The Microsoft .NET Framework provides several debugging tools that can help you analyze your data processing extension code and locate errors in it. The tool that works best will depend on what you are trying to accomplish. This example uses Visual Studio 2008.
To debug your data processing extension code
Launch Visual Studio 2008, and open your data processing extension project.
Build the project, and deploy your data processing extension assembly and the accompanying .pdb file to the Report Designer. For more information about deployment, see How to: Deploy a Data Processing Extension to Report Designer.
Open a new Report Project in Visual Studio while leaving your data processing extension code open in a separate window of Visual Studio.
Navigate to the window of Visual Studio that contains your data processing extension project and set some break points in your code.
With the data processing extension project window still active, click Attach to Process on the Debug menu.
The Attach to Process dialog opens.
From the list of processes, select the devenv.exe process that corresponds to your Report Project and click Attach.
Define your report data source using the Report Data tab of the Report Project. You will most likely use the generic Query Designer to execute a query against your custom data source. This should invoke the debugger and execute code corresponding to your break points.
Step through your code using the F11 key. For more information about using Visual Studio for debugging, see your Visual Studio documentation.