I have a C++ application; I would like to expose an API from that application allowing me to control the C++ app from a VB6 app. I want to expose the API through a DLL file. Is this a viable option (is it possible) ? I haven’t been able to find any literature on using DLLs in this way. In fact from what I have read it seems like this is not possible because DLLs create their own new instance for every application they are linked in.

If you have meet theses requirements in an application you built or if your knowledgeable on the subject, please give me a push in the right direction.