RAP (RESTful ABAP Programming Model)

Guide for building transactional applications using the ABAP RESTful Application Programming Model (RAP) in ABAP Cloud.

Workflow

1. Determine the user's goal:

   • Creating a new RAP BO from scratch
   • Adding behavior (actions, validations, determinations) to an existing BO
   • Writing EML statements to consume a RAP BO
   • Troubleshooting RAP-related issues
   • Understanding RAP concepts

2. Identify the scenario:

   • Managed (greenfield) vs. unmanaged (brownfield)
   • Draft-enabled or not
   • Numbering concept: early/late, internal/external/managed
   • Single entity or composition tree (root + children)

3. Guide implementation following the RAP layered architecture:

   • Data modeling (database tables → CDS view entities)
   • Behavior definition (BDEF using BDL)
   • Behavior implementation (ABAP behavior pool)
   • Business service exposure (service definition → service binding)

4. Provide code examples using correct BDL and EML syntax

RAP Architecture Layers

Layer	Artifacts	Purpose
Data Modeling	Database tables, CDS root/child view entities	Data persistence and semantic data model
Behavior Definition	BDEF (.bdef)	Declares transactional behavior (operations, characteristics) using BDL
Behavior Implementation	ABAP behavior pool (BP_*)	Implements business logic in handler/saver classes
Projection	CDS projection views, projection BDEF	Adapts BO for specific service consumers
Business Service	Service definition, service binding	Exposes BO as OData service

Implementation Types

Managed (Greenfield)

• Framework handles transactional buffer and standard CRUD operations automatically
• Only need custom code for non-standard operations (actions, validations, determinations)
• Automatic save handling (can be enhanced with additional save or replaced with unmanaged save)

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

Unmanaged (Brownfield)

• Developer provides transactional buffer and implements all operations
• Used when existing business logic needs to be embedded in RAP

unmanaged implementation in class zbp_r_entity unique;
strict ( 2 );

Behavior Definition (BDL) Quick Reference

Complete BDEF Structure

managed implementation in class zbp_r_root unique;
strict ( 2 );
with draft;

define behavior for ZR_Root alias Root
persistent table zroot_tab
draft table zroot_d
etag master LocalLastChangedAt
lock master
total etag LastChangedAt
authorization master ( global )
late numbering
{
  // Field characteristics
  field ( readonly ) RootUUID, CreatedBy, CreatedAt, LastChangedBy, LastChangedAt;
  field ( mandatory ) Description;
  field ( numbering : managed ) RootUUID;

  // Standard operations
  create;
  update;
  delete;

  // Association to child entity
  association _Child { create; }

  // Actions
  action doSomething result [1] $self;
  static action createFromTemplate parameter ZD_CreateParam result [1] $self;
  internal action recalculate;

  // Validations
  validation validateDescription on save { create; field Description; }

  // Determinations
  determination setDefaults on modify { create; }
  determination calcTotal on modify { field Quantity, Price; }

  // Draft actions
  draft action Resume;
  draft action Edit;
  draft action Activate optimized;
  draft action Discard;
  draft determine action Prepare
  {
    validation validateDescription;
  }

  // Side effects
  side effects
  {
    field Quantity affects field TotalAmount;
    field Price affects field TotalAmount;
    determine action Prepare executed on field Description affects messages;
  }

  // Events
  event created;
  event deleted parameter ZD_DeletedEvent;

  // Mapping
  mapping for zroot_tab corresponding
  {
    RootUUID = root_uuid;
    Description = description;
  }
}

define behavior for ZR_Child alias Child
persistent table zchild_tab
draft table zchild_d
etag master LocalLastChangedAt
lock dependent by _Root
authorization dependent by _Root
{
  field ( readonly ) ChildUUID, RootUUID;
  field ( numbering : managed ) ChildUUID;

  update;
  delete;

  association _Root;

  mapping for zchild_tab corresponding
  {
    ChildUUID = child_uuid;
    RootUUID = root_uuid;
  }
}

Projection BDEF

projection;
strict ( 2 );
use draft;

define behavior for ZC_Root alias Root
{
  use create;
  use update;
  use delete;

  use action doSomething;

  use association _Child { create; }
}

define behavior for ZC_Child alias Child
{
  use update;
  use delete;

  use association _Root;
}

Key BDL Elements

Element	Syntax	Purpose
Managed numbering	field ( numbering : managed ) KeyField;	Framework assigns UUID keys automatically
Early numbering	early numbering	Custom key assignment in interaction phase via FOR NUMBERING handler
Late numbering	late numbering	Key assignment in save sequence via adjust_numbers saver method
Lock master	lock master	Root entity controls pessimistic locking
Lock dependent	lock dependent by _Assoc	Child entity delegates locking to parent
ETag	etag master FieldName	Optimistic concurrency control
Total ETag	total etag FieldName	Required for draft-enabled BOs
Draft	with draft;	Enables draft handling for entire BO
Collaborative draft	with collaborative draft;	Multi-user draft editing
Strict mode	strict ( 2 );	Enables additional BDL syntax checks (use latest version)

ABAP Behavior Pool (ABP)

Handler Class

CLASS lhc_root DEFINITION INHERITING FROM cl_abap_behavior_handler.
  PRIVATE SECTION.

    " Standard operations (unmanaged only)
    METHODS create FOR MODIFY
      IMPORTING entities FOR CREATE Root.

    " Action implementation
    METHODS doSomething FOR MODIFY
      IMPORTING keys FOR ACTION Root~doSomething RESULT result.

    " Validation
    METHODS validateDescription FOR VALIDATE ON SAVE
      IMPORTING keys FOR Root~validateDescription.

    " Determination
    METHODS setDefaults FOR DETERMINE ON MODIFY
      IMPORTING keys FOR Root~setDefaults.

    " Instance feature control
    METHODS get_instance_features FOR INSTANCE FEATURES
      IMPORTING keys REQUEST requested_features FOR Root RESULT result.

    " Instance authorization
    METHODS get_instance_authorizations FOR INSTANCE AUTHORIZATION
      IMPORTING keys REQUEST requested_authorizations FOR Root RESULT result.

ENDCLASS.

CLASS lhc_root IMPLEMENTATION.

  METHOD doSomething.
    " Read current instance data
    READ ENTITIES OF zr_root IN LOCAL MODE
      ENTITY Root
      ALL FIELDS WITH CORRESPONDING #( keys )
      RESULT DATA(entities)
      FAILED failed.

    " Modify instances
    MODIFY ENTITIES OF zr_root IN LOCAL MODE
      ENTITY Root
      UPDATE FIELDS ( Status )
      WITH VALUE #( FOR entity IN entities
        ( %tky = entity-%tky
          Status = 'DONE'
          %control-Status = if_abap_behv=>mk-on ) )
      FAILED failed
      REPORTED reported.

    " Fill result
    result = VALUE #( FOR entity IN entities
      ( %tky = entity-%tky
        %param = entity ) ).
  ENDMETHOD.

  METHOD validateDescription.
    READ ENTITIES OF zr_root IN LOCAL MODE
      ENTITY Root
      FIELDS ( Description ) WITH CORRESPONDING #( keys )
      RESULT DATA(entities).

    LOOP AT entities INTO DATA(entity).
      IF entity-Description IS INITIAL.
        APPEND VALUE #( %tky = entity-%tky ) TO failed-root.
        APPEND VALUE #( %tky = entity-%tky
          %msg = new_message_with_text(
            severity = if_abap_behv_message=>severity-error
            text = 'Description must not be empty' )
          %element-Description = if_abap_behv=>mk-on
        ) TO reported-root.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.

  METHOD setDefaults.
    READ ENTITIES OF zr_root IN LOCAL MODE
      ENTITY Root
      ALL FIELDS WITH CORRESPONDING #( keys )
      RESULT DATA(entities).

    MODIFY ENTITIES OF zr_root IN LOCAL MODE
      ENTITY Root
      UPDATE FIELDS ( Status CreatedAt )
      WITH VALUE #( FOR entity IN entities
        ( %tky = entity-%tky
          Status = 'NEW'
          %control-Status = if_abap_behv=>mk-on ) )
      REPORTED reported.
  ENDMETHOD.

ENDCLASS.

Saver Class

CLASS lsc_root DEFINITION INHERITING FROM cl_abap_behavior_saver.
  PROTECTED SECTION.
    METHODS finalize REDEFINITION.
    METHODS check_before_save REDEFINITION.
    METHODS save_modified REDEFINITION.
    METHODS cleanup REDEFINITION.
    METHODS cleanup_finalize REDEFINITION.
ENDCLASS.

CLASS lsc_root IMPLEMENTATION.
  METHOD finalize.
    " Final calculations before save
  ENDMETHOD.

  METHOD check_before_save.
    " Final consistency checks
  ENDMETHOD.

  METHOD save_modified.
    " Only needed for 'with additional save' or 'with unmanaged save'
    " Raise business events here
    IF create-root IS NOT INITIAL.
      RAISE ENTITY EVENT zr_root~created
        FROM VALUE #( FOR <cr> IN create-root
          ( %key = VALUE #( RootUUID = <cr>-RootUUID ) ) ).
    ENDIF.
  ENDMETHOD.

  METHOD cleanup.
    " Clear transactional buffer
  ENDMETHOD.

  METHOD cleanup_finalize.
    " Rollback finalize changes on failure
  ENDMETHOD.
ENDCLASS.

EML (Entity Manipulation Language) Quick Reference

EML is the ABAP language for programmatically interacting with RAP BOs. Key operations: MODIFY ENTITY (create/update/delete/execute action), READ ENTITIES, COMMIT ENTITIES, ROLLBACK ENTITIES.

• Create: MODIFY ENTITY ... CREATE FIELDS ( ... ) WITH VALUE #( ( %cid = '...' ... ) )
• Read: READ ENTITIES OF ... ALL FIELDS WITH VALUE #( ( key = val ) ) RESULT DATA(result)
• Update: MODIFY ENTITY ... UPDATE FIELDS ( ... ) WITH VALUE #( ( %tky = ... ) )
• Delete: MODIFY ENTITY ... DELETE FROM VALUE #( ( %tky = ... ) )
• Execute Action: MODIFY ENTITY ... EXECUTE actionName FROM VALUE #( ( %tky = ... ) )
• Deep Create: Use CREATE BY \_Assoc with %cid_ref and %target

For full EML syntax with code examples, read references/eml-quick-reference.md.

Draft Handling

• Enabled via with draft; in BDEF header
• Requires separate draft table for each entity
• Draft table must include "%admin": include sych_bdl_draft_admin_inc;
• Draft actions (Edit, Activate, Discard, Resume, Prepare) are implicitly provided
• Use %is_draft component (or %tky which includes it) to distinguish draft vs. active instances

RAP Save Sequence

Phase	Methods Called	Purpose
Early Save	finalize → check_before_save → (on failure: cleanup_finalize)	Ensure data consistency
Late Save	adjust_numbers → save / save_modified → cleanup	Persist data to database

• Early save failures (sy-subrc = 4) return to interaction phase
• Late save is point of no return — either commit succeeds or runtime error

Key BDEF Derived Type Components

Component	Purpose
%cid	Content ID — unique preliminary identifier for new instances
%cid_ref	Reference to a %cid in the same EML request
%key	Primary key fields
%tky	Transactional key (%key + %is_draft + %pid) — recommended
%data	All key and data fields
%control	Flags indicating which fields are provided/requested
%is_draft	Draft indicator (draft-enabled BOs only)
%pid	Preliminary ID (late numbering only)
%target	Target instances for create-by-association
%param	Action/function parameter values

Best Practices

• Always use strict ( 2 ); for new BOs
• Prefer %tky over %key for future-proof code (handles draft/late numbering transitions)
• Always fill %cid in create operations even if not referenced later
• Use IN LOCAL MODE in handler methods to bypass feature controls and authorization checks
• Implement validations for data consistency checks, determinations for calculated fields
• Keep handler methods focused; use ABP auxiliary classes for shared logic
• For managed BOs, only implement handler methods for non-standard operations

References

• SAP ABAP Cheat Sheets — RAP BDL
• SAP ABAP Cheat Sheets — EML
• SAP Help — RAP Development Guide
• SAP Help — BDL Reference
• ABAP Flight Reference Scenario