RAP mit asynchroner Verarbeitung (bgPF) - Background Processing Framework

" ❌ Synchron: Blockiert den Request für Sekunden/Minuten
METHOD generateReport FOR MODIFY
  IMPORTING keys FOR ACTION Travel~generateReport RESULT result.

  " PDF generieren - dauert 5-10 Sekunden
  DATA(lv_pdf) = generate_pdf_for_travel( keys[ 1 ]-%tky ).

  " Email versenden - dauert 2-3 Sekunden
  send_email_with_attachment(
    recipient = get_customer_email( keys[ 1 ]-%tky )
    attachment = lv_pdf
  ).

  " External System benachrichtigen - dauert 1-2 Sekunden
  notify_external_system( keys[ 1 ]-%tky ).

  " → Benutzer wartet 8-15 Sekunden!
ENDMETHOD.

managed implementation in class zbp_i_travel unique;
strict ( 2 );

define behavior for ZI_Travel alias Travel
persistent table ztravel
lock master
authorization master ( instance )
etag master LastChangedAt
{
  create;
  update;
  delete;

  " Synchrone Action - für schnelle Operationen
  action approve result [1] $self;

  " Asynchrone Action - für langläufige Operationen
  action ( execution : background ) generateReport;

  " Asynchrone Action mit Result (Callback)
  action ( execution : background ) processExpenses;

  " Asynchrone Factory Action
  factory action ( execution : background ) createMassBookings [0..*];
}

CLASS lhc_travel DEFINITION INHERITING FROM cl_abap_behavior_handler.
  PRIVATE SECTION.
    METHODS generateReport FOR MODIFY
      IMPORTING keys FOR ACTION Travel~generateReport.

    METHODS processExpenses FOR MODIFY
      IMPORTING keys FOR ACTION Travel~processExpenses.
ENDCLASS.

CLASS lhc_travel IMPLEMENTATION.
  METHOD generateReport.
    " Diese Methode läuft im Background!

    " 1. Travel-Daten laden
    READ ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        ALL FIELDS
        WITH CORRESPONDING #( keys )
      RESULT DATA(lt_travels).

    LOOP AT lt_travels ASSIGNING FIELD-SYMBOL(<travel>).
      " 2. PDF generieren (zeitintensiv)
      DATA(lv_pdf) = NEW zcl_travel_pdf_generator( )->generate(
        travel_id = <travel>-TravelId
      ).

      " 3. PDF in Attachment Service speichern
      zcl_attachment_service=>store(
        object_type = 'TRAVEL'
        object_id   = <travel>-TravelId
        content     = lv_pdf
        filename    = |travel_{ <travel>-TravelId }.pdf|
      ).

      " 4. Status aktualisieren
      MODIFY ENTITIES OF zi_travel IN LOCAL MODE
        ENTITY Travel
          UPDATE FIELDS ( ReportStatus ReportGeneratedAt )
          WITH VALUE #( (
            %tky              = <travel>-%tky
            ReportStatus      = 'G'  " Generated
            ReportGeneratedAt = cl_abap_context_info=>get_system_date( )
          ) ).

      " 5. Event auslösen für weitere Verarbeitung
      RAISE ENTITY EVENT zi_travel~ReportGenerated
        FROM VALUE #( (
          %key          = <travel>-%key
          %param-PdfUrl = |/attachments/travel_{ <travel>-TravelId }.pdf|
        ) ).
    ENDLOOP.
  ENDMETHOD.

  METHOD processExpenses.
    " Expenses verarbeiten und Summen berechnen
    READ ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        ALL FIELDS
        WITH CORRESPONDING #( keys )
      RESULT DATA(lt_travels).

    LOOP AT lt_travels ASSIGNING FIELD-SYMBOL(<travel>).
      " Externe API aufrufen für Wechselkurse
      DATA(lo_http) = cl_web_http_client_manager=>create_by_http_destination(
        cl_http_destination_provider=>create_by_comm_arrangement(
          comm_scenario  = 'Z_CURRENCY_API'
          service_id     = 'Z_CURRENCY_SRV'
        )
      ).

      " Expenses aus Child Entity laden
      READ ENTITIES OF zi_travel IN LOCAL MODE
        ENTITY Travel BY \_Expenses
          ALL FIELDS
          WITH CORRESPONDING #( keys )
        RESULT DATA(lt_expenses).

      " Summe berechnen und konvertieren
      DATA(lv_total) = REDUCE abap_dec15_2(
        INIT sum = 0
        FOR expense IN lt_expenses
        NEXT sum = sum + convert_currency(
          amount   = expense-Amount
          from     = expense-Currency
          to       = <travel>-Currency
        )
      ).

      " Travel aktualisieren
      MODIFY ENTITIES OF zi_travel IN LOCAL MODE
        ENTITY Travel
          UPDATE FIELDS ( TotalExpenses ExpensesProcessedAt )
          WITH VALUE #( (
            %tky                = <travel>-%tky
            TotalExpenses       = lv_total
            ExpensesProcessedAt = cl_abap_context_info=>get_system_date( )
          ) ).
    ENDLOOP.
  ENDMETHOD.
ENDCLASS.

define root view entity ZC_Travel
  provider contract transactional_query
  as projection on ZI_Travel
{
  @UI.lineItem: [
    { position: 10 },
    { type: #FOR_ACTION, dataAction: 'approve', label: 'Genehmigen' },
    { type: #FOR_ACTION, dataAction: 'generateReport', label: 'Report erstellen' }
  ]
  key TravelUUID,

  @UI.fieldGroup: [{ qualifier: 'Status', position: 10 }]
  ReportStatus,

  @UI.fieldGroup: [{ qualifier: 'Status', position: 20 }]
  ReportGeneratedAt
}

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│   Client    │     │  RAP/OData  │     │    bgPF     │
└──────┬──────┘     └──────┬──────┘     └──────┬──────┘
       │                   │                   │
       │  POST /action     │                   │
       │──────────────────>│                   │
       │                   │                   │
       │                   │  Schedule Task    │
       │                   │──────────────────>│
       │                   │                   │
       │  HTTP 202         │                   │
       │<──────────────────│                   │
       │  (Accepted)       │                   │
       │                   │                   │
       │                   │         ┌─────────┴─────────┐
       │                   │         │ Background Worker │
       │                   │         │                   │
       │                   │         │ generateReport()  │
       │                   │         │ ...läuft...       │
       │                   │         │ ...fertig!        │
       │                   │         └───────────────────┘

" Option 1: Status-Feld aktualisieren
MODIFY ENTITIES OF zi_travel IN LOCAL MODE
  ENTITY Travel
    UPDATE FIELDS ( ReportStatus )
    WITH VALUE #( (
      %tky         = <travel>-%tky
      ReportStatus = 'P'  " Processing
    ) ).

" Nach Abschluss
MODIFY ENTITIES OF zi_travel IN LOCAL MODE
  ENTITY Travel
    UPDATE FIELDS ( ReportStatus ReportGeneratedAt )
    WITH VALUE #( (
      %tky              = <travel>-%tky
      ReportStatus      = 'C'  " Completed
      ReportGeneratedAt = cl_abap_context_info=>get_system_date( )
    ) ).

" Option 2: Business Event auslösen
RAISE ENTITY EVENT zi_travel~ReportGenerated
  FROM VALUE #( ( %key = <travel>-%key ) ).

define behavior for ZI_Travel alias Travel
{
  " Asynchrone Action
  action ( execution : background ) generateReport;

  " Events für Statusänderungen
  event ReportGenerated parameter ZA_ReportEvent;
  event ReportFailed parameter ZA_ErrorEvent;
}

define abstract entity ZA_ReportEvent
{
  TravelId  : abap.numc( 8 );
  PdfUrl    : abap.string( 255 );
  Timestamp : timestampl;
}

define abstract entity ZA_ErrorEvent
{
  TravelId     : abap.numc( 8 );
  ErrorCode    : abap.char( 10 );
  ErrorMessage : abap.string( 255 );
}

CLASS zcl_travel_event_handler DEFINITION
  PUBLIC
  CREATE PUBLIC.

  PUBLIC SECTION.
    INTERFACES if_rap_event_handler.
ENDCLASS.

CLASS zcl_travel_event_handler IMPLEMENTATION.
  METHOD if_rap_event_handler~handle_event.
    " Event-Typ prüfen
    CASE io_event->get_event_name( ).
      WHEN 'REPORTGENERATED'.
        " Payload lesen
        DATA(ls_payload) = io_event->get_payload( ).
        DATA(lv_travel_id) = ls_payload-TravelId.
        DATA(lv_pdf_url) = ls_payload-PdfUrl.

        " Kunden per Email benachrichtigen
        DATA(lo_travel) = NEW zcl_travel_service( ).
        DATA(ls_travel) = lo_travel->get_by_id( lv_travel_id ).

        NEW zcl_email_service( )->send(
          to      = ls_travel-CustomerEmail
          subject = |Ihr Reisebericht ist verfügbar|
          body    = |Der Report für Ihre Reise ist fertig: { lv_pdf_url }|
        ).

      WHEN 'REPORTFAILED'.
        " Administrator benachrichtigen
        DATA(ls_error) = io_event->get_payload( ).

        NEW zcl_notification_service( )->notify_admin(
          subject = |Report-Generierung fehlgeschlagen|
          message = |Travel { ls_error-TravelId }: { ls_error-ErrorMessage }|
        ).
    ENDCASE.
  ENDMETHOD.
ENDCLASS.

" In der Service Binding oder über die Event Handler Registry
CLASS zcl_event_handler_registry DEFINITION
  PUBLIC
  FINAL.

  PUBLIC SECTION.
    CLASS-METHODS register_handlers.
ENDCLASS.

CLASS zcl_event_handler_registry IMPLEMENTATION.
  METHOD register_handlers.
    " Registrierung erfolgt deklarativ über Annotation
    " @EventHandler für entsprechende Events
  ENDMETHOD.
ENDCLASS.

METHOD generateReport.
  TRY.
      " Externe API aufrufen
      DATA(lo_http) = cl_web_http_client_manager=>create_by_http_destination(
        cl_http_destination_provider=>create_by_comm_arrangement(
          comm_scenario = 'Z_PDF_SERVICE'
        )
      ).

      DATA(lo_request) = lo_http->get_http_request( ).
      lo_request->set_uri_path( '/generate' ).

      DATA(lo_response) = lo_http->execute( if_web_http_client=>post ).
      DATA(lv_status) = lo_response->get_status( )-code.

      CASE lv_status.
        WHEN 200 TO 299.
          " Erfolg - PDF verarbeiten
          process_pdf_response( lo_response ).

        WHEN 429 OR 503.
          " Transient Error - Retry durch Framework
          " Werfe retryable Exception
          RAISE EXCEPTION TYPE cx_bgpf_retryable
            EXPORTING
              textid = cx_bgpf_retryable=>service_temporarily_unavailable.

        WHEN OTHERS.
          " Permanenter Fehler - Kein Retry
          RAISE ENTITY EVENT zi_travel~ReportFailed
            FROM VALUE #( (
              %key              = keys[ 1 ]-%key
              %param-ErrorCode  = |HTTP_{ lv_status }|
              %param-ErrorMessage = lo_response->get_text( )
            ) ).
      ENDCASE.

    CATCH cx_http_dest_provider_error
          cx_web_http_client_error INTO DATA(lx_http).
      " Netzwerkfehler - normalerweise transient
      RAISE EXCEPTION TYPE cx_bgpf_retryable
        EXPORTING
          previous = lx_http.
  ENDTRY.
ENDMETHOD.

" Retry-Verhalten kann über Annotations gesteuert werden
define behavior for ZI_Travel alias Travel
{
  " Action mit spezifischer Retry-Konfiguration
  action ( execution : background, retries : 5, delay : 120 )
    processLargeDataset;
}

METHOD processAllOpenTravels.
  " Alle offenen Reisen laden
  SELECT * FROM ztravel
    WHERE status = 'O'
    INTO TABLE @DATA(lt_travels).

  " Parallel verarbeiten durch Batch-Scheduling
  DATA(lv_batch_size) = 100.
  DATA(lv_offset) = 0.

  WHILE lv_offset < lines( lt_travels ).
    " Batch extrahieren
    DATA(lt_batch) = VALUE ty_travel_tab(
      FOR i = lv_offset WHILE i < lv_offset + lv_batch_size
      ( lt_travels[ i ] )
    ).

    " Background Task für jeden Batch
    cl_bgpf_process_api=>schedule(
      EXPORTING
        iv_process_name = 'Z_PROCESS_TRAVEL_BATCH'
        it_parameters   = VALUE #(
          ( name = 'BATCH_DATA' value = cl_abap_conv_out_ce=>create( )->write( lt_batch ) )
        )
    ).

    lv_offset = lv_offset + lv_batch_size.
  ENDWHILE.
ENDMETHOD.

CLASS zcl_travel_batch_processor DEFINITION
  PUBLIC
  FINAL
  CREATE PUBLIC.

  PUBLIC SECTION.
    INTERFACES if_bgpf_process.
ENDCLASS.

CLASS zcl_travel_batch_processor IMPLEMENTATION.
  METHOD if_bgpf_process~execute.
    " Parameter auslesen
    DATA(lv_batch_data) = it_parameters[ name = 'BATCH_DATA' ]-value.
    DATA lt_travels TYPE TABLE OF ztravel.

    " Daten deserialisieren
    cl_abap_conv_in_ce=>create( input = lv_batch_data )->read(
      IMPORTING data = lt_travels
    ).

    " Batch verarbeiten
    LOOP AT lt_travels ASSIGNING FIELD-SYMBOL(<travel>).
      TRY.
          process_single_travel( <travel> ).
        CATCH cx_root INTO DATA(lx_error).
          " Fehler loggen, aber fortfahren
          log_error( travel = <travel> error = lx_error ).
      ENDTRY.
    ENDLOOP.

    " Ergebnis
    rv_result = if_bgpf_process=>c_result-success.
  ENDMETHOD.
ENDCLASS.

CLASS zcl_bgpf_logger DEFINITION.
  PUBLIC SECTION.
    METHODS log_start
      IMPORTING iv_action TYPE string
                iv_object_id TYPE string.

    METHODS log_success
      IMPORTING iv_action TYPE string
                iv_object_id TYPE string
                iv_details TYPE string OPTIONAL.

    METHODS log_error
      IMPORTING iv_action TYPE string
                iv_object_id TYPE string
                ix_error TYPE REF TO cx_root.

  PRIVATE SECTION.
    DATA mo_log TYPE REF TO if_bali_log.
ENDCLASS.

CLASS zcl_bgpf_logger IMPLEMENTATION.
  METHOD log_start.
    mo_log = cl_bali_log=>create( ).
    mo_log->set_header(
      header = cl_bali_header_setter=>create(
        object      = 'Z_BGPF'
        subobject   = iv_action
        external_id = iv_object_id
      )
    ).

    mo_log->add_item(
      item = cl_bali_free_text_setter=>create(
        severity = if_bali_constants=>c_severity_information
        text     = |Background Task gestartet: { iv_action }|
      )
    ).

    cl_bali_log_db=>get_instance( )->save_log( log = mo_log ).
  ENDMETHOD.

  METHOD log_success.
    mo_log->add_item(
      item = cl_bali_free_text_setter=>create(
        severity = if_bali_constants=>c_severity_status
        text     = |Erfolgreich abgeschlossen: { iv_details }|
      )
    ).

    cl_bali_log_db=>get_instance( )->save_log( log = mo_log ).
  ENDMETHOD.

  METHOD log_error.
    mo_log->add_item(
      item = cl_bali_exception_setter=>create(
        severity  = if_bali_constants=>c_severity_error
        exception = ix_error
      )
    ).

    cl_bali_log_db=>get_instance( )->save_log( log = mo_log ).
  ENDMETHOD.
ENDCLASS.

" Task-Status abfragen
DATA(lo_monitor) = cl_bgpf_process_api=>get_monitor( ).

DATA(lt_tasks) = lo_monitor->get_tasks(
  iv_process_name = 'Z_GENERATE_REPORT'
  iv_from_date    = sy-datum - 7
  iv_to_date      = sy-datum
).

LOOP AT lt_tasks INTO DATA(ls_task).
  WRITE: / ls_task-task_id,
           ls_task-status,
           ls_task-started_at,
           ls_task-completed_at.
ENDLOOP.

" Fehlgeschlagene Tasks
DATA(lt_failed) = lo_monitor->get_failed_tasks(
  iv_process_name = 'Z_GENERATE_REPORT'
).

LOOP AT lt_failed INTO DATA(ls_failed).
  WRITE: / |Task { ls_failed-task_id } fehlgeschlagen: { ls_failed-error_message }|.
ENDLOOP.

" ✅ Idempotent: Prüft ob schon verarbeitet
METHOD generateReport.
  READ ENTITIES OF zi_travel IN LOCAL MODE
    ENTITY Travel
      FIELDS ( ReportStatus )
      WITH CORRESPONDING #( keys )
    RESULT DATA(lt_travels).

  LOOP AT lt_travels ASSIGNING FIELD-SYMBOL(<travel>).
    " Bereits generiert? Skip!
    IF <travel>-ReportStatus = 'C'.
      CONTINUE.
    ENDIF.

    " Report generieren...
  ENDLOOP.
ENDMETHOD.

" Große Datenmengen in Chunks verarbeiten
METHOD processMassData.
  DATA(lv_chunk_size) = 1000.
  DATA(lv_processed) = 0.

  SELECT * FROM zlarge_table
    INTO TABLE @DATA(lt_chunk)
    UP TO @lv_chunk_size ROWS
    OFFSET @lv_processed.

  WHILE lt_chunk IS NOT INITIAL.
    process_chunk( lt_chunk ).
    lv_processed = lv_processed + lines( lt_chunk ).

    " Checkpoint für lange Operationen
    IF lv_processed MOD 10000 = 0.
      COMMIT WORK.
    ENDIF.

    SELECT * FROM zlarge_table
      INTO TABLE @lt_chunk
      UP TO @lv_chunk_size ROWS
      OFFSET @lv_processed.
  ENDWHILE.
ENDMETHOD.

" Bei Fehler: Status und Event setzen
TRY.
    " Verarbeitung...
  CATCH cx_root INTO DATA(lx_error).
    " Status auf Error setzen
    MODIFY ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        UPDATE FIELDS ( ProcessingStatus ErrorMessage )
        WITH VALUE #( (
          %tky             = keys[ 1 ]-%tky
          ProcessingStatus = 'E'  " Error
          ErrorMessage     = lx_error->get_text( )
        ) ).

    " Error-Event für Monitoring
    RAISE ENTITY EVENT zi_travel~ProcessingFailed
      FROM VALUE #( (
        %key                 = keys[ 1 ]-%key
        %param-ErrorMessage  = lx_error->get_text( )
      ) ).
ENDTRY.

" ❌ Falsch: COMMIT in RAP-Handler
METHOD processData.
  COMMIT WORK.  " Nicht erlaubt!
ENDMETHOD.

" ✅ Richtig: Transaktionssteuerung dem Framework überlassen
" bgPF macht automatisch COMMIT nach erfolgreicher Ausführung