Generic Extraction with delta

Question

Hi Every one,
I use an extractor based on a function module which is copy of the RSAX_BIW_GET_DATA_SIMPLE and gets delta records.
I have  a doubt of how the communication happens between BW and R/3 when delta info package is ran inorder to get delta records.
Can any one explain how this FM RSAX_BIW_GET_DATA_SIMPLE works ie., the input parameters,usage of static var, Cursors etc?
FUNCTION RSAX_BIW_GET_DATA_SIMPLE.
""Lokale Schnittstelle:
*"  IMPORTING
*"     VALUE(I_REQUNR) TYPE  SRSC_S_IF_SIMPLE-REQUNR
*"     VALUE(I_DSOURCE) TYPE  SRSC_S_IF_SIMPLE-DSOURCE OPTIONAL
*"     VALUE(I_MAXSIZE) TYPE  SRSC_S_IF_SIMPLE-MAXSIZE OPTIONAL
*"     VALUE(I_INITFLAG) TYPE  SRSC_S_IF_SIMPLE-INITFLAG OPTIONAL
*"     VALUE(I_READ_ONLY) TYPE  SRSC_S_IF_SIMPLE-READONLY OPTIONAL
*"     VALUE(I_REMOTE_CALL) TYPE  SBIWA_FLAG DEFAULT SBIWA_C_FLAG_OFF
*"  TABLES
*"      I_T_SELECT TYPE  SRSC_S_IF_SIMPLE-T_SELECT OPTIONAL
*"      I_T_FIELDS TYPE  SRSC_S_IF_SIMPLE-T_FIELDS OPTIONAL
*"      E_T_DATA STRUCTURE  SFLIGHT OPTIONAL
*"  EXCEPTIONS
*"      NO_MORE_DATA
*"      ERROR_PASSED_TO_MESS_HANDLER
Example: DataSource for table SFLIGHT
  TABLES: SFLIGHT.
Auxiliary Selection criteria structure
  DATA: L_S_SELECT TYPE SRSC_S_SELECT.
Maximum number of lines for DB table
  STATICS: S_S_IF TYPE SRSC_S_IF_SIMPLE,
counter
          S_COUNTER_DATAPAKID LIKE SY-TABIX,
cursor
          S_CURSOR TYPE CURSOR.
Select ranges
  RANGES: L_R_CARRID  FOR SFLIGHT-CARRID,
          L_R_CONNID  FOR SFLIGHT-CONNID.
Initialization mode (first call by SAPI) or data transfer mode
(following calls) ?
  IF I_INITFLAG = SBIWA_C_FLAG_ON.
Initialization: check input parameters
                buffer input parameters
                prepare data selection
Check DataSource validity
    CASE I_DSOURCE.
      WHEN '0SAPI_SFLIGHT_SIMPLE'.
      WHEN OTHERS.
        IF 1 = 2. MESSAGE E009(R3). ENDIF.
this is a typical log call. Please write every error message like this
        LOG_WRITE 'E'                  "message type
                  'R3'                 "message class
                  '009'                "message number
                  I_DSOURCE   "message variable 1
                  ' '.                 "message variable 2
        RAISE ERROR_PASSED_TO_MESS_HANDLER.
    ENDCASE.
    APPEND LINES OF I_T_SELECT TO S_S_IF-T_SELECT.
Fill parameter buffer for data extraction calls
    S_S_IF-REQUNR    = I_REQUNR.
    S_S_IF-DSOURCE = I_DSOURCE.
    S_S_IF-MAXSIZE   = I_MAXSIZE.
Fill field list table for an optimized select statement
(in case that there is no 1:1 relation between InfoSource fields
and database table fields this may be far from beeing trivial)
    APPEND LINES OF I_T_FIELDS TO S_S_IF-T_FIELDS.
  ELSE.                 "Initialization mode or data extraction ?
Data transfer: First Call      OPEN CURSOR + FETCH
               Following Calls FETCH only
First data package -> OPEN CURSOR
    IF S_COUNTER_DATAPAKID = 0.
Fill range tables BW will only pass down simple selection criteria
of the type SIGN = 'I' and OPTION = 'EQ' or OPTION = 'BT'.
      LOOP AT S_S_IF-T_SELECT INTO L_S_SELECT WHERE FIELDNM = 'CARRID'.
        MOVE-CORRESPONDING L_S_SELECT TO L_R_CARRID.
        APPEND L_R_CARRID.
      ENDLOOP.
      LOOP AT S_S_IF-T_SELECT INTO L_S_SELECT WHERE FIELDNM = 'CONNID'.
        MOVE-CORRESPONDING L_S_SELECT TO L_R_CONNID.
        APPEND L_R_CONNID.
      ENDLOOP.
Determine number of database records to be read per FETCH statement
from input parameter I_MAXSIZE. If there is a one to one relation
between DataSource table lines and database entries, this is trivial.
In other cases, it may be impossible and some estimated value has to
be determined.
      OPEN CURSOR WITH HOLD S_CURSOR FOR
      SELECT (S_S_IF-T_FIELDS) FROM SFLIGHT
                               WHERE CARRID  IN L_R_CARRID AND
                                     CONNID  IN L_R_CONNID.
    ENDIF.                             "First data package ?
Fetch records into interface table.
  named E_T_'Name of extract structure'.
    FETCH NEXT CURSOR S_CURSOR
               APPENDING CORRESPONDING FIELDS
               OF TABLE E_T_DATA
               PACKAGE SIZE S_S_IF-MAXSIZE.
    IF SY-SUBRC <> 0.
      CLOSE CURSOR S_CURSOR.
      RAISE NO_MORE_DATA.
    ENDIF.
    S_COUNTER_DATAPAKID = S_COUNTER_DATAPAKID + 1.
  ENDIF.              "Initialization mode or data extraction ?
ENDFUNCTION.
Also how the delta queue  is loaded in rsa7 when the delta records made?
When the delta info package is ran, the delta queue in rsa7 is changed to '0'.How is that communication made in between them?
Please clear my doubts?
Regards,
Pra

Answer 1

Hi Suneel,
You can load delta to write optimized DSO. Your Data source will have delta load (through infopackage) and then with DTP (with Extraction Mehtod --> Delta) you can load delta records to this write optimized DSO. So only the new requests, which are not loaded yet will be loaded to WO-DSO. I tried it in system and it works.
They can be used in the following scenarios:
●      You use a write-optimized DataStore object as a temporary storage area for large sets of data if you are executing complex transformations for this data before it is written to the DataStore object. The data can then be updated to further (smaller) InfoProviders. You only have to create the complex transformations once for all data.
●      You use write-optimized DataStore objects as the EDW layer for saving data. Business rules are only applied when the data is updated to additional InfoProviders.
it is used when you don't want to wait for DSO activation and error troubleshooting. It will make raportable data available instantly.
Hope it helps...
Regards,
Ashish
Edited by: Ashish Tewari on May 6, 2009 1:33 PM