Summary

 

Chapter 17 - COM Interoperability
bySimon Robinsonet al.
Wrox Press 2002

  

In this chapter, we've looked at interoperability between COM and .NET. We looked at early and late binding to COM components , and generating managed metadata wrappers using TlbImp.exe and Visual Studio .NET.

After some examples of consuming COM components from .NET code, we saw how to release COM objects and use ActiveX controls as we would any other Windows control.

In our exploration of using .NET components from COM clients , we looked at binding to a .NET component, and exporting type libraries with RegAsm.exe and TlbExp.exe . We finished the chapter with a look at platform invocation services, and how .NET can interoperate with unmanaged code in any DLL, such as the Win32 API.

As this chapter has demonstrated, COM and .NET are distinct technologies that can work together if you apply the proper techniques. Using interoperability tools such as TlbImp.exe , RegAsm.exe , and TlbExp.exe , developers can use legacy COM components as building blocks for new .NET applications, and also use .NET components from unmanaged COM clients.

Compared to COM components, assemblies are easier to build, deploy, and maintain. Developers of web applications and programs to be used by organizations internally will find .NET assemblies to be a welcome respite from DLL Hell, and that the simplicity and elegance of the .NET deployment model could be a good enough reason for companies to migrate their existing COM components to .NET.