An option here might be things like COM and DCOM. Individual, possibly embedded, components and a well defined communications mechanism. Historically the Amiga

An option here might be things like COM and DCOM. Individual, possibly embedded, components and a well defined communications mechanism. Historically the Amiga was quite nice here with systems using AREXX to communicate (but not embed), and Linux/POSIX has things like DBUS for the same (but less flexibly since there's no middleware between the two for coordinating control between systems, the components need to know about one-another directly - kinda).