What is MQTT? And What are MQTT Broker and MQTT Client?

What is MQTT?

You need MQTT connection more than you think.

MQTT (Message Queuing Telemetry Transport) is a lightweight messaging protocol designed for constrained devices and low-bandwidth, high-latency or unreliable networks. It enables communication between remote devices, such as smartphones and web apps, sensors, and other systems.

Additionally, MQTT is successfully implemented in many industries, such as automotive, logistics, manufacturing, smart home, consumer products, transportation, etc

Principle of MQTT

In traditional network communication, the client and server communicate directly with each other. The client requests resources or data from the server, and then the server processes it and sends back a response.

The principle of MQTT (Message Queuing Telemetry Transport) is based on the publish/subscribe pattern. It uses the TCP/IP protocol for communication and achieves message publishing and subscribing through the connection between the client and the broker (proxy server). It follows a publish-subscribe model where clients can publish messages to topics or subscribe to topics to receive messages.

In MQTT, message publishers publish messages to specific topics, while subscribers receive messages by subscribing to topics. The broker is responsible for receiving messages from publishers and distributing them to subscribers who have subscribed to the respective topics.

MQTT Broker and MQTT Client

When it comes to establish the MQTT connection, there are two important parts in its connection. They are MQTT broker and MQTT client.

MQTT Broker

An MQTT Broker can be an application or a device. It is the critical component responsible for handing client requests, including establishing connections, disconnecting, subscribing, unsubscribing, and forwarding messages.

When a device or application needs to send a message, they publish it to a specific topic on the MQTT broker. Other devices or applications that have subscribed to the same topic will receive these messages. The MQTT broker ensures reliable delivery of messages, even unstable network conditions or when connections are lost.

MQTT brokers are widely used in industries such as power, renewable energy, smart cities, smart homes, smart metering, internet of vehicles, finance and payments, and telecommunications.

2. MQTT Client

An MQTT client is any device that runs an MQTT library and communicates with a server. If the client is sending messages, it acts a publisher; if it is receiving messages, it acts as a subscriber. Essentially, any device that uses MQTT for communication over a network can be referred to as an MQTT client device. For example, instant messaging applications using MQTT are clients, various sensors reporting data using MQTT are clients, and various MQTT testing tools are also clients.

Benefits

Simpler

MQTT is a messaging protocol that uses a publish/subscribe message pattern, providing one-to-many message distribution and decoupling of applications. Compared to other protocols, it is easier to develop with.

More Stable Network

It operates on the TCP/IP protocol, which provides a stable network connection.

Lightweight

MQTT has a small footprint and minimal overhead, minimizing protocol exchanges and reducing network traffic. It is suitable for low-bandwidth applications with small data payloads.

Wide Protocol Support

MQTT has broad support across various platforms and programming languages, making it easy to integrate into existing systems. There are numerous MQTT client libraries available, simplifying development for different devices and environments.

Openness

MQTT is an open protocol with source code, enabling its usage across different platforms.

In summary, MQTT is a simple, stable, open, and lightweight protocol with wide protocol support. It has broad applicability in areas such as information gathering, industrial control, smart homes, Internet of Things, small devices, and mobile applications, etc.