I am studying COM. I think the best way to get a thorough understanding of COM is write one without any COM framework such as ATL. I have written a COM server in raw C++, and now I want to write one in plain raw C. How could I do this? Is there any tutorial?
Many thanks.
Don Box's book Essential COM is one of the best that explains everything about COM from the ground up. Recommended.
COM, however, is decade old technology that's a heck of a lot of work to do in C, and Don Box (previously considered one of the experts) doesn't even touch it anymore. Take what you will from that.
Writing COM servers in C is not impossible. It is just that COM code is already beefy, it will be quite a bit beefier in C since you don't get help from the built-in v-table support that a compliant C++ compiler generates. Or a class library like ATL. You have to create your own.
A good source for COM example code written in C is the WINE project. For example, the implementation of the IGlobalInterfaceTable interface. Note the GITClassFactoryVtbl in that code, that's the interface dispatch table for the class factory, and StdGlobalInterfaceTableImpl_Vtbl, the dispatch table for IGlobalInterfaceTable.
Not so sure that this will give you a deeper insight in COM programming. It is unlikely you'll ever write a real server like this. Have you written an out-of-process server yet?