What Is The Relationship Between Azure IoT Hub And MQTT?

Introduction: What exactly is MQTT?

MQTT stands for Message Queuing Telemetry Transport, which is the first thing you should know about it. It’s a communications standard created exclusively for Internet of Things (IoT) applications.

Andy Stanford-Clark and Arlen Nipper, who worked at IBM’s Cambridge software lab, created MQTT. Because it uses a publish-and-subscribe architecture, the protocol has become particularly popular with the Internet of Things because it makes it simple to link numerous devices or sensors. Under the OASIS standard, the MQTT protocol is based on TCP/IP.

What is Azure IoT Hub?

Azure IoT Hub is a cloud-service that serves as a central messaging hub for communication between IoT applications and their connected devices. You can safely and securely link millions of devices and their backend solutions. 

An IoT Hub may connect to almost any device, device-to-cloud telemetry, uploading files from devices, and request-reply techniques to manage your devices from the cloud are all supported communications patterns. Monitoring is also supported by IoT Hub, which allows you to keep track of device creation, device connections, and device failures.

How does MQTT Work?

The MQTT protocol uses a publish and subscribe mechanism, as previously mentioned. Messages can be transmitted in either direction between client and server using the publish and subscribe mechanism. This makes it possible for all the IoT devices to communicate with one another regardless of their geographical location. 

Even when networks are unstable or unresponsive, the MQTT protocol ensures that messages are delivered. It employs an acknowledgment system that informs both parties if data has been received appropriately.

The model of “publish and subscribe” of MQTT

In this paradigm, a publisher delivers messages to any other device that is interested in receiving them, which may be a single sensor or another form of internet-connected equipment such as a server. Subscribers, or devices that desire to receive data from the publisher, send back an acknowledgment of whether the data was received successfully.

The system’s publishers and subscribers do not have direct contact with one another. Instead, a broker manages the connection between the two entities by screening and delivering all incoming messages to the appropriate subscribers. These notions are represented in the MQTT protocol via the MQTT broker, MQTT clients, and MQTT topics, as shown below.

Broker for MQTT

The broker is the system’s nerve center. It is in charge of receiving all messages, filtering them, and forwarding them to subscribers, who in this case are MQTT clients. Millions of MQTT customers can possibly be handled by an MQTT broker.

Client for MQTT

A client is a device that can send and receive messages by interacting with the broker. A client can be a small IoT sensor that sends data at regular intervals or a smart computer program that displays IoT data in a graphical format.

A client can subscribe to a topic in the broker in order to get the messages associated with that subject. Similarly, a client can publish messages under a specific topic, which the broker will transmit to the subject’s subscribers.

MQTT as a message-transmission protocol

Topics are used to express interest in a certain sort of incoming communication and, conversely, to define where outbound messages should be published. A forward slash is used to separate several subject levels in an MQTT topic.

The Relationship Between Azure IoT Hub And MQTT

  • MQTT has been one of the most popular protocols for IoT applications in recent years. This is because of a number of things. To begin with, it is one of the simplest protocols now in use in the IoT. It’s a free and open standard that may be used on any type of hardware or software. Client libraries for all major programming languages are available, making it simple to create IoT applications utilizing MQTT.
  • The protocol enables very scalable projects to be implemented, potentially linking millions of IoT devices in a single system. MQTT’s bidirectional connectivity allows you to send messages to a large number of devices at once. MQTT has a variety of authentication and data security features, including TLS encryption.
  • Microsoft Azure Cloud is one of the most popular cloud environments available. Many ready-to-use services are available through the Azure Portal and may be quickly integrated. The final components are connected to construct cloud apps. The IoT Hub is one of these components, and it acts as the primary bidirectional connectivity for external data sources and IoT devices.
  • The OPC Router connects the IoT Hub and, as a result, the Azure Cloud, allowing data to be written to the Cloud as well as data to be obtained from the Cloud at the field level. With the OPC Router MQTT Client Plug-in, the IoT Hub may be connected. The OPC Router’s different plug-ins are used to implement data transmission at the field level or data procurement for the cloud.


The IoT Hub serves as a data entry point for the Microsoft Azure Portal. MQTT may be used to communicate with the IoT Hub. MQTT’s versatility allows it to accommodate a diverse range of use cases and IoT project topologies. Because the broker manages all connections, neither the publishers nor the subscribers of the system need to be aware of each other’s existence.