Module 25: RFC, BAPI & Integration

RFC (Remote Function Call) is SAP’s core technology for communication between SAP systems and external systems.
BAPIs build on RFC to provide stable, business-level APIs.

This module is essential for system integration, interfaces, and enterprise landscapes.

1. What is RFC?

Definition

RFC allows a function module in one system to be called remotely from another system or external application.

Key Characteristics

Synchronous or asynchronous
Secure communication
Transaction-aware
Widely used across SAP

SAP Integration Backbone

RFC is the foundation for BAPIs, ALE, IDocs, and many SAP interfaces.

2. RFC Types

SAP supports multiple RFC types, each for different integration needs.

2.1 Synchronous RFC (sRFC)

Caller waits for response
Immediate result
Most commonly used

CALL FUNCTION 'Z_GET_DATA'
  DESTINATION 'RFC_DEST'
  IMPORTING
    ev_result = lv_result.

Use Case

Real-time data retrieval and validation.

2.2 Asynchronous RFC (aRFC)

Caller does not wait
Fire-and-forget
No guaranteed delivery

CALL FUNCTION 'Z_PROCESS_DATA'
  STARTING NEW TASK lv_task
  DESTINATION 'RFC_DEST'.

Limitation

No built-in confirmation or rollback.

2.3 Transactional RFC (tRFC)

Ensures exactly-once execution
Used for reliable data transfer

CALL FUNCTION 'Z_SEND_DATA'
  IN BACKGROUND TASK
  DESTINATION 'RFC_DEST'.
COMMIT WORK.

Reliability

tRFC ensures data is processed once and only once.

2.4 Queued RFC (qRFC)

Extension of tRFC
Preserves execution order
Uses queues

Typical Use Case

Sequential processing like financial postings.

3. Remote Enabled Function Modules

What Makes a Function Module RFC-Enabled?

Attribute: Remote-Enabled Module
No GUI statements
No COMMIT WORK inside
Serializable parameters only

FUNCTION z_get_customer_data.
*"  IMPORTING iv_custid TYPE kunnr
*"  EXPORTING es_customer TYPE zcust
ENDFUNCTION.

RFC Restrictions

RFC function modules must be stateless and UI-free.

4. BAPI Standards (Very Important)

What is a BAPI?

A BAPI (Business Application Programming Interface) is:

A standardized RFC
Business-object oriented
Stable and upgrade-safe

SAP Contract

SAP guarantees backward compatibility for released BAPIs.

4.1 BAPI Naming & Structure

Typical BAPI structure:

BAPI_<OBJECT>_<ACTION>

Example:

BAPI_SALESORDER_CREATEFROMDAT2

4.2 Standard BAPI Pattern

CALL FUNCTION 'BAPI_SALESORDER_CREATEFROMDAT2'
  EXPORTING
    order_header_in = ls_header
  TABLES
    order_items_in  = lt_items
    return          = lt_return.

4.3 RETURN Table (Mandatory)

The RETURN table:
Contains success, warning, error messages
Must always be checked

READ TABLE lt_return
  WITH KEY type = 'E'
  TRANSPORTING NO FIELDS.

Golden Rule

Never ignore the BAPI RETURN table.

5. Commit Handling in BAPIs

Why BAPIs Don’t Commit Automatically

BAPIs do not perform COMMIT WORK internally to allow:

Logical Unit of Work control
Transaction bundling

5.1 Explicit Commit

CALL FUNCTION 'BAPI_TRANSACTION_COMMIT'
  EXPORTING
    wait = abap_true.

5.2 Rollback on Error

CALL FUNCTION 'BAPI_TRANSACTION_ROLLBACK'.

Correct Flow

Call BAPI
Check RETURN
Commit or Rollback

Error Handling in RFC & BAPI 6.1 RFC Error Handling CALL FUNCTION 'Z_REMOTE_FUNC' DESTINATION 'RFC_DEST' EXCEPTIONS system_failure = 1 communication_failure = 2.

6.2 BAPI Error Handling

Use RETURN table

Use MESSAGE ID/NUMBER

Log errors (SLG1)

Production Best Practice

Always log RFC/BAPI errors using Application Logs.

7. RFC vs BAPI vs OData – Comparison

Aspect	RFC	BAPI	OData
Full Form	Remote Function Call	Business Application Programming Interface	Open Data Protocol
Primary Purpose	Technical remote function execution	Business-level, stable SAP APIs	REST-based data & business services
Technology	ABAP Function Modules	RFC-based standardized FMs	HTTP / REST / JSON
Protocol	SAP RFC protocol	SAP RFC protocol	HTTP(S)
Communication Type	SAP ↔ SAP / External (via connectors)	SAP ↔ SAP / External	SAP ↔ Any (web, mobile, cloud)
Stateless	Yes	Yes	Yes
UI Friendly	❌	❌	✅
Used by UI5 / Fiori	❌	❌	✅
CRUD Support	Custom	Business-specific	Native (GET, POST, PUT, DELETE)
Data Format	ABAP structures	ABAP structures	JSON / XML
Versioning Support	❌	Limited	✅ (service versions)
Security	SAP authorizations	SAP authorizations	OAuth / SAP auth / JWT
Performance	High (binary)	High	Medium (HTTP overhead)
Transaction Handling	Explicit	Explicit (`BAPI_TRANSACTION_COMMIT`)	Stateless (per request)
Error Handling	Exceptions	RETURN table	HTTP status + error payload
Upgrade Safety	❌ (custom RFCs)	✅ (released BAPIs)	✅
Internet Accessible	❌	❌	✅
Modern SAP Direction	⚠️ Limited	⚠️ Maintenance & core	✅ Strategic
Typical Use Cases	System-to-system calls	Business object operations	UI, APIs, cloud integration

7.1 When to Use What (Decision Guide)

✅ Use RFC when:

SAP ↔ SAP technical integration
Internal system calls
High performance required
No UI or internet exposure

::: Calling a utility function from another SAP system. :::

✅ Use BAPI when:

Performing business operations
Upgrade safety is required
Standard SAP object manipulation
ECC / S/4 core integrations

::: Creating Sales Orders, Purchase Orders, Goods Movements. :::

✅ Use OData when:

UI5 / Fiori applications
Cloud or external integrations
REST-based APIs
RAP-based developments

::: Fiori app consuming Sales Order data. :::

7.2 Modern SAP Recommendation (S/4HANA)

Internal SAP logic        → Classes / CDS
System-to-system (SAP)   → BAPI
Modern UI / APIs         → OData (RAP)
Legacy integrations      → RFC

8. Common Integration Pitfalls

Avoid These

COMMIT WORK inside RFC FM
Ignoring RETURN messages
Using SELECT directly instead of BAPIs
Hard-coded RFC destinations
Missing authorization checks

9. Interview-Grade Explanation

Q: How do you design a reliable SAP integration?

Answer:

I use the appropriate RFC type based on reliability and sequencing needs, prefer released BAPIs for business operations, handle errors via RETURN tables and exceptions, control commits explicitly, and ensure logging and restartability.

This Answer Works

This shows real integration experience, not textbook knowledge.

10. Summary

RFC enables SAP-to-SAP and external communication
Different RFC types serve different reliability needs
Remote-enabled function modules are stateless
BAPIs are standardized, stable APIs
Explicit commit handling is mandatory
Robust error handling is critical

11. Practice Exercises

Create an RFC-enabled function module.
Call it synchronously from another system.
Use a BAPI and handle RETURN messages.
Implement explicit commit/rollback logic.
Compare sRFC vs tRFC use cases.

12. What’s Next?

➡️ Module 26: OData Services (ABAP Backend)

Learning Tip

Strong RFC & BAPI knowledge is mandatory for enterprise ABAP developers.

1. What is RFC?​

Definition​

Key Characteristics​

2. RFC Types​

2.1 Synchronous RFC (sRFC)​

2.2 Asynchronous RFC (aRFC)​

2.3 Transactional RFC (tRFC)​

2.4 Queued RFC (qRFC)​

3. Remote Enabled Function Modules​

4. BAPI Standards (Very Important)​

4.1 BAPI Naming & Structure​

4.2 Standard BAPI Pattern​

4.3 RETURN Table (Mandatory)​

5. Commit Handling in BAPIs​

5.1 Explicit Commit​

5.2 Rollback on Error​

7. RFC vs BAPI vs OData – Comparison​

7.1 When to Use What (Decision Guide)​

7.2 Modern SAP Recommendation (S/4HANA)​

8. Common Integration Pitfalls​

9. Interview-Grade Explanation​

Q: How do you design a reliable SAP integration?​

10. Summary​

11. Practice Exercises​

12. What’s Next?​