Calling a function in an application A from an application B using its name

Hello

I am sorry if this is a dumb question but is conceivable to call a function in a running application A from another application B using only the know function name and if so how can this be done? I am aware of GetProcAddress and dlsym to find the address of a symbol in a dynamic library that is loaded by the calling application but that does not work here

thanks

Yohan

How about putting the function inside a DLL loaded by both app A and app B?