- MQTT (Message Queuing Telemetry Transport) is a messaging protocol used for communication in IoT (Internet of Things) systems.
- The protocol uses a publish/subscribe messaging model where a device can publish a message to a broker, and other devices can subscribe to messages on that broker.
- The broker receives messages from publishers and sends them to all subscribers that are interested in them.
- MQTT is designed to be lightweight and efficient, making it suitable for communication between devices with limited processing power, memory, and battery life.
- MQTT uses a Quality of Service (QoS) system to ensure reliable message delivery. The QoS system has three levels of reliability:
- QoS 0: “At most once” delivery. The message is sent to the broker without any acknowledgement, and the broker doesn’t attempt to redeliver the message if it is lost.
- QoS 1: “At least once” delivery. The message is sent to the broker, and the broker acknowledges the message to the publisher. If the acknowledgement is not received, the broker will attempt to redeliver the message.
- QoS 2: “Exactly once” delivery. The message is sent to the broker, and the broker acknowledges the message to the publisher. The broker and the subscriber exchange messages to ensure that the message is delivered exactly once.
- MQTT uses topics to group related messages, and devices can subscribe to specific topics to receive messages only on those topics.
- MQTT is widely used in IoT systems, and there are many open-source libraries and tools available for developers to use.
Overall, MQTT is a lightweight and efficient messaging protocol that is used in IoT systems. It uses a publish/subscribe messaging model, a QoS system to ensure reliable message delivery, and topics to group related messages.
