.
  METHOD export_to_memory.
    EXPORT data = iv_data TO MEMORY ID iv_id.
  ENDMETHOD.

  METHOD import_from_memory.
    IMPORT data = ev_data FROM MEMORY ID iv_id.
    rv_found = xsdbool( sy-subrc = 0 ).
  ENDMETHOD.

  METHOD free_memory.
    FREE MEMORY ID iv_id.
  ENDMETHOD.

  METHOD set_parameter.
    SET PARAMETER ID iv_id FIELD iv_value.
  ENDMETHOD.

  METHOD get_parameter.
    GET PARAMETER ID iv_id FIELD rv_value.
  ENDMETHOD.

  METHOD save_to_db.
    DATA(lv_id) = CONV indx_srtfd( iv_id ).
    EXPORT data = iv_data TO DATABASE indx(zm) ID lv_id.
    COMMIT WORK.
  ENDMETHOD.

  METHOD load_from_db.
    DATA(lv_id) = CONV indx_srtfd( iv_id ).
    IMPORT data = ev_data FROM DATABASE indx(zm) ID lv_id.
    rv_found = xsdbool( sy-subrc = 0 ).
  ENDMETHOD.

  METHOD delete_from_db.
    DATA(lv_id) = CONV indx_srtfd( iv_id ).
    DELETE FROM DATABASE indx(zm) ID lv_id.
    COMMIT WORK.
  ENDMETHOD.
ENDCLASS.


" Usage
" ABAP Memory
zcl_memory_helper=>export_to_memory(
  iv_id   = 'MY_DATA'
  iv_data = ls_data
).

IF zcl_memory_helper=>import_from_memory(
     iv_id   = 'MY_DATA'
     IMPORTING ev_data = ls_data
   ) = abap_true.
  " Data found
ENDIF.

" Database
zcl_memory_helper=>save_to_db(
  iv_id   = |USER_{ sy-uname }_SETTINGS|
  iv_data = ls_settings
).

CLASS zcl_user_settings DEFINITION.
  PUBLIC SECTION.
    TYPES: BEGIN OF ty_settings,
             layout   TYPE string,
             pagesize TYPE i,
             filters  TYPE string,
           END OF ty_settings.

    METHODS: constructor
      IMPORTING iv_program TYPE sy-repid DEFAULT sy-repid.

    METHODS: load
      RETURNING VALUE(rs_settings) TYPE ty_settings.

    METHODS: save
      IMPORTING is_settings TYPE ty_settings.

    METHODS: delete.

  PRIVATE SECTION.
    DATA: mv_id TYPE indx_srtfd.
ENDCLASS.

CLASS zcl_user_settings IMPLEMENTATION.
  METHOD constructor.
    mv_id = |{ iv_program }_{ sy-uname }|.
  ENDMETHOD.

  METHOD load.
    IMPORT settings = rs_settings
      FROM DATABASE indx(us)
      ID mv_id.

    IF sy-subrc <> 0.
      " Defaults
      rs_settings-pagesize = 100.
    ENDIF.
  ENDMETHOD.

  METHOD save.
    EXPORT settings = is_settings
      TO DATABASE indx(us)
      ID mv_id.
    COMMIT WORK.
  ENDMETHOD.

  METHOD delete.
    DELETE FROM DATABASE indx(us) ID mv_id.
    COMMIT WORK.
  ENDMETHOD.
ENDCLASS.


" Usage
DATA(lo_settings) = NEW zcl_user_settings( ).
DATA(ls_settings) = lo_settings->load( ).

" Change settings
ls_settings-pagesize = 50.
lo_settings->save( ls_settings ).

" Shared Memory for frequently needed master data

" Area Root Class
CLASS zcl_material_cache DEFINITION
  PUBLIC FINAL
  CREATE PUBLIC
  SHARED MEMORY ENABLED.

  PUBLIC SECTION.
    INTERFACES: if_shm_build_instance.

    TYPES: ty_materials TYPE HASHED TABLE OF mara WITH UNIQUE KEY matnr.

    DATA: mt_materials TYPE ty_materials,
          mv_loaded_at TYPE timestampl.

    METHODS: get_material
      IMPORTING iv_matnr         TYPE matnr
      RETURNING VALUE(rs_material) TYPE mara.

    METHODS: is_expired
      RETURNING VALUE(rv_expired) TYPE abap_bool.
ENDCLASS.

CLASS zcl_material_cache IMPLEMENTATION.
  METHOD if_shm_build_instance~build.
    DATA(lo_root) = CAST zcl_material_cache( bound_memory ).

    SELECT * FROM mara
      INTO TABLE lo_root->mt_materials
      WHERE mtart IN ('FERT', 'HALB', 'ROH').

    GET TIME STAMP FIELD lo_root->mv_loaded_at.
  ENDMETHOD.

  METHOD get_material.
    READ TABLE mt_materials INTO rs_material
      WITH KEY matnr = iv_matnr.
  ENDMETHOD.

  METHOD is_expired.
    DATA: lv_now TYPE timestampl.
    GET TIME STAMP FIELD lv_now.

    " Invalidate cache after 1 hour
    rv_expired = xsdbool(
      lv_now - mv_loaded_at > 3600
    ).
  ENDMETHOD.
ENDCLASS.


" Usage
DATA: lo_handle TYPE REF TO zcl_sm_material,
      lo_cache  TYPE REF TO zcl_material_cache.

TRY.
    lo_handle = zcl_sm_material=>attach_for_read( ).
    lo_cache = lo_handle->root.

    " Check cache validity
    IF lo_cache->is_expired( ).
      lo_handle->detach( ).
      zcl_sm_material=>invalidate_instance( ).
      " Rebuilt on next access
    ELSE.
      DATA(ls_material) = lo_cache->get_material( lv_matnr ).
      lo_handle->detach( ).
    ENDIF.

  CATCH cx_shm_attach_error.
    " Fallback: Direct from DB
    SELECT SINGLE * FROM mara
      WHERE matnr = @lv_matnr
      INTO @ls_material.
ENDTRY.

" For large data volumes: Compression
DATA: lt_big_table TYPE TABLE OF vbak,
      lv_xstring   TYPE xstring.

" Data to compressed XString
EXPORT data = lt_big_table
  TO DATA BUFFER lv_xstring
  COMPRESSION ON.

" Save to DB
UPDATE zcache SET data = lv_xstring
  WHERE id = lv_id.


" Load again
SELECT SINGLE data FROM zcache
  WHERE id = @lv_id
  INTO @lv_xstring.

IMPORT data = lt_big_table
  FROM DATA BUFFER lv_xstring.

" TRY-CLEANUP for clean cleanup
DATA: lv_memory_id TYPE c LENGTH 30 VALUE 'ZTEMP_DATA'.

TRY.
    EXPORT data = ls_data TO MEMORY ID lv_memory_id.

    " Processing that may fail
    process_data( ).

    " Release normally
    FREE MEMORY ID lv_memory_id.

  CATCH cx_root INTO DATA(lx_error).
    " Release also on error
    FREE MEMORY ID lv_memory_id.
    RAISE EXCEPTION lx_error.
ENDTRY.


" Or with CLEANUP
TRY.
    EXPORT data = ls_data TO MEMORY ID lv_memory_id.
    process_data( ).

  CLEANUP.
    " Executed automatically on exception
    FREE MEMORY ID lv_memory_id.
ENDTRY.

" Main program: Pass data to report
DATA: lt_selections TYPE TABLE OF rsparams.

" Export data
EXPORT selections = lt_selections
  TO MEMORY ID 'ZREPORT_DATA'.

" Call report
SUBMIT zreport_process AND RETURN.

" Get result
DATA: lt_results TYPE ty_result_tab.
IMPORT results = lt_results
  FROM MEMORY ID 'ZREPORT_RESULTS'.

FREE MEMORY ID 'ZREPORT_DATA'.
FREE MEMORY ID 'ZREPORT_RESULTS'.


" Report (ZREPORT_PROCESS)
DATA: lt_selections TYPE TABLE OF rsparams,
      lt_results    TYPE ty_result_tab.

" Data from caller
IMPORT selections = lt_selections
  FROM MEMORY ID 'ZREPORT_DATA'.

" Processing...

" Return result
EXPORT results = lt_results
  TO MEMORY ID 'ZREPORT_RESULTS'.