MQTT: Class wrapping MQTT mosquitto

A C++11 tiny wrapper class for a MQTT client based on the mosquitto implementation. You will need small code to make your application running with a MQTT client.

• See https://github.com/eclipse/mosquitto
• See https://www.howtoforge.com/how-to-install-mosquitto-mqtt-message-broker-on-debian-11/

Hello World example

• In a first Linux console, a subscriber will echo messages from our application. Type:

mosquitto_sub -h localhost -t "Example/Output"

• In a second Linux console, compile and launch our application. Type:

cd example
g++ --std=c++11 -Wall -Wextra -I../include ../src/MQTT.cpp Example.cpp -o example `pkg-config --cflags --libs libmosquitto`
./example

You will see (may be different from your case):

Connected to MQTT broker with error code 0
Message 1 subscribed. Granted QOS: 0

• In a third Linux console, a publisher will send messages to our application. Type:

mosquitto_pub -h localhost -t "Example/Input" -m "Hello"

You will see:

• In the first console:

Hello

• In the second console:

Received message 0: "Hello" from topic: "Example/Input" size: 5 qos: 0
Message 2 published

In this example, once a message has been received the application is closing.

Your C++ asynchronous MQTT client is functional :)