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technology/internet/MQTT.md

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+---
+obj: concept
+wiki: https://en.wikipedia.org/wiki/MQTT
+website: https://mqtt.org/
+---
+
+# MQTT
+MQTT is an OASIS standard messaging protocol for the Internet of Things (IoT). It is designed as an extremely lightweight publish/subscribe messaging transport that is ideal for connecting remote devices with a small code footprint and minimal network bandwidth. MQTT today is used in a wide variety of industries, such as automotive, manufacturing, telecommunications, oil and gas, etc.
+
+## Concepts
+### 1. **Publisher-Subscriber Model:**
+MQTT follows a publish-subscribe communication model, where clients (publishers) send messages to topics, and other clients (subscribers) receive messages from those topics.
+### 2. **Broker:**
+The MQTT broker is a server that receives published messages from clients and delivers them to the appropriate subscribers.
+### 3. **Topics:**
+Topics act as channels or categories to which messages are published. Subscribers express interest in specific topics to receive relevant messages.
+
+## MQTT Components
+### 1. **Publisher:**
+- A client that sends messages to a specific topic.
+### 2. **Subscriber:**
+- A client that expresses interest in a specific topic and receives messages published to that topic.
+### 3. **Broker:**
+- The server that handles message routing between publishers and subscribers.
+
+## Topics and Subscriptions
+Each message is inside a topic allowing for organizing them.
+### 1. **Topics:**
+- Hierarchical and structured, topics enable flexible message routing.
+### 2. **Wildcards:**
+- MQTT supports wildcards (`+` and `#`) for subscribing to multiple topics.
+
+## Real-world Use Case
+### 1. **IoT (Internet of Things):**
+- MQTT is widely used in IoT scenarios for efficient communication between devices.
+### 2. **Home Automation:**
+- Smart homes leverage MQTT for controlling and monitoring devices. For example zigbee2mqtt with [Home Assistant](../applications/web/Home%20Assistant.md).
+### 3. **Messaging in Remote Locations:**
+- Suitable for scenarios with low bandwidth, high latency, or unreliable connections.
+
+## Docker Compose
+To use MQTT with mosquitto as a broker:
+```yaml
+version: "3"
+  mqtt:
+    image: eclipse-mosquitto:2.0
+    restart: unless-stopped
+    volumes:
+      - "./mosquitto:/mosquitto"
+    ports:
+      - "1883:1883"
+```