MQTT clients are applications or devices that use the MQTT protocol to send and receive messages. MQTT (Message Queuing Telemetry Transport) is a lightweight protocol developed for efficient communication between devices.
In this article, you will learn what MQTT is, what functionalities MQTT clients offer and how you can use them in your projects. Discover how MQTT clients collect and process real-time data and provide valuable insights for your decision-making.
MQTT and MQTT clients
MQTT is a lightweight message protocol that was developed for communication between devices via the Internet. It is particularly suitable for devices with limited computing power or for networks with low bandwidth. An MQTT system mainly consists of a broker and several clients. The broker is a server that receives and forwards messages. Clients are the devices or applications that send (publish) or receive (subscribe) messages. MQTT clients are often used in IoT (Internet of Things) applications. For example, sensors in a smart home can send their data to a central server, which then controls other devices, such as thermostats or lighting systems.
Functionalities of a MQTT client
An MQTT client must first connect to a broker in order to send or receive messages. This connection remains active as long as the client is active, which enables continuous communication. A client can register (subscribe) to certain message topics and only receive the messages that interest it. Similarly, a client can send (publish) messages to certain topics so that other interested clients can receive them.
MQTT offers three quality levels for message transmission:
- QoS 0: The message is sent a maximum of once and no acknowledgement is expected.
- QoS 1: The message is sent at least once and an acknowledgement is expected.
- QoS 2: The message is sent exactly once and a complex confirmation process is carried out to avoid duplicates.
Implementation and use of an MQTT client
There are many MQTT client libraries and software solutions that are suitable for different programming languages and use cases. Here are some popular MQTT clients:
This list shows a selection of MQTT clients that can be used in different environments and for different use cases. The OPC Router stands out as a user-friendly middleware solution that requires no programming knowledge and is particularly suitable for industrial applications.
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