RAP.md

ABAP RESTful Application Programming Model (RAP) — Complete Guide (Mermaid-safe)

Purpose: A comprehensive developer-focused reference to build and operate RAP business objects with proper transactions, draft handling, validations & determinations, EML, and a clear RAP vs BOPF comparison. Includes copy‑pasteable ABAP snippets and Mermaid diagrams.

What is RAP?
Key Features
Architecture Overview
Transactions, Drafts & Concurrency
Technical Building Blocks
Managed vs Unmanaged Implementation
Validations & Determinations (Code)
Entity Manipulation Language (EML) (Code)
Authorization & Access Control
RAP vs BOPF (Comparison)
Migration Notes (BOPF → RAP)
Worked Example: Book Management BO
References

What is RAP?

The ABAP RESTful Application Programming Model (RAP) is SAP’s modern, cloud‑ready model to build end‑to‑end OData services (Fiori apps and Web APIs) on ABAP. It relies on CDS view entities for semantic data modeling, behavior definitions/implementations for transactional logic, and service definition/binding for protocol exposure (OData V2/V4).

Key Features

End‑to‑end: CDS → Behavior → Service → Fiori/Web API
Transactional: Atomic save sequence with validations, determinations, actions
Draft handling: Edit / Activate / Discard / Resume / Prepare built‑in
Cloud‑ready: Alignment with ABAP Cloud concepts and whitelisted APIs
Typed access: EML for direct ABAP access to RAP BOs
OData V2/V4: Service binding supports both (V4 brings modern features)

Architecture Overview

Components

| Layer | Artifact | Purpose | |---|---|---| | Data | DB tables | Persistency | | Domain | CDS view entities | Semantic model and projections | | Behavior | Behavior definition and Pool | Declare and implement CRUD, validations, determinations, actions, draft | | Exposure | Service definition and binding | Publish as OData V2/V4 | | Programmatic | EML | Typed ABAP access for read/modify/commit |

RAP High‑Level Architecture (Mermaid)

flowchart LR
  subgraph DB[Data Layer]
    T[(Persistence Tables)]
  end
  subgraph ABAP[ABAP Layer]
    CDS[CDS View Entities]
    BEH[Behavior Definition and Pool\nValidations, Determinations, Actions]
    EML[EML – READ/MODIFY/COMMIT]
  end
  subgraph SVC[Service Layer]
    SDEF[Service Definition]
    SBND[Service Binding – OData V2/V4]
  end
  subgraph UI[Client]
    FIORI[Fiori Elements / Web API]
  end

  T <--> CDS
  CDS --> BEH
  EML --> BEH
  CDS --> SDEF --> SBND --> FIORI

Transactions, Drafts & Concurrency

Transactional Buffer and Save Sequence: Changes live in a buffer. COMMIT ENTITIES runs Validations → Determinations → Actions → Persist atomically.
Draft Handling: Enable with draft and get built‑in actions: Edit, Activate (optimized variant available), Discard, Resume, and Prepare.
Optimistic Locking / ETags: Define etag master ... in BDEF and use lock master to protect the lockable subtree.

Save Sequence (Simplified)

sequenceDiagram
  participant C as Client/EML
  participant R as RAP Runtime
  participant H as Behavior Pool
  participant DB as DB

  C->>R: MODIFY ENTITIES
  C->>R: COMMIT ENTITIES
  R->>H: Run validations on save
  H-->>R: Messages / failures
  R->>H: Run determinations
  H-->>R: Derived values
  R->>H: Execute actions (if any)
  R->>DB: Persist atomically
  DB-->>R: OK
  R-->>C: Reported / Failed, ETags

Technical Building Blocks

Behavior Definition (BDEF): Declares operations, field control, validations/determinations, actions, draft, locking, and ETag.
Behavior Pool (ABP): Implements handler methods; can use EML and IN LOCAL MODE when called from within the same pool (develop scenario).
Service Definition/Binding: Clean separation of model vs exposure; supports OData V2/V4.

Managed vs Unmanaged Implementation

Managed: Framework handles CRUD and save; ideal for greenfield—focus on business logic via determinations/validations/actions.
Unmanaged: You implement CRUD/save yourself (for example, wrap legacy BAPIs); ideal for brownfield.
Feature availability: RAP adds OData V4 and modern draft features; see SAP’s matrix comparing RAP, BOPF, and Gateway.

Validations & Determinations (Code)

Below shows a managed + draft root entity ZI_Book with a validation and a determination.

Behavior Definition (BDEF)

managed implementation IN CLASS lhc_Book unique;
WITH draft;

define behavior FOR ZI_Book alias Book
persistent table zbook
lock master
etag master last_changed_at
authorization master ( instance )
{
create;
update;
delete;

FIELD ( mandatory ) title, author;

validation ValidateYear ON save { FIELD published_year; }
determination SetDefaults ON MODIFY { create; }

action Publish result [1] $self;
}

Behavior Implementation (ABP Handler)

CLASS lhc_Book DEFINITION INHERITING FROM cl_abap_behavior_handler.
  PRIVATE SECTION.
  METHODS ValidateYear FOR VALIDATION Book~ValidateYear IMPORTING keys FOR Book.
  METHODS SetDefaults FOR DETERMINATION Book~SetDefaults IMPORTING keys FOR Book.
  METHODS Publish     FOR ACTION      Book~Publish     IMPORTING keys FOR Book RESULT result.
ENDCLASS.

CLASS lhc_Book IMPLEMENTATION.
  METHOD ValidateYear.
    READ ENTITIES OF ZI_Book IN LOCAL MODE
    ENTITY Book
    FIELDS ( published_year )
    WITH CORRESPONDING #( keys )
    RESULT DATA(books).
    
    DATA(current_year) = cl_abap_context_info=>get_system_date( )(1:4).
    
    LOOP AT books ASSIGNING FIELD-SYMBOL(<b>).
      IF <b>-published_year IS INITIAL OR <b>-published_year > current_year.
        APPEND VALUE #( %tky = <b>-%tky
        %msg = new_message_with_text( severity = if_abap_behv_message=>severity-error
        text     = |Published year IS invalid.| ) )
        TO reported-Book.
        APPEND VALUE #( %tky = <b>-%tky ) TO failed-Book.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.
  
  METHOD SetDefaults.
    MODIFY ENTITIES OF ZI_Book IN LOCAL MODE
    ENTITY Book
    UPDATE FIELDS ( created_at created_by )
    WITH VALUE #( FOR key IN keys
    ( %tky = key-%tky
    created_at = cl_abap_context_info=>get_system_time( )
    created_by = cl_abap_context_info=>get_user_technical_name( ) ) ).
  ENDMETHOD.
  
  METHOD Publish.
    result = VALUE #( FOR key IN keys ( %tky = key-%tky ) ).
  ENDMETHOD.
ENDCLASS.

Entity Manipulation Language (EML) (Code)

Create + Commit (typed EML):

MODIFY ENTITIES OF ZI_Book
ENTITY Book
CREATE FROM VALUE #(
( %cid = 'NEW1' title = 'Clean ABAP' author = 'SAP' published_year = 2020 ) )
MAPPED   DATA(mapped)
FAILED   DATA(failed)
REPORTED DATA(reported).

COMMIT ENTITIES RESPONSE OF ZI_Book
FAILED   DATA(failed_commit)
REPORTED DATA(reported_commit).

Execute an Action:

MODIFY ENTITIES OF ZI_Book
ENTITY Book
EXECUTE Publish FROM VALUE #( ( %tky-%key-id = '0000000001' ) )
RESULT DATA(action_result)
FAILED DATA(failed2)
REPORTED DATA(reported2).

Authorization & Access Control

In CDS: @AccessControl.authorizationCheck: #CHECK + DCL to restrict access.
In BDEF: authorization master ( instance ); for drafts, apply feature control to Edit when needed.
For ABAP Cloud, consume only released APIs and BO interfaces.

RAP vs BOPF (Comparison)

| Aspect | RAP | BOPF / ABAP Programming Model for Fiori | |---|---|---| | Service Exposure | Service Definition and Binding (OData V2/V4) | Mostly OData V2 via Gateway | | Transaction Engine | Managed runtime + EML, built‑in draft | BOPF engine; draft via Fiori programming model | | Programming Model | CDS View Entities + Behavior (BDEF/ABP) | CDS + BOPF BO + generated artifacts | | Cloud Readiness | Part of ABAP Cloud; whitelisted APIs | Pre‑cloud; migrate to align | | Concurrency | ETags in BDEF; lock master | BOPF mechanisms | | Developer Access | Typed EML | BOPF Service Manager / APIs | | Feature Matrix | Adds OData V4, modern features | Earlier model |

Migration Notes (BOPF → RAP)

ADT Wizard: Convert CDS‑based BOPF BOs to RAP BOs (simulate/migrate). Enablement may require SAP note/component activation.
Caveat: Wizard may produce BOPF‑based RAP BOs (not fully native RAP) and might not be suitable for ABAP Cloud enablement; remodel to native RAP where feasible.
Why migrate: EML access, OData V2/V4 exposure, RAP events, and strategic alignment with ABAP Cloud.

Worked Example: Book Management BO

CDS View Entity (root)

@EndUserText.label: 'Book'
@AccessControl.authorizationCheck: #CHECK
@Metadata.allowExtensions: TRUE
define root view entity ZI_Book
as SELECT FROM zbook
{
key id              : abap.numc(10),
title           : abap.char(120),
author          : abap.char(60),
published_year  : abap.int4,
created_at      : abap.tims,
created_by      : abap.syuname,
last_changed_at : abap.tims
}

Behavior Definition (minimal)

managed implementation IN CLASS lhc_Book unique;
WITH draft;

define behavior FOR ZI_Book alias Book
persistent table zbook
lock master
etag master last_changed_at
{
create; update; delete; draft;
}

Service Definition

define service ZUI_BOOK {
expose ZI_Book as Book;
}

Bind ZUI_BOOK to OData V4 in Service Binding to generate a Fiori elements UI quickly.

References

ABAP RAP – Help Portal (ABAP Cloud) — https://help.sap.com/docs/abap-cloud/abap-rap/abap-restful-application-programming-model
Learn (Design/Runtime views) — https://help.sap.com/docs/abap-cloud/abap-rap/learn
Entity Manipulation Language (EML) — https://help.sap.com/docs/abap-cloud/abap-rap/entity-manipulation-language-eml
ABAP RESTful Programming Model (Guide/PDF) — https://help.sap.com/doc/7dc426856bc640bf98e9e345a0736cf4/1909%20FPS00/en-US/ABAP_RESTful_Programming_Model_On-Premise_EN.pdf
Draft Actions — https://help.sap.com/docs/abap-cloud/abap-rap/draft-actions and ABAP doc — https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/abenbdl_draft_action.htm
Validations (ABAP Docu) — https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/ABENBDL_VALIDATIONS.html
Getting Started (SAP Community, updated 2024) — https://community.sap.com/t5/technology-blog-posts-by-sap/getting-started-with-the-abap-restful-application-programming-model-rap/ba-p/13420829
Business Object Implementation Types (Managed vs Unmanaged) — https://help.sap.com/docs/abap-cloud/abap-rap/business-object-implementation-types
Feature Matrix: RAP vs BOPF vs Gateway — https://community.sap.com/t5/technology-blog-posts-by-sap/compact-feature-availability-matrix-of-abap-programming-models-rap-vs-bopf/ba-p/13496369
What is RAP? (SAP PRESS blog) — https://blog.sap-press.com/what-is-the-restful-abap-programming-model

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