How does MQTT work? What is an MQTT client?

MQTT is a simple messaging agreement designed for constrained tools with low transmission capacity under the Azure IoT hub. So, it’s the perfect solution to exchange data between multiple IoT tools.

Devices publish messages on a specific matter.

Its main applications include sending messages to manage outputs, reading and publishing data from sensor nodes, and much more under MQTT.


Akenza uses low Iot solutions that help to expand IoT items/solutions by joining, supervising, and managing devices. It has multiple power plugs, and akenza facilitates simple data processing in the following applications.

How do MQTT works?

As we mentioned, the MQTT protocol enables resource-constraint IoT devices to issue or deliver information about some topics to a server that works as an MQTT message broker under the Azure IoT hub.

The broker’s function is to send that piece of information to only those clients previously subscribed to that matter under MQTT.

In simple words, we can describe this essential point as the publisher is responsible for generating and transmitting information to subscribers through a broker under MQTT. The primary function of a broker is to guarantee security by checking the authorization of subscribers and creators under the Azure IoT hub.

To explain the working of the MQTT protocol, we will divide the MQTT session into four stages: connection, authentication, communication, and termination.

  • First, a TCP/IP connection is initiated from the client to the broker using a standard or custom port defined by a broker operation under MQTT.
  • While establishing a connection, it’s essential to recognize whether the server has continued an old or new time.
  • The old-time continued if reused client identity is supplied to the broker under the Azure IoT hub.


As mentioned above, the MQTT protocol is resource-constrained, it is widely used in IoT devices, and SSL is only sometimes an alternative, so it is not desirable in some matters under the Azure IoT hub.

But in such matters, this authentication is delivered as clear content username and password, and the client it to the server by attaching it in connect packet sequence under MQTT.

Authentication and Termination

The client can perform publishing, subscribing, unsubscribing, and ping operations during the communication phase. The primary function of publishing is to send a binary block of data defined by the publisher under the Azure IoT hub.

The format of the content is application specific. A packet pair named subscribe is used for subscription service, and unsubscribing operation unsubscribe packet pair is used under MQTT.

The client can use the ping packet sequence to check its connection with the broker for ping operation under MQTT. One crucial point to remember is that there is no direct connection between the publisher and the subscriber under the Azure IoT hub.

Advantages of MQTT protocol:

  • Good choice for wireless networks
  • Distribute information reliably
  • Increase the scalability of the network
  • Reduce bandwidth consumption of the network
  • It is well suited for control and remote sensing
  • Lightweight overhead
  • Reduce updating rates to seconds
  • It uses permission-based security, making it more secure under the Azure IoT hub
  • Saves development time
  • Subscribe protocols can collect more data using less bandwidth than other polling protocols under MQTT.
  • Maximize the available bandwidth.



When we discuss a client, we almost always contemptible an MQTT client. Both publishers and subscribers are MQTT clients. The publisher and subscriber labels indicate whether the client is publishing messages or subscribed to receive notifications under the Azure IoT hub.

An MQTT client is any device that executes an MQTT library and links to an MQTT broker over the web under MQTT.

For instance, the MQTT client can be a small, resource-constrained tool that links over a wireless network and has a bare-minimum study under the Azure IoT hub.

The MQTT client can also be a classic computer managing a graphical MQTT client for testing objectives under MQTT.

How to select an MQTT client?

MQTT client gadgets are commonly used to initiate connections to MQTT brokers for subscription, message-sending, and receiving actions under the Azure IoT hub. A suitable MQTT client device should have the following characteristics.

  • Support for one-way and two-way SSL verification.
  • Support for MQTT 5 factors.
  • Maintain ease of use on a full-featured groundwork.
  • Support for multiple clients online at the same time under MQTT.
  • Cross-platform, available under different working systems under the Azure IoT hub.
  • Support MQTT over WebSocket.
  • Advanced features: Customized script, logging, payload format transmission, etc.

MQTT Explorer

MQTT Explorer is an extensive MQTT client that gives a structured outline of your MQTT topics and makes working with devices/services on your broker dead simple under MQTT.

MQTT Explorer can only create a single connection and cannot have multiple clients online simultaneously. It supports difference comparison and visual chart display of received payload messages under the Azure IoT hub. Similar to MQTT.


  • Visualize topics and dynamic research of the change of topic
  • Delete the retained topics
  • Search topics
  • Recursive delete topics
  • A different view of current and previously received messages under the Azure IoT hub
  • Publish topics
  • Draw digital topics
  • Retain the historic record of every topic
  • Dark/light topic