The protocol MQTT (Messaging Queueing Telemetry Transport) is a messaging protocol designed for low-bandwidth, high-latency networks, making it well-suited for IoT devices that require frequent, small data transmissions such as smart meters, environmental sensors or wearable health devices.
Developed in the late 1990s by Andy-Stanford Clark of IBM and Arlen Nipper of Euortech, it was initially intended to be used in oil pipeline sensors and is now one of the most commonly used protocols in IoT systems.
How does MQTT work?
MQTT follows a publish/subscribe communication model, which sets it apart from the traditional request/response models found in protocols such as HTTP. Instead of devices communicating directly with each other, a central broker manages the flow of messages between clients, which can either publish data or subscribe to receive specific data topics. This model not only reduces the complexity of communication but also improves scalability and efficiency in environments with numerous devices.
At the heart of MQTT is its publish/subscribe architecture. This model enables devices to communicate indirectly via a broker, which acts as a mediator between publishers and subscribers.
The publisher is a device that sends messages on a specific topic to the broker. For example, a temperature sensor could publish temperature readings on a topic called, “home/temperature”.
The subscriber is a device that subscribes to a topic to receive relevant messages. For example, a smart thermostat could subscribe to the same topic to monitor temperature changes and adjust accordingly.
The broker is the central entity in the MQTT ecosystem. It receives messages from publishers and forwards them to subscribers that have registered interest in specific topics. Brokers are responsible for managing subscriptions and ensuring that messages reach the appropriate recipients.
This publish/subscribe architecture offers several advantages over direct communication. For instance, the devices do not need to know about each other’s existence; the broker handles all routing. This decouples the sender and receiver, making the system much more scalable.
Additionally, the broker can store messages for devices that are temporarily offline, ensuring that important updates are not lost. This feature is especially valuable in IoT systems, where network reliability can vary.
Other communication protocols
HTTP: HTTP is one of the most commonly used protocols for communication on the web. However, its request/response model is less suited for IoT, where devices may need continuous updates without initiating requests. MQTT, with its publish/subscribe model, is usually more efficient in such scenarios. HTTP’s verbosity also leads to higher power consumption and increased bandwidth usage, making it less ideal for low-power IoT devices.
CoAP (Constrained Application Protocol): CoAP is another protocol designed for resource-constrained environments, like IoT. While it offers a lightweight approach similar to MQTT, CoAP follows a request/response model rather than the publish/subscribe system of MQTT. CoAP is better suited to applications requiring direct device-to-device communication, whereas MQTT excels in scenarios where a broker-based system is advantageous.
Conclusion
MQTT has proven to be a crucial protocol in the world of IoT, offering a lightweight, efficient, and scalable solution for communication in constrained environments. Its publish/subscribe model, coupled with features like Quality of Service levels, retained messages, and low power consumption, makes it an ideal choice for a wide range of IoT applications.
There’s plenty of other editorial on our sister site, Electronic Specifier! Or you can always join in the conversation by commenting below or visiting our LinkedIn page.
