Universitas ASA Indonesia

Program Studi: Teknologi Informasi
Mata Kuliah: Internet of Things
SKS: 4 (2 teori, 2 praktikum)
Dosen Pengampu: Istiqomah Sumadikarta, S.T., M.Kom.

Beranda Mundur Maju

Pertemuan 12: MQTT (Message Queuing Telemetry Transport)

Tujuan Pembelajaran

Memahami konsep dasar MQTT dan sejarahnya.
Menjelaskan peran broker, publish, subscribe, dan topic dalam MQTT.
Membandingkan protokol MQTT dengan HTTP.
Menggunakan Mosquitto sebagai broker MQTT.
Melakukan praktik sederhana komunikasi MQTT.

1. Pengenalan MQTT

MQTT (Message Queuing Telemetry Transport) adalah protokol komunikasi pengiriman pesan yang dibentuk dengan TCP/IP berdasarkan model messaging publish-subscribe dan dirancang khusus untuk machine to machine yang tidak memiliki alamat khusus. Publisher mengirim pesan, subscriber menerima pesan yang dibutuhkan, dan broker akan menyampaikan pesan yang diminta, dari pengirim ke penerima. Publisher dan subscriber adalah klien MQTT yang hanya berkomunikasi dengan broker MQTT. Contoh publisher dan subscriber adalah mikrokontroller, komputer, smartphone, dll.

2. Sejarah MQTT

MQTT dikembangkan pada tahun 1999 oleh Andy Stanford-Clark (IBM) dan Arlen Nipper (Arcom). Protokol ini awalnya digunakan untuk memantau jaringan pipa minyak. Sekarang, MQTT menjadi standar terbuka (OASIS) dan digunakan luas dalam berbagai aplikasi IoT.
Sejak Internet of Things menjadi populer, MQTT juga melonjak.

2008 - Broker MQTT open-source pertama, Mosquitto diciptakan.
2012 - Projek Eclipse Paho menyediakan library klien MQTT open-source untuk Java, C, JavaScript, dan Python dan dari sana daftar library klien MQTT telah bertambah.
Akhir 2014 - MQTT versi 3.1.1 menjadi standar OASIS dan membuka jalan untuk MQTT untuk menjadi standar ISO.
2017– MQTT banyak digunakan oleh perusahaan teknologi terkemuka seperti Amazon, Microsoft, IBM, dll.

3. Broker

Broker adalah server pusat yang menerima pesan dari publisher dan mendistribusikannya kepada subscriber. Broker memastikan pesan terkirim sesuai topic yang di-subscribe. Contoh broker populer: Mosquitto, HiveMQ, dan EMQX.

4. Publish

Publish merupakan cara suatu perangkat untuk mengirimkan datanya ke subscribers. Pengirim data tersebut dinamakan publisher. Biasanya pada publisher adalah sebuah device yang terhubung dengan sensor tertentu.
Contoh publisher adalah Arduino, ESP32, Raspberry Pi, Android, dll.

5. Subscribe

Subscribe merupakan cara suatu device untuk menerima berbagai macam data dari publisher melalui broker. Penerima data disebut subscriber. Subscriber dapat berupa aplikasi monitoring sensor dan sebagainya, subscriber ini yang nantinya akan meminta data dari publisher melalui broker.

6. Topic

Topic seperti halnya pengelompokan data disuatu kategori tertentu yang dibuat oleh user. Pada sistem kerja MQTT protokol ini, topic bersifat wajib untuk membedakan data satu dengan yang lainnya. Pada setiap transaksi data antara Publisher dan Subscriber harus memiliki suatu topic tertentu. Contoh penggunaan topic: “temperature”, “humidity“, dll.

7. Cara Kerja MQTT

Klien melakukan koneksi ke broker.
Publisher mengirim pesan ke sebuah topic.
Broker menerima pesan dan mendistribusikannya.
Subscriber yang berlangganan topic tersebut menerima pesan.

8. MQTT vs HTTP

Tabel Perbandingan MQTT dengan HTTP

Design Methodoloty

Aspek	MQTT	HTTP
Full Form	Message Queue Telemetry Transport	HyperText Transfer Protocol
Data Centric	Document centric
Architecture	Publish/Subscribe	Request/Response
Complexity	Simple	More Complex
Message Size	Small, with a compact binary header just 2 bytes in size	Larger, partly because status detail in text-based
Service Levels	3 quality of service settings	All messages get the same level of service
Data Distribution	1 to 0, 1 to 1, 1 to n	1 to 1 only
Data Security	Yes	No

9. Mosquitto

Mosquitto adalah broker MQTT open-source yang ringan dan populer, dikembangkan oleh Eclipse Foundation. Mendukung MQTT v3.1, 3.1.1, dan 5.0, serta bisa dijalankan di Linux, Windows, dan Raspberry Pi.

Website: https://mosquitto.org

Keamanan Pada Mosquitto

Mosquitto mendukung keamanan dengan mengenkripsi port yang digunakan dalam transmisi data. Beberapa port yang dapat digunakan yaitu:
• 1883 : MQTT, unencrypted, unauthenticated
• 1884 : MQTT, unencrypted, authenticated
• 8883 : MQTT, encrypted, unauthenticated
• 8884 : MQTT, encrypted, client certificate required
• 8885 : MQTT, encrypted, authenticated
• 8886 : MQTT, encrypted, unauthenticated
• 8887 : MQTT, encrypted, server certificate deliberately expired
• 8080 : MQTT over WebSockets, unencrypted, unauthenticated
• 8081 : MQTT over WebSockets, encrypted, unauthenticated
• 8090 : MQTT over WebSockets, unencrypted, authenticated
• 8091 : MQTT over WebSockets, encrypted, authenticated

10. Praktik MQTT dengan Mosquitto

1. Simulasi MQTT: Mengirim data dari ESP32 ke Mosquitto

Buat Diagram ESP32 pada Simulator Wokwi
Tambahkan code pada scetch.ino

#include <WiFi.h>
#include <PubSubClient.h>

// Update these with values suitable for your network.
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "test.mosquitto.org";

WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE	(50)
char msg[MSG_BUFFER_SIZE];
int value = 0;

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();

  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == '1') {
    digitalWrite(2, LOW);   // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is active low on the ESP-01)
  } else {
    digitalWrite(2, HIGH);  // Turn the LED off by making the voltage HIGH
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP8266Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected");
      // Once connected, publish an announcement...
      client.publish("/asaindo/mqtt", "Asaindo");
      // ... and resubscribe
      client.subscribe("/asaindo/mqtt");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  pinMode(2, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    ++value;
    snprintf (msg, MSG_BUFFER_SIZE, "Asaindo #%ld", value);
    Serial.print("Publish message: ");
    Serial.println(msg);
    client.publish("/asaindo/mqtt", msg);
  }
}

Tambahkan library PubSubClient pada Library Manager
Jalankan simulasi

Pada serial output dapat dilihat ESP32 mengirim data dan menerima data

2. Simulasi MQTT: Mengirim data dari ESP32 ke Mosquitto, kemudian ESP32 yang lain mengambil data dari Mosquitto.

PUBLISHER

Buat Diagram ESP32 sebagai publisher pada Simulator Wokwi
Tambahkan code pada scetch.ino

#include <WiFi.h>
#include <PubSubClient.h>

// Update these with values suitable for your network.
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "test.mosquitto.org";

WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE  (50)
char msg[MSG_BUFFER_SIZE];
int value = 0;

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();

  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == '1') {
    digitalWrite(2, LOW);   // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is active low on the ESP-01)
  } else {
    digitalWrite(2, HIGH);  // Turn the LED off by making the voltage HIGH
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP8266Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected");
      // Once connected, publish an announcement...
      client.publish("/asaindo/mqtt", "Asaindo");
      // ... and resubscribe
      client.subscribe("/asaindo/mqtt");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  pinMode(2, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {

  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    ++value;
    snprintf (msg, MSG_BUFFER_SIZE, "Asaindo #%ld", value);
    Serial.print("Publish message: ");
    Serial.println(msg);
    client.publish("/asaindo/mqtt", msg);
  }
}

Tambahkan library PubSubClient pada Library Manager
Jalankan simulasi

Pada serial output dapat dilihat ESP32 mengirim data dan menerima data

SUBSCRIBER

Buat Diagram ESP32 sebagai subscriber pada Simulator Wokwi
Tambahkan code pada scetch.ino

#include <WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "test.mosquitto.org";

WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE  (50)
char msg[MSG_BUFFER_SIZE];
int value = 0;

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == '1') {
    digitalWrite(2, HIGH);   // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is active low on the ESP-01)
  } else {
    digitalWrite(2, LOW);  // Turn the LED off by making the voltage HIGH
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP8266Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("Terkoneksi");
      // Once connected, publish an announcement...
      client.publish("/asaindo/mqtt", "Terkoneksi");
      // ... and resubscribe
      client.subscribe("/asaindo/mqtt");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  pinMode(2, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

Tambahkan library PubSubClient pada Library Manager
Jalankan simulasi

Pada serial output dapat dilihat ESP32 mengirim data dan menerima data

3. Simulasi MQTT: Pengiriman data ESP32 Mosquitto ke Smartphone.

Praktik pengiriman data dari ESP32 ke Mosquitto, kemudian smartohone mengambil data dari Mosquitto.

PUBLISHER

Buat Rangkaian ESP32 dan DHT22 sebagai publisher pada Simulator Wokwi

Tambahkan code pada scetch.ino

#include <WiFi.h>
#include <PubSubClient.h>
#include "DHTesp.h"

const int DHT_PIN = 15;
DHTesp dhtSensor;

const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "test.mosquitto.org";

WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE	(50)
float temp = 0;
float hum = 0;
int value = 0;

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == '1') {
    digitalWrite(2, LOW);   // Turn the LED on (Note that LOW is the voltage level
    // but actually the LED is on; this is because
    // it is active low on the ESP-01)
  } else {
    digitalWrite(2, HIGH);  // Turn the LED off by making the voltage HIGH
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = "ESP8266Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected");
      // Once connected, publish an announcement...
      client.publish("/asaindo", "Connected");
      // ... and resubscribe
      client.subscribe("/asaindo");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  pinMode(2, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    TempAndHumidity  data = dhtSensor.getTempAndHumidity();

    String temp = String(data.temperature, 2);
    Serial.print("Temperature: ");
    Serial.println(temp);
    client.publish("/asaindo/temp", temp.c_str());
    
    String hum = String(data.humidity, 1);
    Serial.print("Humidity: ");
    Serial.println(hum);
    client.publish("/asaindo/hum", hum.c_str());
  }
}

Tambahkan library PubSubClient, dan DHTesp pada Library Manager
Jalankan simulasi

Pada serial output dapat dilihat ESP32 mengirim data

SUBSCRIBER

Instal aplikasi MQTT Dashboard

Tambahkan Broker - Use Demo Credential (id bisa berbeda-beda)

Jalankan Broker, tap broker yang baru saja dibuat (Connected)

Tambahkan Subscriber

Lihat Messages

Daftar Pustaka

OASIS. (2019). MQTT Version 5.0. OASIS Standard.
Eclipse Mosquitto
HiveMQ - MQTT Essentials

Glosarium Istilah

MQTT: Protokol komunikasi publish-subscribe ringan untuk IoT.
Broker: Server yang mengatur distribusi pesan dari publisher ke subscriber.
Topic: Kanal komunikasi dalam MQTT yang menjadi jalur pesan.
Subscriber: Klien yang menerima pesan dari broker berdasarkan topic.

Beranda Mundur Maju