MQTT-брокер SHEMADEV

# подписка на топик (пакет mosquitto-clients)
mosquitto_sub -h mqtt.shemadev.ru -p 1883 -u ЛОГИН -P 'ПАРОЛЬ' -t 'demo/topic'

# публикация сообщения
mosquitto_pub -h mqtt.shemadev.ru -p 1883 -u ЛОГИН -P 'ПАРОЛЬ' -t 'demo/topic' -m 'hello'

# pip install paho-mqtt
import paho.mqtt.client as mqtt

client = mqtt.Client()
client.username_pw_set("ЛОГИН", "ПАРОЛЬ")
client.connect("mqtt.shemadev.ru", 1883)
client.publish("demo/topic", "hello")

# подписка
client.subscribe("demo/topic")
client.on_message = lambda c, u, m: print(m.topic, m.payload.decode())
client.loop_forever()

// npm install mqtt  (или mqtt.min.js в браузере)
const client = mqtt.connect("ws://mqtt.shemadev.ru:9001", {
  username: "ЛОГИН", password: "ПАРОЛЬ"
});
client.on("connect", () => {
  client.subscribe("demo/topic");
  client.publish("demo/topic", "hello");
});
client.on("message", (topic, msg) => console.log(topic, msg.toString()));

// библиотека PubSubClient (Arduino IDE / PlatformIO)
#include <WiFi.h>
#include <PubSubClient.h>

WiFiClient wifi;
PubSubClient mqtt(wifi);

void setup() {
  WiFi.begin("SSID", "WIFI_PASS");
  while (WiFi.status() != WL_CONNECTED) delay(200);
  mqtt.setServer("mqtt.shemadev.ru", 1883);
  mqtt.connect("esp32", "ЛОГИН", "ПАРОЛЬ");
  mqtt.publish("u/ЛОГИН/hello", "online");
}
void loop() { mqtt.loop(); }