process - How do you stream data into the STDIN of a program from different local/remote processes in Python?

Question

Standard streams are associated with a program. So, suppose there is a program already running in some way (I don't care how or in what way). The goal is to create pipes to the STDIN of the program from different processes (or programs) that run either locally or remotely and stream data into it asynchronously.

Available information is (1) the host address and (2) the pid of the program only. How does one implement both cases in Python in this case?

Edit: I should have mentioned this presupposition. The intended operating system is Linux with a (fairly) recent kernel.

Answer 1

This isn't portable, but on many Linux systems, you can write to

/proc/$PID/fd/0

I think this may be one of a very limited number of potentially complicated options if you don't have any other control over the remote process.