University of Houston

COM Interoperability, also called COM Interop, provides communication between COM components and .NET applications. COM components can not be directly utilized in .NET applications due to architecture and implementation differences.  In order to overcome these differences, COM Interop provides a wrapper around the COM component called Runtime Callable Wrapper (RCW).  RCW also takes care of data marshalling, exception handling, and object lifetime during interoperation between .NET and COM components.  During interoperability, marshalling overhead may be incurred due to incompatible threading models between the COM component and .NET client.  Another issue during interoperability is the Object lifetime. This may arise due to the holding of COM object resources till they are garbage collected. Unfortunately, none of these issues are handled by the RCW.

In this thesis we proposed and implemented a wrapper to the RCW in Visual C# to handle COM Interop issues.  The wrapper will address the threading model issue by determining the threading model of the COM component. It will then set the same apartment settings for the .NET application.  The wrapper will also take care of the object life time issue for us by releasing the COM object immediately after its use.  To facilitate easy use of this wrapper by the developers we have developed a plug-in wizard for use in Visual Studio .NET 2003.