How to control ESP8266 via server?

Question

Arduino

The situation is that there are several bundles of ESP8266 and ESP12E .
Development is underway in the Arduino IDE.
It is necessary to launch a function on each of the links by an external command. All links, the server and the computer from which the command originates are in the same local Wi-Fi network.
The scheme of work is as follows - a bunch received a command, called a function, sent data to the server.
Now I have sketched a local server and I am sending commands to it, the question is how to make the ESP8266 constantly wait for a command from the server?
The server is written in Flask.

Answer 1

mqtt server