MQTT connection

What is MQTT?

MQTT (Message Queuing Telemetry Transport) is an asynchronous and decoupled communication protocol that uses the publish / subscribe paradigm (like Twitter, for instance).

Publish/subscribe model

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

Public MQTT broker

Here you can find a list of free and paid public MQTT brokers

https://github.com/mqtt/mqtt.github.io/wiki/public_brokers



Here's how to configure your test MQTT broker

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 broker

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.