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RAP OData Service Implementation - Lessons Learned

Date: 2025-12-08 Report ID: 003 Subject: Unmanaged RAP OData Service for abapGit Integration Status: Working

Overview

Successfully created a RAP OData V4 service (ZADT_GIT_DEPLOY) that can be deployed and managed entirely via ADT/MCP. This enables future abapGit integration without requiring SAP GUI or manual SEGW projects.

Architecture

┌─────────────────────────────────────────────────────────────┐
│                    OData V4 Service                         │
│              ZADT_GIT_DEPLOY_O4 (SRVB)                     │
└─────────────────────────────────────────────────────────────┘
                            │
┌─────────────────────────────────────────────────────────────┐
│                  Service Definition                         │
│                   ZADT_GIT_DEPLOY (SRVD)                   │
│              expose ZADT_R_GIT_SERVICE as GitService        │
└─────────────────────────────────────────────────────────────┘
                            │
┌─────────────────────────────────────────────────────────────┐
│                 Behavior Definition                         │
│               ZADT_R_GIT_SERVICE (BDEF)                    │
│     unmanaged implementation in class ZCL_ZADT_GIT_SERVICE │
└─────────────────────────────────────────────────────────────┘
                            │
┌─────────────────────────────────────────────────────────────┐
│                  CDS Root Entity                            │
│               ZADT_R_GIT_SERVICE (DDLS)                    │
│            Singleton pattern (ServiceId='SERVICE')          │
└─────────────────────────────────────────────────────────────┘

Key Lessons Learned

1. Handler Class Naming Convention

For unmanaged RAP, the local handler class name must be:

lhc_<alias>

Where <alias> is the entity alias from the BDEF, matching the exact case.

Example:

" BDEF:
define behavior for ZADT_R_GIT_SERVICE alias GitService

" Handler class (in locals_imp):
CLASS lhc_GitService DEFINITION INHERITING FROM cl_abap_behavior_handler.

Wrong patterns that don't work:

  • lhc_gitservice (lowercase) - may work on some systems
  • lhc_zadt_r_git_service (entity name instead of alias)
  • lhc_GITSERVICE (uppercase)

2. Instance Features Require BDEF Declaration

If you implement get_instance_features FOR INSTANCE FEATURES, you MUST declare ( features: instance ) on each action in the BDEF:

" BDEF - Required for instance features:
action ( features: instance ) deploy parameter ... result ...;
action ( features: instance ) getSupportedTypes result ...;

Error without this:

The property "features:instance" is not defined for "ZADT_R_GIT_SERVICE"

3. %control Not Available in All Scenarios

For unmanaged RAP without draft, the %control component is not available in the result structure:

" WRONG - causes activation error:
APPEND VALUE #( %tky = <key>-%tky
                ServiceId = <key>-ServiceId
                %control = VALUE #( ... ) )  " Not available!
  TO result.

" CORRECT:
APPEND VALUE #( %tky = <key>-%tky
                ServiceId = <key>-ServiceId
                LastChanged = lv_ts )
  TO result.

4. Saver Class Naming

The saver class follows a different pattern - it uses the entity name (not alias):

CLASS lsc_zadt_r_git_service DEFINITION INHERITING FROM cl_abap_behavior_saver.

5. Authorization for Actions

For instance actions, you must return authorization for each action in get_instance_authorizations:

METHOD get_instance_authorizations.
  LOOP AT keys ASSIGNING FIELD-SYMBOL(<key>).
    APPEND VALUE #( %tky = <key>-%tky
                    %action-deploy = if_abap_behv=>auth-allowed
                    %action-getSupportedTypes = if_abap_behv=>auth-allowed )
      TO result.
  ENDLOOP.
ENDMETHOD.

6. Feature Control for Actions

Return feature control to enable/disable actions dynamically:

METHOD get_instance_features.
  LOOP AT keys ASSIGNING FIELD-SYMBOL(<key>).
    APPEND VALUE #( %tky = <key>-%tky
                    %action-deploy = if_abap_behv=>fc-o-enabled
                    %action-getSupportedTypes = if_abap_behv=>fc-o-enabled )
      TO result.
  ENDLOOP.
ENDMETHOD.

7. Static vs Instance Actions

We initially tried static actions (no instance binding) but encountered issues with unmanaged RAP. Instance actions on a singleton entity work better:

" BDEF - Instance actions (recommended for unmanaged):
action ( features: instance ) getSupportedTypes result [1] ZADT_A_GIT_TYPES_RESULT;

" NOT recommended - static actions have handler discovery issues:
static action getSupportedTypes result [1] ZADT_A_GIT_TYPES_RESULT;

8. CDS Singleton Pattern

For service-like entities with no real data, use a singleton pattern:

define root view entity ZADT_R_GIT_SERVICE
  as select from I_Language
{
  key cast( 'SERVICE' as abap.char(10) ) as ServiceId,
      @Semantics.systemDateTime.lastChangedAt: true
      tstmp_current_utctimestamp() as LastChanged
}
where Language = $session.system_language

9. OData V4 Action URL Pattern

Instance-bound actions use this URL pattern:

POST /EntitySet('Key')/Namespace.ActionName

Example:

POST /GitService('SERVICE')/com.sap.gateway.srvd.zadt_git_deploy.v0001.getSupportedTypes

10. CSRF Token Required for POST

All modifying operations require X-CSRF-Token:

# 1. Fetch token
curl -H "X-CSRF-Token: Fetch" .../service/ -D -

# 2. Use token in POST
curl -X POST -H "X-CSRF-Token: <token>" .../action

Error Diagnosis

CX_SADL_DUMP_APPL_MODEL_ERROR

This is a wrapper exception. Always check the exception chain in ST22 for the real cause:

  • CX_RAP_HANDLER_NOT_IMPLEMENTED - Handler class not found
  • Check "Involved Entities" to see which entity is affected

Handler Not Implemented

If you see "Handler not implemented; Method: INSTANCE_AUTHORIZATION":

  1. Check handler class name matches alias exactly
  2. Ensure class is activated after BDEF changes
  3. Re-activate BDEF to force metadata refresh

Working Objects

Object Type Description
ZADT_R_GIT_SERVICE DDLS Root CDS entity (singleton)
ZADT_R_GIT_SERVICE BDEF Unmanaged behavior definition
ZCL_ZADT_GIT_SERVICE CLAS Behavior pool with lhc_GitService handler
ZADT_A_GIT_DEPLOY_PARAM DDLS Action input parameter (abstract)
ZADT_A_GIT_TYPES_RESULT DDLS Action result (abstract)
ZADT_GIT_DEPLOY SRVD Service definition
ZADT_GIT_DEPLOY_O4 SRVB V4 service binding

API Endpoints

Base URL: /sap/opu/odata4/sap/zadt_git_deploy_o4/srvd/sap/zadt_git_deploy/0001/

GET  /GitService                    - List entities (singleton)
GET  /GitService('SERVICE')         - Get entity
POST /GitService('SERVICE')/...getSupportedTypes  - Get supported types
POST /GitService('SERVICE')/...deploy             - Deploy repository

Next Steps

  1. Implement deploy action to accept zipped repository
  2. Add exportPackages action to export packages as git-repo format
  3. Integrate with existing abapGit classes if available