If the SAP user is defined as type "Dialog" or "Service" (transaction code SU01
) then it's technically feasible to use the SAP GUI (log in with that user and debug).
If the SAP user is defined as type "Communication" or "System" then it's not possible at all.
You can see that as a security measure: if you have a Web Service which runs under a given SAP user, it should not be possible that this user is used for direct SAP GUI usage, to limit possible attacks.
So, I think the only reasonable solution is to use temporarily another SAP user of type "Service" for instance, or change the type of the SAP user, for the duration of the debug.
It's possible to debug another user by selecting the user to debug, either via Eclipse ADT debug properties, or via the ABAP Workbench ABAP Debug Settings, depending on the Integrated Development Environment you are using.
Another solution is, if you have the possibility to change your code temporarily, to add an endless loop (DO. ENDDO.
), debug the running program via the transaction SM50
, menu Administration -> Program -> Debugging, which should open a debug dialog which points at the loop, place the cursor on the line after the loop and press F12 to continue from there.