What is MQTT Protocol?

MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol widely used in IoT applications for real-time communication between devices. It operates on a publish-subscribe model, where clients connect to a central broker to either publish messages to specific topics or subscribe to receive messages from those topics. The protocol supports various Quality of Service (QoS) levels to ensure message delivery reliability, and it allows for retained messages so new subscribers can receive the last known state immediately. MQTT's architecture is characterized by its lightweight footprint, scalability, support for asynchronous communication, and secure transmission through TLS/SSL encryption, making it suitable for environments with limited resources and unreliable networks. Despite its advantages, MQTT faces limitations such as a restricted message size, lack of built-in security, and potential complexity in setup. It is supported by numerous programming languages and platforms, with cloud services like AWS IoT Core and Google Cloud IoT Core providing managed MQTT solutions. Over time, MQTT has evolved with several versions, including the widely used MQTT v3.1 and the more recent MQTT v5.0, which introduces enhanced features and error-handling capabilities.