Starting and Directly Debugging ABAP Programs 
In the ABAP Workbench you can start executable prgorams, function modules, methods, transactions, and background jobs and put them directly under the control of the ABAP Debugger. Follow the procedure below:
In the ABAP Editor (SE38)
On the initial screen:
Enter the program name.
Choose .
In the source text display:
Choose .
In the Object Navigator (SE80):
Select the program, function module, or method to be tested with a double-click.
One of the following options is then available:
In the Object Navigator (SE80):
Select a transaction by double-clicking it.
Choose .
In the transaction maintenance (SE93):
Enter a transaction code.
Choose .
In the job overview (SM37):
Select an inactive job.
Enter jdbg in the command line of the system function bar.
Note
The job and all of its individual steps are executed in a dialog process and you can analyze the job process with the usual debugging tools in the window of the ABAP Debugger. The system field sy-batch has the value X and executing the job in the background is almost completely simulated. You can, for example, explore accesses to the SAP spool system and the evaluation of variants. Some complex features cannot be simulated and checked by you. The special use of specific memory areas in the background job and the fact that a background job does not have any access to the SAP GUI are also included in this.
If a dialog application is canceled with a runtime error then you can switch directly from the short dump display to the ABAP Debugger. In the short dump display choose the Debugger function.
Update debugging can only be triggered from a debugging session. For this, enter the following in the ABAP Debugger window:
.
Debugging can be activated for individual services in the transaction maintenance of the HTTP service tree (SICF). You can create external breakpoints that apply to a specific URL of the incoming HTTP request of to an HTTP request handler class. For further information, see External Debugging.