MQTT (Message Queuing Telemetry Transport) is a commonly used transmission protocol for the Internet of Things based on publishing/subscribing. Released by the developer IBM in 1999, it is lightweight, simple, open and easy to implement. These characteristics make the MQTT protocol applicable to a wide range of applications. In a complex and limited application environment, as an instant messaging protocol with low bandwidth occupation, it has a wide range of applications in the Internet of Things, industrial equipment, mobile communications, etc., such as M2M machine-to-machine communication and IoT things networking. The MQTT protocol has been widely used in the Internet of Things through the data collection and communication capabilities of sensors, medical equipment, smart home and automation equipment.
What feature most of MQTT is to provide real-time and reliable message services for remotely connected devices with very little code and limited bandwidth. In addition, the MQTT protocol has the following characteristics:
- Use the message publishing and subscription mode to solve the coupling relationship with the application program;
- Small transmission, low overhead (fixed-length header is 2 bytes), minimize the protocol Exchange to save traffic consumption;
- Use Last Will and Testrament features to notify relevant parties of the mechanism of abnormal client interruption;
- Allow users to dynamically create topics, which is convenient for operation and maintenance at zero cost;
- Realize large bandwidth, low latency, and high stability 6. No restrictions on the type and format of transmitted data, ensuring data flexibility;