MQTT (Message Queuing Telemetry Transport) is an asynchronous and decoupled communication protocol that uses the publish / subscribe paradigm (like Twitter, for instance).
It is an asynchronous and decoupled communication paradigm. Subscribers (receivers) subscribe to topics and publishers (senders) publish messages on topics. The broker manages the topics: when a topic receives a message it is sent to all its subscribers. The topics allow a decoupling between publisher and subcriber.
Figure 1 - Example of communication between publishers and subscribers
Here you can find a list of free and paid public MQTT brokers
https://github.com/mqtt/mqtt.github.io/wiki/public_brokers
Public MQTT brokers list updated on November 2021
Name Broker address TCP port
EMQ X broker.emqx.io 1883
HiveMQ broker.hivemq.com 1883
Teserakt mqtt.teserakt.io 1883 (*)
Fluux mqtt.fluux.io 1883 (*)
(*) not working
Set the broker (server) domain name:
mqttserver=mqtt.teserakt.io
Set the port number:
mqttport=1883
Set the input topic:
mqttin=in
Set the output topic:
mqttout=out
Store the configuration:
] save
Connect to the Wi-Fi router first:
] wifi=1
ok
]
and wait for it to connect.
Wi-Fi connecting ...
]
Wi-Fi connected to 'Telekom-59086450' with IP: 192.168.1.252
]
After the connection there is an automatic connection to the NTP Server to update the calendar.
NTP connection to '0.de.pool.ntp.org' ...
NTP update of date and time: 19-04-2019 13:21:50
Then connect to the broker MQTT:
] mqtt=1
ok
]
and wait for it to connect.
MQTT connection to mqtt.teserakt.io:1883 ...
user: , client-ID: Smick-3448534573
subscribe to: in
publish on: out
]
MQTT connected to mqtt.teserakt.io:1883
]
< Conn
]
Sending the Conn message indicates that the connection has been made.