What is MQTT

Introduction

MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol that is designed for use in constrained environments such as low-power, low-bandwidth devices and unreliable networks. It is used for machine-to-machine (M2M) communication and IoT (Internet of Things) applications.

MQTT operates using a publish/subscribe model. This means that devices can publish messages to a specific topic, and other devices can subscribe to that topic and receive the messages. MQTT messages are identified by a topic string, which is used to route messages to the appropriate subscribers.

MQTT uses a client-server architecture, with a broker acting as the intermediary between publishers and subscribers. The broker receives messages from publishers and forwards them to all subscribers that have subscribed to the corresponding topic.

MQTT messages are small and efficient, which makes them ideal for use in low-power, low-bandwidth environments. The protocol supports three levels of Quality of Service (QoS) to provide different levels of reliability:

  • QoS 0: At most once delivery. The message is delivered once, but it may not be received by the subscriber.
  • QoS 1: At least once delivery. The message is guaranteed to be delivered at least once, but it may be delivered multiple times.
  • QoS 2: Exactly once delivery. The message is guaranteed to be delivered exactly once, but it may take longer to deliver than messages with lower QoS levels.

MQTT also supports the use of retained messages, which are messages that are saved by the broker and sent to new subscribers when they first connect. This is useful for providing the current state of a device or system to new subscribers.

In summary, MQTT is a lightweight messaging protocol designed for use in constrained environments. It uses a publish/subscribe model and a client-server architecture, with messages identified by topic strings. The protocol supports three levels of Quality of Service to provide different levels of reliability, and it also supports the use of retained messages.

 

Uses of MQTT

MQTT is a widely used protocol in the IoT (Internet of Things) and M2M (Machine-to-Machine) communication domains, where devices and systems are often constrained in terms of power, bandwidth, and network reliability. Here are some examples of where MQTT can be used:

  1. Smart Home: In a smart home, various sensors and devices such as temperature sensors, lighting systems, security systems, and smart appliances can use MQTT to communicate with each other and with the cloud.
  2. Industrial Automation: MQTT can be used for monitoring and controlling various machines and systems in an industrial setting. For example, temperature sensors, pressure sensors, and other types of sensors can use MQTT to send data to a central server for analysis and control.
  3. Healthcare: MQTT can be used in healthcare settings for monitoring patients, tracking medical equipment, and for real-time communication between healthcare professionals.
  4. Transportation: MQTT can be used for vehicle-to-vehicle communication and for monitoring and control of various systems in transportation such as traffic lights and public transportation systems.
  5. Agriculture: MQTT can be used for monitoring and control of various systems in agriculture, such as irrigation systems, crop monitoring, and livestock management.