¶ Debugging ABAP Web Services and RFCs
Subject: SAP-ABAP (Advanced Business Application Programming)
ABAP Web Services and Remote Function Calls (RFCs) are essential components for integrating SAP systems with external applications and enabling distributed business processes. Despite their importance, debugging these interfaces can be challenging due to their asynchronous nature, network dependencies, and complex call stacks.
This article provides a practical guide for ABAP developers on debugging ABAP Web Services and RFCs, with tips and techniques to efficiently identify and resolve issues in SAP environments.
¶ Understanding ABAP Web Services and RFCs
- ABAP Web Services allow SAP to expose function modules, classes, or BAPIs over SOAP or REST protocols.
- Remote Function Calls (RFCs) enable synchronous or asynchronous communication between SAP systems or between SAP and external systems.
Both technologies use the SAP NetWeaver stack and rely on the ABAP runtime but involve different communication layers.
¶ Challenges in Debugging Web Services and RFCs
- Calls often cross system boundaries.
- Processing may happen in background work processes.
- Complex payload structures (XML/JSON).
- Multiple layers: HTTP, SOAP, ABAP runtime.
- Asynchronous callbacks and error handling.
- Identify the service handler: function module, method, or class implementing the web service.
- Place breakpoints in the ABAP code where processing occurs.
- For synchronous calls, use the classic debugger by triggering the web service call (e.g., from SOAP UI or external client).
- For asynchronous calls, ensure the background process triggers the breakpoint (use external debugging if necessary).
- Enable external debugging for your user via SE37 / SE80 or /H command in the ABAP GUI.
- When the web service is called, SAP waits for the debugger to attach.
- This is essential for debugging calls from external systems.
¶ 3. Analyze HTTP and SOAP Requests
- Use transaction SICF to locate and test the service endpoint.
- Use SOAMANAGER to review the Web Service configuration.
- Enable HTTP trace via transaction SMICM → Goto → Trace → HTTP.
- Use external tools like SOAP UI or Postman to test requests and observe raw XML messages.
¶ 4. Check Logs and Error Messages
- Review application logs with transaction SLG1 (Application Log).
- Check SM21 for system logs.
- Use ST22 to analyze dumps caused during service execution.
- For web services, check IWFND/ IWBEP error logs if using OData.
- Place breakpoints in the called function module or method.
- Initiate the RFC call from the calling system or client.
- Use external debugging if the RFC is called from another system.
- Debugger will stop at the breakpoint during execution.
- Asynchronous RFCs run in background work processes, so standard breakpoints won’t stop the debugger.
- Use external debugging by enabling debugging for the user that executes the RFC.
- Alternatively, add BREAK-POINT ID statements with a unique ID and start the debugger manually when triggered.
BREAK-POINT ID 'RFCDBG'.
- Set external breakpoints by transaction SE37 or SE80 with “External Debugging” option.
- Background RFCs execute asynchronously in jobs.
- Debug by setting breakpoints and starting the background job in debug mode.
- Use transaction SM50 or SM66 to monitor work processes.
- Attach debugger to the relevant work process manually.
- Use trace tools like SAT or ST05 (SQL trace) to identify performance issues.
- Utilize transaction SWO1 and SWDD to understand workflow-related RFCs or services.
- Enable detailed logging in the web service or RFC wrapper for better insight.
- Always clean up breakpoints and debugging settings after troubleshooting.
- Open the RFC function module in SE37.
- Set a breakpoint at the start of the module.
- In the calling system, trigger the RFC.
- When execution reaches the breakpoint, the debugger opens.
- Step through code, check variables, and analyze flow.
Debugging ABAP Web Services and RFCs requires familiarity with SAP’s debugging tools, knowledge of external communication protocols, and understanding of SAP’s runtime behavior. By combining breakpoints, external debugging, trace tools, and log analysis, ABAP developers can effectively troubleshoot and resolve issues in integration scenarios, ensuring smooth and reliable cross-system communications.