iNS-316 User Manual
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4.9 MQTT
MQTT is a Client Server Publish/Subscribe messaging transport protocol. It is simple, lightweight, and
open, and is designed to be easy to implement. These characteristics make it ideal for use in many
situations, including constrained environments such as for communication in Machine-toMachine
(M2M) and Internet of Things (IoT) contexts where a small code footprint is required and/or network
bandwidth is at a premium.
MQTT is a protocol consisting of a Publish/Subscribe mechanism where the Client only needs to know
the IP address of the Broker. The Broker then acts as a central location to handle the sending and
receiving of all messages between a Publisher and a Subscriber. The Publisher is the entity that
publishes the topic and message, the Subscriber is the entity that receives the updated messages
from the Broker.
When the Publisher updates a message related to a specific topic, it is transmitted to the Broker,
which will then send the message to all Subscribers that have subscribed to that particular topic.
Neither the Publisher nor the Subscriber needs to know the status of the other.
The above is a schematic diagram of the system. Publishers are similar to various forms of the
publishing house and focus on updating commodities for different topics such as novels, newspapers,
magazines, etc. Subscribers are similar to consumers, who purchase, or subscribe to designated
commodities in a bookstore (Broker), which presents the latest information that has been designated
by the Subscriber.