Debugging a Web Dynpro
Application 
The SAP NetWeaver Developer Studio provides support when debugging your Web Dynpro applications. By making special settings for the server process of the J2EE Engine and setting breakpoints, you can interrupt the execution of your application and go through it step-by-step.
The following documentation begins by explaining the steps that you need to make in the Developer Studio to activate the debug mode. Next, execute debugging step-by-step using the example of the Welcome Web Dynpro application.
The Welcome application is part of the standard set of example applications contained in the example directory of the Developer Studio (.../SAP/JDT/eclipse/examples). See also: Creating Your First Web Dynpro Application.
Next step: