What are windows IPC methods

Question

Question: I have a dll that I can load in another program. Now the dll has access to all data/functions in the other program.

Which technology can I use that now an

Answer 1

COM is the de-facto standard IPC mechanism for Windows-focused applications nowadays.

It allows access across language-barriers, solves the binary interface compatibility problem, does transparent marshalling for you and has different threading models.

sharptooth summarized some facts nicely here.