Python Paho MQTT Client Send and Receive Integers and Floats

The Paho python MQTT client will accept a string payload and also a binary payload in the msg field. The receiver will need to know what type of data is in the payload. and decode it accordingly. When sending JSON data the data is a string and is passed directly into the publish  function see How to Send and Receive JSON Data Over MQTT with Python

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Python MQTT Bridge Project

Many networks will have a local MQTT broker (edge broker) which also connects to a cloud broker. The broker could be configured as an MQTT bridge and relay messages to the cloud broker.

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MQTT Client Message Queueing and Delivery

In this tutorial I want to talk about the pros and cons of queueing or buffering messages on an MQTT network. I want to start by discussing points of connection failure and the affects of failure  by using the reference diagram below:

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Publish and Subscribe Using the Python MQTT-SN Client

In this tutorial we will look at how you can subscribe and publish to topics using the Python MQTT-SN client. In addition we also look at topic registration as this is also part of the publish process The client is available to download at the bottom of this page.

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Using the Mosquitto_ctrl Tool

The Mosquitto_ctrl tool was introduced with mosquitto v2 and is used for dynamically making user and ACL changes on a mosquitto broker. To use it the target broker needs to have the dynamic security plugin enabled. The tool is effectively a modified mosquitto publish client and if you subscribe to the $CONTROL topic you can see the messages that it publishes (example shown below).

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Understanding and Using the Mosquitto Dynamic Security Plugin

The dynamic security plugin can be used instead of the password file and the ACL (Access Control list) . Mosquitto Username and Password Authentication -Configuration and Testing Mosquitto ACL -Configuring and Testing MQTT Topic Restrictions The plugin is available in mosquitto v2 but it is not enabled by default.

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Sparkplug Payloads and Messages

In a Sparkplug MQTT network there is no direct link between end nodes and the primary application (control node). All communication between nodes is via a central MQTT server. In this tutorial we will look at the message payloads and  how the various components establish a session with the MQTT broker and what they publish.

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