What is Eclipse Mosquitto (MQTT)?
Eclipse Mosquitto
Eclipse Mosquitto is an open-source message broker that complies with the EPL/EDL license and supports MQTT versions 5.0, 3.1.1, and 3.1.
Mosquitto executable uses about 3MB of RAM while there are 1000 clients connected.
Mosquitto has a bridge that enables connections to other MQTT servers, including other Mosquitto instances.
What is MQTT?
The Internet of Things uses MQTT, an OASIS-recognized messaging standard. MQTT is an abbreviation for “MQ Telemetry Transport.”
By using a publish/subscribe approach, the MQTT protocol offers a simple way to conduct messages.
Basic concepts of MQTT
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Publish/Subscribe - A device may publish a message on a particular topic or subscribe to a specific topic to receive messages.
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Messages - The information we want to transfer between our devices is contained in messages.
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Topics - Using topics, we can indicate where to post a message or our interest in receiving incoming communications.
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Broker - The broker’s primary responsibility is to receive all communications, filter them, determine who is interested in them, and then send the message to all clients who have subscribed.
Syntax
The command for connecting to a host and subscribing to a topic using mosquitto_sub has the following syntax:
mosquitto_sub -h <hostname> -p <port> -u <username> -P <password> -t <topic>
hostname: An Internet host, or website, is recognized by a hostname.
port: In networking, a port is a numerical identifier assigned by software to a network protocol and used to receive or transmit data for a particular service.
username & password: A username or password that is used by someone who has access to a computer, network, or online service.
topic: Where to send a message or our interest from where to recieve a message.
Note: When deploying
mosquitto_sub, pass the-dparameter to view the subjects on which messages are published. For Example:
mosquitto_sub -h "thethings.example.com" -p "1883" -u "app1" -P "NNSXS.VEEBURF3KR77ZR.." -t "#" -d
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