Visual Basic and Visual C++ register COM classes in the local registry when you build the project. Once registered, these classes are accessible to the Integration Service running on the machine where you compiled the DLL. For example, if you build a project on HOST1, all the classes in the project will be registered in the HOST1 registry and will be accessible to the Integration Service running on HOST1. Suppose, however, that you also want the classes to be accessible to the Integration Service running on HOST2. For this to happen, the classes must be registered in the HOST2 registry.
Visual Basic provides a utility for creating a setup program that can install COM classes on a Windows machine and register these classes in the registry on that machine. While no utility is available in Visual C++, you can easily register the class yourself.