What is MQTT Protocol? (2020) | Learn Technology in 5 Minutes
11.9 هزار بار بازدید -
5 سال پیش
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Hello and welcome to another
Hello and welcome to another episode of “Learn Technology in 5 Minutes” from MAKERDEMY.
In this episode, we will learn about the MQTT protocol and why it is used in a number of IoT applications.
The MQTT protocol was originally developed by IBM and was proprietary. It was developed to solve the problem of connecting the sensors in the oil and gas industry with remote servers via satellite in a cost-effective manner. However, it is now an open protocol overseen by OASIS.
The MQTT is an application layer protocol like HTTP. However, there are significant differences between HTTP and MQTT on account of which the MQTT is preferred over HTTP in certain IoT applications.
To start with, the HTTP is a document-centric request-response protocol for client-server computing. The HTTP is the foundation of the world wide web, however, it is not specifically designed for machine to machine communication.
The MQTT, on the other hand, is a machine to machine, data-centric, a lightweight protocol designed to operate in resource-constrained environments. A lot of IoT projects require the devices to operate under a variety of resource constraints like limited processing capability, unattended network operation, highly unreliable networks, energy constraints and so on. In such constrained environments, the MQTT is much preferred over HTTP.
Unlike the direct client-server interaction in HTTP, the MQTT operates under a publish/subscribe paradigm with an MQTT broker in between. Clients can publish topics to the MQTT broker or subscribe to topics. The same client can publish topics X and Y and subscribe to a topic Z published by another MQTT client.
MQTT also allows persistent connection between the MQTT client and the broker and different quality of service levels, which makes it ideal for a variety of constrained environments, as it is more energy-efficient and faster than HTTP under such conditions.
Now, for some terminology. All devices that connect to an MQTT broker are MQTT clients. MQTT clients range from computers to your mobile phone to tiny constrained sensor devices. The MQTT broker is an MQTT server that transfers data between the different MQTT clients connected to it. When a client wants to send data to the broker, it “publishes” this data or topic. When an MQTT client wants to receive this data published by another MQTT client, it subscribes to this topic and the MQTT broker will then transmit this topic to the broker. This way, unlike the HTTP, the MQTT clients need not know each other’s IP address or the port numbers. All they need to do is to connect to the same MQTT broker. A single MQTT broker can handle a large number of MQTT clients and this number varies from broker to broker.
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5 سال پیش
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