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Debugging Components Written in Visual C++

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When you are ready to debug the COM+ functionality in your Microsoft Visual C++ components, you can configure Visual C++ project or the Component Services administrative tool to launch the debugger. If you are using Visual C++, you can debug with a remote client using OLE RPC and just-in-time (JIT) debugging. If you are unable to run your client under the debugger or if the client is running on another machine, you can use the COM+ Launch in debugger setting. You will find this in the Component Services administrative tool as a check box on the Advanced tab of the COM+ application Properties dialog box.

When you are finished debugging, you should shut down the COM+ applications you are debugging. If a server process is left running, you might get an error message the next time you try to build a DLL when the existing DLL is still loaded in memory. To shut down a COM+ application, right-click the application in the console tree and then click Shut down.

Note

If you are using transactions, you might also want to increase the transaction time-out, which defaults to 60 seconds. You can also specify a value of 0, effectively specifying an infinite transaction time-out period. Using the Component Services administrative tool, change the transaction time-out setting on the Options tab of the My Computer Properties window.

 

Debugging Server Application Components with Visual C++

When debugging COM+ server applications, you may want to debug remote calls by loading both the client and the server application into the debugger. With Visual C++, you can debug remote calls to your components through the just-in-time (JIT) and OLE RPC settings. The JIT setting causes the compiled component to start the Visual C++ debugger when an error occurs; the OLE RPC setting enables the debugger to step from client to component as you step through your code.

When these features are enabled, you can start your client under the debugger. When the client makes a call to your component, the debugger will step into the component's code in the server process, even if the server is on a different computer on the network. A debugging session is automatically started on the server computer if necessary. Similarly, single stepping past the return statement in the component's code will return debugging to the next statement in the client's code.

Note

You may be able to save a few steps by using the COM+ Launch in debugger setting. This allows you to specify the Visual C++ (or other) debugger without having to make special debug settings in the Visual C++ environment. You will find this in the Component Services administrative tool as a check box on the Advanced tab of the COM+ application Properties dialog box. For more information, see "Debugging Without Visual C++" in this topic.

 

When the COM+ application containing your component is a server application, you must begin by shutting down the application using the Component Services administrative tool. To do this, right-click the COM+ application in the console tree and then click Shut down.

To enable RPC debugging in Visual C++

  1. In Visual C++, on the Tools menu, click Options.

  2. In the Options dialog box, on the Debug tab, select the OLE RPC debugging and Just-in time debugging check boxes.

  3. Click OK.

To begin debugging, start your client project in the debugger.

You can also debug your component without launching your client in the debugger. In this case, your component must launch the debugger on its own. To do this, your component project must specify an executable for the debug session, along with the COM+ application ID.

To enable a server application component to launch the Visual C++ debugger

  1. On the Project menu, click Settings.

  2. In the Project Settings dialog box, in the Settings For box, select Win32 Debug.

  3. On the Debug tab, in the Category box, select General.

  4. In the Executable for debug session box, enter the fully qualified path for Dllhost.exe, followed by an argument specifying the application ID of the COM+ application containing the component.

    Note

    Using the Component Services administrative tool, you will find the application ID on the General tab of the COM+ application's Properties dialog box. Following is an example:

     

    Note

    C:\Winnt\System32\Dllhost.exe /ProcessID:{applicationID}

     

  5. Click OK.

You can now set breakpoints, start the debugger, and begin making calls to your component.

Debugging Library Application Components with Visual C++

To debug components in a library application, you must configure the client's project because the client's process will host the library application.

To enable library application debugging with Visual C++

  1. In Visual C++, on the Project menu, click Settings.

  2. In the Project Settings dialog box, in the Settings For box, click Win32 Debug.

  3. On the Debug tab, in the Category box, click Additional DLLs.

  4. In the Modules list, add the component DLLs in your library application. This allows you to set breakpoints before your DLL is actually loaded.

  5. Click OK.

Debugging Without Visual C++

Whether or not you are using Visual C++ for debugging, you can use the Launch in debugger setting to specify the debugger in which your components should run.

To specify a debugger from the Component Services administrative tool

  1. In the console tree, select the COM+ library application containing the components you wish to debug.

  2. Right-click the application, and then click Properties.

  3. In the application's Properties dialog box, click the Advanced tab.

  4. Under Debugging, select the Launch in debugger check box.

  5. In the Debugger path box, enter path to the debugger you want to use. You can also click Browse to locate the debugger. Following is an example: C:\Winnt\System32\Ntsd.exe.

  6. Click OK.

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