References are not allowed in a SAP remote function call

When working with SAP remote function calls, you are trying to make use of references but you should be aware that references are only accessible within the same stack, and in your case, it is not. You are creating a remote function module and here references will not work.

Why References Don't Work in Remote Function Calls

In SAP ABAP, references point to memory locations within the current system's stack. When you make a remote function call (RFC), the function executes on a different system or server, which has its own separate memory space. The reference from your local system cannot point to memory locations on the remote system.

Solution: Use Pass by Value

Instead of using pass by reference, you should use pass by value for your remote function module parameters. This ensures that the actual data values are transmitted across the network to the remote system, rather than memory references that would be invalid on the remote side.

Example

Here's how to define parameters correctly for a remote function module ?

FUNCTION Z_REMOTE_FUNCTION_EXAMPLE.
*"----------------------------------------------------------------------
*"*"Remote-Enabled Function Module:
*"----------------------------------------------------------------------
*"IMPORTING
*"  VALUE(IV_INPUT_PARAM) TYPE STRING
*"EXPORTING
*"  VALUE(EV_OUTPUT_PARAM) TYPE STRING
*"----------------------------------------------------------------------

  " Process the input parameter
  EV_OUTPUT_PARAM = 'Processed: ' && IV_INPUT_PARAM.

ENDFUNCTION.

Notice that all parameters use VALUE() declaration, which enforces pass by value semantics. This ensures the function works correctly when called remotely.

Conclusion

Remote function calls require pass by value parameters because references cannot cross system boundaries. Always use VALUE() declarations in your remote-enabled function modules to ensure proper data transmission across different SAP systems.