Python MQTT Client The Loop and Callbacks Explained

When using the Paho Python MQTT client you will encounter the loop function .

In this video tutorial you will learn what the loop does and about the various loop methods .

You will learn how the loop trigger callbacks and what callbacks are and how they work.

You will also learn what to do if you have multiple client connections.

We take a detailed look at the on_connect callback and do some basic troubleshooting including how to make sense of any output you see from print statements with in the script as because of the asynchronous nature of callbacks they can occur anywhere in the output.

Finally we look at how we stop the loop from writing the script

Tutorial on Site
the loop
Understanding MQTT Clean Sessions
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MQTT Keep Alives Explained

[pareshkurdekar]

Your videos were extremely helpful.So, thank you for that.
I am trying to write a code so that two systems can publish and subscribe to each other.
Also after the on_message function, where does it return to?

[michaels]

Thanks for the videos steve. How can I wait to do an action on a flask server after I publish a message to a raspberry pi? Currently, the raspberry pi responds to the server with a confirmation the pump was turned on once the action was taken. The flask app on the server imports a script i wrote to handle callbacks...so I can view the message received from the pi. I am just confused as to how I can return the callback value to the flask app. Normally I have been writing the values to a text file and accessing them via the flask app. But I just use arbitary time pauses to wait until the message from the pi is written into the text file... is there a better way to do this?

[AlqGo]

Which thread call the callback functions? Is it the same thread that runs loop() in the background (if using loop_start()), or is it the main thread?

[AnushaYadav]

when we assign a callback function why we are not including the parameters when it is called?

[haarishk]

Steve how to send data or message from one system to another system using mqtt protocol

[francisgriffin]

I have had trouble taking in parts of Steve's videos. Whilst this is largely due to my inadequacies I don't think it is helped by the editing of the audio that seems to have removed the natural speech breaks and therefore one doesn't have time to understand the point being made before moving on to the next issue. I know that one can stop and rewind but that also has its drawbacks. Overall very good but a bit slower and a few more examples would be great.

[mohammedsameer]

how to make a client not to disconnect from the broker and keep listening to broker