Communication between multiple running processes?

Question

linux

Good day!
There was a problem, there are several running processes:
One of them has user access (Process 1) - for example, the user presses a button.
The second process is also always running (Process 2) - But it constantly performs some tasks and you need to send commands from "process 1", for example:
- suspend,
- status (the result is returned),
- perform a third-party action (after the action has been completed response returned).
Well, for example, the third process, which also works all the time, it is independent and can send commands to both previous ones and receive a response from them and write it to the database.
Prompt how it is better to organize interaction between these processes.
Speed ​​and resources are critical.
Thanks for the replies.

Answer 1

Sockets/named pipes not appropriate?

Answer 2

There are a lot of options for IPC (Inter Process Communication), here they are exhaustively described in Russian.

Answer 3

DBus, still

Answer 4

+1 for UNIX sockets.

Answer 5

Unix Sockets, only the third process communicating with the first is somehow not correct from the point of view of the client-server architecture.

Answer 6

zeroMQ