HOWTO: Debug a Native Code Visual Basic Component in VC++

• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0

SUMMARY

The Visual Basic 5.0 debugger allows you to debug your code at design time before you compile it into an .exe, .dll, or .ocx. If you are debugging Visual Basic-created COM components, you can debug them out-of-process by running multiple projects in the same instance of Visual Basic 5.0, or by running separate instances of Visual Basic 5.0 with the client running in one and the COM component running in the other.

If you want to debug your components after they are compiled, you cannot use the Visual Basic 5.0 debugger because it will only debug them at design time. To debug a compiled Visual Basic component, you will need to use the functionality of the Visual C++ 5.0 debugger. The following are situations when you may need to debug a compiled Visual Basic component:

• if you are creating an ActiveX control for use in a container other than Visual Basic 5.0.
• in an application execution environment such as Microsoft Transaction Server where you are only allowed to run compiled .dlls.
• if you suspect your Visual Basic component is behaving differently at design time than it is compiled.

MORE INFORMATION

The following steps assume that you already have a Visual Basic 5.0-created Standard EXE (.exe), ActiveX DLL (.dll), ActiveX EXE (.exe), or ActiveX Control (.ocx) that you want to debug.

1. In Visual Basic 5.0, open the Visual Basic project that you want to debug. From the File menu, choose Make <YourProject>.exe. Click the Options button and select the Compile tab. Choose Compile to Native Code and Create Symbolic Debug Info. Then select OK, and OK again to compile your component.

2. From the Visual C++ 5.0 File menu, choose Open Workspace. In the Open Workspace dialog, set Files of Type to All files(*.*), and then select your compiled component.

3. Again from the Visual C++ 5.0 File menu, choose Open (not Open Workspace), and open the Visual Basic module (.bas), form (.frm), or class (.cls) that you want to debug. Set break points (F9), watches, step-through instructions, etc., that you would for a normal program. You may also want to display variable information in the debug environment by going to the Visual C++ 5.0 Tools menu, selecting Options, and then selecting the Debug tab. In the Debug tab, place a check next to Display unicode strings.

    then Go, or press the F5 key. When your Visual Basic compiled component
    reaches the line you set a breakpoint on, it will stop in Visual C++
    5.0 and allow you to perform normal debug operations.

    have to specify an exe to debug with. To do this, from the Project menu
    select Settings, and then click the Debug tab. In the Executable for
    debug session text box specify the .exe file that references your .dll.
    Now follow step 4a which will launch your executable and your .dll and
    the Visual C++ 5.0 debugger will come up where you set the breakpoint
    in your .dll.

    this up, select Settings from the Visual C++ 5.0 Project menu, and then
    click the Debug tab. In the Executable for debug session text box,
    specify MTX.EXE. Then, in the Program arguments text box place
    /p:{00000000-0000- 0000-0000- 000000000000} where you would replace
    the 0's with the actual MTS Package ID. The Package ID can be obtained
    by examining the properties of your package in the Transaction Server
    Explorer. Following step 4a above which will launch MTX.EXE and your
    .dll. Now run the base client .exe that makes a call into your COM
    component running under MTS and the Visual C++ 5.0 debugger will come
    up where you set the breakpoint in your .dll.

    IIS runs as an NT Service, you will need to give yourself permission to
    act as part of the operation system. To do this, go to NT
    Administrative Tools and select User Manager. If you are using User
    Manager for Domains in NT Server, make sure you have selected your
    machine name as the Domain from the File menu. Then, choose User Rights
    from the Policies menu. In the User Rights dialog box, place a check
    next to Show Advanced User Rights and select "Act as part of the
    operating system" from the combo box. Click the Add button and type in
    "domainxxx\userxxx" in the text area, or select your username from the
    listbox. Click OK and you should now have the correct privileges. To
    start the debugging session in Visual C++ 5.0, go to the Build menu,
    select Start Debug, then Attach to Process. Place a check next to Show
    System Processes, then select inetinfo and click OK. Now load a client
    .htm or .asp file that will make a call into your ActiveX component. If
    you follow the directions in step 3 above, you should now be able to
    walk through your Visual Basic code.

Note that if the .exe is compiled optimized for size or speed, lines of dead code will be compiled out of the project.

REFERENCES

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Jon Fowler, Microsoft Corporation