How to Debug Visual Basic COM DLLs Used in DTS

Debugging Visual Basic (VB) COM DLLs that you use in DTS is easier than it sounds. First, open the DTS Package in the DTS Designer. Then, start the VB Interactive Debugging Editor and open the WebDataFetcher project. Within the VB IDE, you can run the project with a full compile by pressing Ctrl+F5. Running the project with a full compile is a good way to check for blatant syntax errors. The program will highlight in blue any lines that contain syntax errors.

You can also step through the code and inspect how it works or debug errors in the programming logic by pressing F8, which puts the VB IDE in debug mode. The VB IDE will temporarily register the WebDataFetcher project. In debug mode, the VB IDE will stop on the first line of code in the project before it's executed. When you run the DTS Package, the VB IDE isn't in the screen view. After you run the Package, click the VB IDE icon to bring the IDE into view. The program will highlight in yellow the first line of the GetFile function. VB IDE will execute this line next. Each subsequent time you press F8, the VB IDE will execute the present line, move to the next line, and highlight it. You can move the flashing cursor over any variable, such as aURL, then pause, and a window will pop up that contains the value of that variable. If you don't want to step through code, just press F5 and VB IDE will run the rest of the code without stopping. When you want to stop the VB IDE from running in debug mode, click the End item in the Run menu list.