There are many protocols for exchanging information, from the widespread HTTP to the rarely seen PeSIT. Despite this, a separate protocol has been developed for the Internet of Things – MQTT. Let’s figure out where and how it is used.
The Scheme Of Work And Features Of The MQTT Protocol
MQTT is a specialized protocol for publishing small datasets on the Internet of Things. Its main area of application is the delivery of small messages, such as sensor readings.
Messages in MQTT are passed between three participants – publishers, broker and subscribers:
- Publishers are the senders of messages, such as sensors installed in thermometers and other IoT devices.
- Broker (MQTT broker) – The central hub of MQTT, which is responsible for communication between publishers and subscribers. The broker receives data from publishers, processes it, transfers it to subscribers, and controls delivery. Usually, the server software (MQTT Server) or the controller acts as a broker.
- Subscribers are the ultimate recipients of sensor data, such as an analytics system deployed in the cloud.
IoT devices (sensors) can be both publishers and subscribers. They need a subscription to receive telecontrol commands, update device configurations, and firmware versions. In this case, the system software sends the message through the broker, and the IoT device receives it.
The MQTT protocol has several features; let’s look at the main ones:
- MQTT is a binary protocol. When transferring data in a slow and unstable connection, you need to save every bit. Therefore, the data is sent as compactly as possible.
- MQTT does not have built-in mechanisms to protect data in transit, but SSL has been successfully used to get around this limitation.
- MQTT uses TCP / IP for connection and data transfer – this again saves bytes.
- The protocol is equipped with the LWT (last will) function. It notifies all parties of a network outage – an essential feature if the connection is unstable.
MQTT is well suited for IoT, as it is adapted to the characteristics of devices and communication channels. This protocol minimizes the computing power of intelligent devices and correctly delivers messages to the central node in an unstable connection.
Features Of Message Delivery
The data has a different value and delivery priority, so the Quality of Service – QoS flags are provided in MQTT:
- QoS 0 – the message is delivered no more than once. If delivery is interrupted, then the message may be lost – there will be no retry attempts.
- QoS 1 – the message is delivered at least once, and the recipient confirms delivery. In this case, the news may be duplicated.
- QoS 2 – The message is delivered only once, despite the problems and interference. Due to a failure, the delivery may be delayed, but the message will still reach the addressee, for example, after the connection is restored.
Application Of The MQTT Protocol: Monitoring Equipment, Environments And Sending Important Data
Let’s see where the MQTT protocol is most often used:
Equipment Monitoring Systems
In large factories, intelligent sensors are installed on machine tools, transformers, cranes and forklifts. They monitor the operation of industrial devices and transmit data to a central analytical system. This allows companies to monitor equipment performance in real-time, predict wear and tear, and assess plant performance.
Environmental And Structural Monitoring Systems
MQTT is used to analyze climate performance, seismic activity and building resilience. This allows predicting natural disasters and cataclysms, preventing the destruction of buildings.
Highly Reliable Systems For Working With Important Data
Although initially created as the MQTT protocol for the Internet of Things, it is used to bill mobile operators and providers. They need to transmit information about the movement of money in customer accounts without losing it.
What You Need To Know About The MQTT Protocol
- MQTT is a protocol invented for IoT, where publishers transmit data to a subscriber through a broker (MQTT server). Publishers and subscribers are also referred to as MQTT Clients.
- The protocol loads the computing power of smart devices to a minimum and works in poor communication conditions.
- QoS flags are provided in the MQTT settings; the priority of message delivery depends on them.
- The protocol is used in monitoring systems for equipment, environments and structures, and strategies for working with essential data.
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