npm i

subscriber1-666.js will receive messages for car/bmw/c-wa666/#
subscriber1-999.js will receive messages for car/bmw/c-wa666/#
subscriber1-all.js will receive messages for car/#

You will get examples how MQTT basically works and how Last will testament is working

1. Start all 3 subscriber1 666, 999, all
2. Execute 3.1.1/publisher1.js to send a message to different car topics
3. Execute 3.1.1/publisher2-lwt.js to see Last will messages example

You will get an example, how QoS 2 is working

1. Start subscriber3-qos.js and subscriber3-qos2.js
2. Execute 3.1.1/publisher3-qos0.js, see how message is arrived
3. Stop subscriber3-qos0.js and execute 3.1.1/publisher3-qos0.js again
4. Start subscriber3-qos0.js again and see if missed massage come in?
5. Stop subscriber3-qos2.js and execute 3.1.1/publisher3-qos2.js again
6. Start subscriber3-qos2.js again and see if missed massage come in?

You will get an example, how Retain messages are working

1. Start all 3 subscriber1 666, 999, all
2. Run 3.1.1/publisher4-retain.js and see how, message arrived
3. Stop subscriber1-999.js and after 5 seconds start again. See how last message was deliverd

This example demonstrate, how shared topics are working, which is a MQTT 5 function.

1. Start subscriber6-shared1.js multiple times. (At least two times to understand the function)
2. Start 5/publisher5-shared.js and see, how messages are distributed over subscriber

Do whatever you want with the code from this repository.