Out-of-process COM singletons

Question

I am dealing with a single-threaded library (not thread safe) that I want to wrap in a COM out-of-process object to get around its thread non-safety. I need a behavior where each new COM object is instantiated in its own process - some form of out-of-process singleton.

It's been a while since I've been dealing with hardcore COM so I am not sure how to approach this or whether this is at all possible without some trickery.

Answer 1

Call CoRegisterClassObject() with the REGCLS argument set to REGCLS_SINGLEUSE. Beware of the cost, a process is not a cheap operating system object.

There is otherwise no reason why you couldn't ensure that marshaled method calls are thread-safe, just call CoInitializeEx() to ask for an STA. Works as well in a out-of-process server as it does in a in-process server. If you are only doing this to solve a threading problem then definitely favor in-process STA. Message loop required.