ABAP Application Logging: BAL, CL_BAL_LOG, SLG1

Basic Concept

Element	Description
Log Object	Grouping (e.g., application) - maintain in SLG0
Sub-Object	Subcategory of the Log Object
Log Handle	Unique ID of a log instance
Message	Individual log message
SLG1	Transaction for log display

Message Types

Type	Meaning	Icon
A	Abort	Red
E	Error	Red
W	Warning	Yellow
I	Information	Blue
S	Success	Green

Examples

1. Create a Simple Log

DATA: lv_log_handle TYPE balloghndl,
      ls_log        TYPE bal_s_log.

" Log header
ls_log-object    = 'ZTEST'.       " Log object (from SLG0)
ls_log-subobject = 'PROCESS'.     " Sub-object
ls_log-aldate    = sy-datum.
ls_log-altime    = sy-uzeit.
ls_log-aluser    = sy-uname.
ls_log-alprog    = sy-repid.
ls_log-extnumber = 'My Processing 001'.

" Create log
CALL FUNCTION 'BAL_LOG_CREATE'
  EXPORTING
    i_s_log                 = ls_log
  IMPORTING
    e_log_handle            = lv_log_handle
  EXCEPTIONS
    log_header_inconsistent = 1
    OTHERS                  = 2.

IF sy-subrc <> 0.
  RETURN.
ENDIF.

" Add message
DATA: ls_msg TYPE bal_s_msg.

ls_msg-msgty = 'S'.
ls_msg-msgid = 'ZMYAPP'.
ls_msg-msgno = '001'.
ls_msg-msgv1 = 'Processing started'.

CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle     = lv_log_handle
    i_s_msg          = ls_msg
  EXCEPTIONS
    log_not_found    = 1
    msg_inconsistent = 2
    OTHERS           = 3.

" Additional messages
ls_msg-msgty = 'I'.
ls_msg-msgv1 = '100 records processed'.
CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING i_log_handle = lv_log_handle i_s_msg = ls_msg.

ls_msg-msgty = 'S'.
ls_msg-msgv1 = 'Processing completed'.
CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING i_log_handle = lv_log_handle i_s_msg = ls_msg.

" Save log
CALL FUNCTION 'BAL_DB_SAVE'
  EXCEPTIONS
    log_not_found       = 1
    save_not_allowed    = 2
    numbering_error     = 3
    OTHERS              = 4.

IF sy-subrc = 0.
  COMMIT WORK.
  WRITE: / 'Log saved'.
ENDIF.

2. OO Approach with CL_BAL_LOG

CLASS zcl_application_log DEFINITION.
  PUBLIC SECTION.
    METHODS: constructor
      IMPORTING iv_object    TYPE balobj_d
                iv_subobject TYPE balsubobj
                iv_extnumber TYPE balnrext OPTIONAL.

    METHODS: add_success
      IMPORTING iv_message TYPE string.

    METHODS: add_error
      IMPORTING iv_message TYPE string.

    METHODS: add_warning
      IMPORTING iv_message TYPE string.

    METHODS: add_info
      IMPORTING iv_message TYPE string.

    METHODS: add_exception
      IMPORTING ix_error TYPE REF TO cx_root.

    METHODS: save
      RETURNING VALUE(rv_success) TYPE abap_bool.

    METHODS: display.

    METHODS: get_messages
      RETURNING VALUE(rt_messages) TYPE bapiret2_t.

  PRIVATE SECTION.
    DATA: mv_log_handle TYPE balloghndl.

    METHODS: add_message
      IMPORTING iv_type    TYPE sy-msgty
                iv_message TYPE string.
ENDCLASS.

CLASS zcl_application_log IMPLEMENTATION.
  METHOD constructor.
    DATA: ls_log TYPE bal_s_log.

    ls_log-object    = iv_object.
    ls_log-subobject = iv_subobject.
    ls_log-aldate    = sy-datum.
    ls_log-altime    = sy-uzeit.
    ls_log-aluser    = sy-uname.
    ls_log-alprog    = sy-repid.
    ls_log-extnumber = iv_extnumber.

    CALL FUNCTION 'BAL_LOG_CREATE'
      EXPORTING
        i_s_log      = ls_log
      IMPORTING
        e_log_handle = mv_log_handle
      EXCEPTIONS
        OTHERS       = 1.
  ENDMETHOD.

  METHOD add_message.
    DATA: ls_msg TYPE bal_s_msg.

    " Free message
    ls_msg-msgty = iv_type.
    ls_msg-msgid = 'ZLOG'.
    ls_msg-msgno = '000'.
    ls_msg-msgv1 = iv_message(50).
    IF strlen( iv_message ) > 50.
      ls_msg-msgv2 = iv_message+50(50).
    ENDIF.
    IF strlen( iv_message ) > 100.
      ls_msg-msgv3 = iv_message+100(50).
    ENDIF.
    IF strlen( iv_message ) > 150.
      ls_msg-msgv4 = iv_message+150(50).
    ENDIF.

    CALL FUNCTION 'BAL_LOG_MSG_ADD'
      EXPORTING
        i_log_handle = mv_log_handle
        i_s_msg      = ls_msg
      EXCEPTIONS
        OTHERS       = 1.
  ENDMETHOD.

  METHOD add_success.
    add_message( iv_type = 'S' iv_message = iv_message ).
  ENDMETHOD.

  METHOD add_error.
    add_message( iv_type = 'E' iv_message = iv_message ).
  ENDMETHOD.

  METHOD add_warning.
    add_message( iv_type = 'W' iv_message = iv_message ).
  ENDMETHOD.

  METHOD add_info.
    add_message( iv_type = 'I' iv_message = iv_message ).
  ENDMETHOD.

  METHOD add_exception.
    DATA: ls_msg TYPE bal_s_msg.

    ls_msg-msgty = 'E'.
    ls_msg-msgid = 'ZLOG'.
    ls_msg-msgno = '001'.
    ls_msg-msgv1 = ix_error->get_text( )(50).

    CALL FUNCTION 'BAL_LOG_MSG_ADD'
      EXPORTING
        i_log_handle = mv_log_handle
        i_s_msg      = ls_msg
      EXCEPTIONS
        OTHERS       = 1.
  ENDMETHOD.

  METHOD save.
    DATA: lt_log_handles TYPE bal_t_logh.

    APPEND mv_log_handle TO lt_log_handles.

    CALL FUNCTION 'BAL_DB_SAVE'
      EXPORTING
        i_t_log_handle   = lt_log_handles
      EXCEPTIONS
        log_not_found    = 1
        save_not_allowed = 2
        numbering_error  = 3
        OTHERS           = 4.

    rv_success = xsdbool( sy-subrc = 0 ).

    IF rv_success = abap_true.
      COMMIT WORK.
    ENDIF.
  ENDMETHOD.

  METHOD display.
    DATA: lt_log_handles TYPE bal_t_logh,
          ls_profile     TYPE bal_s_prof.

    APPEND mv_log_handle TO lt_log_handles.

    CALL FUNCTION 'BAL_DSP_PROFILE_STANDARD_GET'
      IMPORTING
        e_s_display_profile = ls_profile.

    CALL FUNCTION 'BAL_DSP_LOG_DISPLAY'
      EXPORTING
        i_t_log_handle      = lt_log_handles
        i_s_display_profile = ls_profile
      EXCEPTIONS
        OTHERS              = 1.
  ENDMETHOD.

  METHOD get_messages.
    DATA: lt_msg TYPE bal_t_msg,
          ls_msg TYPE bal_s_msg.

    CALL FUNCTION 'BAL_LOG_MSG_READ'
      EXPORTING
        i_log_handle = mv_log_handle
      IMPORTING
        e_t_msg      = lt_msg
      EXCEPTIONS
        OTHERS       = 1.

    LOOP AT lt_msg INTO ls_msg.
      APPEND VALUE bapiret2(
        type       = ls_msg-msgty
        id         = ls_msg-msgid
        number     = ls_msg-msgno
        message_v1 = ls_msg-msgv1
        message_v2 = ls_msg-msgv2
        message_v3 = ls_msg-msgv3
        message_v4 = ls_msg-msgv4
      ) TO rt_messages.
    ENDLOOP.
  ENDMETHOD.
ENDCLASS.


" Usage
DATA(lo_log) = NEW zcl_application_log(
  iv_object    = 'ZTEST'
  iv_subobject = 'BATCH'
  iv_extnumber = |Processing { sy-datum }|
).

lo_log->add_success( 'Processing started' ).
lo_log->add_info( '500 records loaded' ).

TRY.
    " Processing...
    lo_log->add_success( 'Processing successful' ).
  CATCH cx_root INTO DATA(lx_error).
    lo_log->add_exception( lx_error ).
ENDTRY.

IF lo_log->save( ).
  lo_log->display( ).
ENDIF.

3. Create Log Object in SLG0

Transaction: SLG0

1. Click "New Entries"
2. Object: ZTEST
3. Object text: My Test Application
4. Save

5. Create Sub-Object:
   - Sub-Object: BATCH
   - Text: Batch Processing

   - Sub-Object: ONLINE
   - Text: Online Processing

4. Log with Context (Additional Data)

DATA: lv_log_handle TYPE balloghndl,
      ls_log        TYPE bal_s_log,
      ls_msg        TYPE bal_s_msg.

" Create log
ls_log-object    = 'ZORDERS'.
ls_log-subobject = 'PROCESS'.
ls_log-extnumber = 'Order Processing'.

CALL FUNCTION 'BAL_LOG_CREATE'
  EXPORTING i_s_log = ls_log
  IMPORTING e_log_handle = lv_log_handle.

" Message with context
ls_msg-msgty = 'E'.
ls_msg-msgid = 'ZORD'.
ls_msg-msgno = '001'.
ls_msg-msgv1 = '0000001234'.  " Order number

" Context structure (for navigation)
DATA: ls_context TYPE bal_s_cont.
ls_context-tabname = 'VBAK'.
ls_context-value   = '0000001234'.

ls_msg-context-tabname = 'VBAK'.
ls_msg-context-value   = ls_context-value.

CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle = lv_log_handle
    i_s_msg      = ls_msg.

5. Read Logs from Database

DATA: lt_log_filter  TYPE bal_s_lfil,
      lt_log_header  TYPE balhdr_t,
      lt_log_handles TYPE bal_t_logh.

" Define filter
lt_log_filter-object    = VALUE #( ( sign = 'I' option = 'EQ' low = 'ZTEST' ) ).
lt_log_filter-subobject = VALUE #( ( sign = 'I' option = 'EQ' low = 'BATCH' ) ).
lt_log_filter-aldate    = VALUE #( ( sign = 'I' option = 'GE' low = sy-datum - 7 ) ).

" Search logs
CALL FUNCTION 'BAL_DB_SEARCH'
  EXPORTING
    i_s_log_filter     = lt_log_filter
  IMPORTING
    e_t_log_header     = lt_log_header
  EXCEPTIONS
    log_not_found      = 1
    no_filter_criteria = 2
    OTHERS             = 3.

IF sy-subrc = 0.
  WRITE: / 'Logs found:', lines( lt_log_header ).

  " Load logs
  CALL FUNCTION 'BAL_DB_LOAD'
    EXPORTING
      i_t_log_header = lt_log_header
    IMPORTING
      e_t_log_handle = lt_log_handles
    EXCEPTIONS
      OTHERS         = 1.

  " Display
  CALL FUNCTION 'BAL_DSP_LOG_DISPLAY'
    EXPORTING
      i_t_log_handle = lt_log_handles
    EXCEPTIONS
      OTHERS         = 1.
ENDIF.

6. Delete Log

DATA: lt_log_filter TYPE bal_s_lfil,
      lt_log_header TYPE balhdr_t.

" Find old logs (older than 30 days)
lt_log_filter-object = VALUE #( ( sign = 'I' option = 'EQ' low = 'ZTEST' ) ).
lt_log_filter-aldate = VALUE #( ( sign = 'I' option = 'LE' low = sy-datum - 30 ) ).

CALL FUNCTION 'BAL_DB_SEARCH'
  EXPORTING
    i_s_log_filter = lt_log_filter
  IMPORTING
    e_t_log_header = lt_log_header
  EXCEPTIONS
    OTHERS         = 1.

" Delete logs
IF lt_log_header IS NOT INITIAL.
  CALL FUNCTION 'BAL_DB_DELETE'
    EXPORTING
      i_t_logs_to_delete = lt_log_header
    EXCEPTIONS
      OTHERS             = 1.

  IF sy-subrc = 0.
    COMMIT WORK.
    WRITE: / 'Deleted:', lines( lt_log_header ), 'logs'.
  ENDIF.
ENDIF.

7. Callback for Detail Display

DATA: ls_msg     TYPE bal_s_msg,
      ls_clbk    TYPE bal_s_clbk.

" Define callback
ls_clbk-userexitf = 'Z_SHOW_ORDER_DETAILS'.  " Function module
ls_clbk-userexitp = sy-repid.                 " Program
ls_clbk-userexitt = ' '.

ls_msg-msgty   = 'E'.
ls_msg-msgid   = 'ZORD'.
ls_msg-msgno   = '001'.
ls_msg-msgv1   = lv_vbeln.
ls_msg-params-callback = ls_clbk.

CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle = lv_log_handle
    i_s_msg      = ls_msg.


" Function module for callback
FUNCTION z_show_order_details.
*"  IMPORTING
*"     VALUE(I_S_MSG) TYPE BAL_S_MSG
*"----------------------------------------------------------------------
  " Display order
  SET PARAMETER ID 'AUN' FIELD i_s_msg-msgv1.
  CALL TRANSACTION 'VA03' AND SKIP FIRST SCREEN.
ENDFUNCTION.

8. Hierarchical Log

DATA: lv_log_handle   TYPE balloghndl,
      lv_msg_handle   TYPE balmsghndl,
      ls_msg          TYPE bal_s_msg.

" Create main log
CALL FUNCTION 'BAL_LOG_CREATE'
  EXPORTING i_s_log = ls_log
  IMPORTING e_log_handle = lv_log_handle.

" Parent message
ls_msg-msgty = 'I'.
ls_msg-msgid = 'ZLOG'.
ls_msg-msgno = '000'.
ls_msg-msgv1 = 'Processing Customer 1000'.

CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle  = lv_log_handle
    i_s_msg       = ls_msg
  IMPORTING
    e_msg_handle  = lv_msg_handle.   " Handle for parent

" Child messages
ls_msg-msgv1 = '  Address updated'.
CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle     = lv_log_handle
    i_s_msg          = ls_msg
    i_msg_handle_par = lv_msg_handle.  " Parent handle

ls_msg-msgv1 = '  Contacts synchronized'.
CALL FUNCTION 'BAL_LOG_MSG_ADD'
  EXPORTING
    i_log_handle     = lv_log_handle
    i_s_msg          = ls_msg
    i_msg_handle_par = lv_msg_handle.

9. Log with Priority and Detail Level

DATA: ls_msg TYPE bal_s_msg.

" Detail level
ls_msg-detlevel = '1'.  " 1-9, higher = more detail
ls_msg-probclass = '1'. " Problem class 1 = important, 4 = unimportant

" Filter on display
DATA: ls_profile TYPE bal_s_prof.

CALL FUNCTION 'BAL_DSP_PROFILE_STANDARD_GET'
  IMPORTING e_s_display_profile = ls_profile.

" Only important messages (problem class 1-2)
ls_profile-mess_filter-probclass = VALUE #(
  ( sign = 'I' option = 'BT' low = '1' high = '2' )
).

CALL FUNCTION 'BAL_DSP_LOG_DISPLAY'
  EXPORTING
    i_t_log_handle      = lt_log_handles
    i_s_display_profile = ls_profile.

10. Automatic Log on Exceptions

CLASS zcl_logged_processor DEFINITION.
  PUBLIC SECTION.
    METHODS: constructor
      IMPORTING io_log TYPE REF TO zcl_application_log.

    METHODS: process
      IMPORTING it_data TYPE ty_data_tab
      RAISING   zcx_processing_error.

  PRIVATE SECTION.
    DATA: mo_log TYPE REF TO zcl_application_log.
ENDCLASS.

CLASS zcl_logged_processor IMPLEMENTATION.
  METHOD constructor.
    mo_log = io_log.
  ENDMETHOD.

  METHOD process.
    mo_log->add_info( |Processing { lines( it_data ) } entries| ).

    LOOP AT it_data INTO DATA(ls_data).
      TRY.
          " Processing
          process_single( ls_data ).
          mo_log->add_success( |Entry { ls_data-id } processed| ).

        CATCH cx_root INTO DATA(lx_error).
          mo_log->add_error( |Entry { ls_data-id }: { lx_error->get_text( ) }| ).

          " Abort on critical error
          IF lx_error IS INSTANCE OF zcx_critical_error.
            mo_log->add_error( 'Critical error - aborting' ).
            mo_log->save( ).
            RAISE EXCEPTION TYPE zcx_processing_error
              EXPORTING previous = lx_error.
          ENDIF.
      ENDTRY.
    ENDLOOP.

    mo_log->add_success( 'Processing completed' ).
  ENDMETHOD.
ENDCLASS.

11. Mass Logging (Performance)

DATA: lt_messages TYPE bal_t_msg,
      ls_msg      TYPE bal_s_msg.

" Collect messages instead of adding individually
LOOP AT lt_data INTO DATA(ls_data).
  ls_msg-msgty = 'S'.
  ls_msg-msgid = 'ZLOG'.
  ls_msg-msgno = '000'.
  ls_msg-msgv1 = |Record { ls_data-id } processed|.
  APPEND ls_msg TO lt_messages.
ENDLOOP.

" Add all at once
CALL FUNCTION 'BAL_LOG_MSGS_ADD'
  EXPORTING
    i_log_handle = lv_log_handle
    i_t_msg      = lt_messages
  EXCEPTIONS
    OTHERS       = 1.

" Save once
CALL FUNCTION 'BAL_DB_SAVE'
  EXPORTING
    i_save_all = abap_true.

12. Use Log in Job

REPORT zlog_in_job.

DATA: go_log TYPE REF TO zcl_application_log.

START-OF-SELECTION.
  " Initialize log
  go_log = NEW zcl_application_log(
    iv_object    = 'ZJOB'
    iv_subobject = 'DAILY'
    iv_extnumber = |Job { sy-datum } { sy-uzeit }|
  ).

  go_log->add_info( 'Job started' ).

  TRY.
      " Processing
      perform_processing( ).
      go_log->add_success( 'Job completed successfully' ).

    CATCH cx_root INTO DATA(lx_error).
      go_log->add_exception( lx_error ).
      go_log->add_error( 'Job ended with error' ).
  ENDTRY.

  " Always save
  go_log->save( ).

END-OF-SELECTION.

13. Call SLG1 Programmatically

" Log display like SLG1
DATA: ls_display_profile TYPE bal_s_prof.

" Standard profile
CALL FUNCTION 'BAL_DSP_PROFILE_STANDARD_GET'
  IMPORTING e_s_display_profile = ls_display_profile.

" Customize settings
ls_display_profile-title    = 'My Log Display'.
ls_display_profile-tree_log = abap_true.   " Tree display

" Display
CALL FUNCTION 'BAL_DSP_LOG_DISPLAY'
  EXPORTING
    i_s_display_profile = ls_display_profile
  EXCEPTIONS
    OTHERS              = 1.

Important Function Modules

Function Module	Description
`BAL_LOG_CREATE`	Create log
`BAL_LOG_MSG_ADD`	Add message
`BAL_DB_SAVE`	Save to DB
`BAL_DB_SEARCH`	Search logs
`BAL_DB_LOAD`	Load logs
`BAL_DB_DELETE`	Delete logs
`BAL_DSP_LOG_DISPLAY`	Display logs

Important Notes / Best Practice

Maintain log objects in SLG0 (don’t hardcode).
Use external number for easy search in SLG1.
Don’t forget COMMIT WORK after BAL_DB_SAVE.
Use hierarchy for clear structuring.
Use context for navigation to documents.
Implement callbacks for detail display.
Use mass logging for performance with many messages.
Regularly clean up old logs (performance).
Use problem class and detail level for filtering.
Combine with Background Jobs for batch logging.