Simple Python MQTT Sensor Simulator

If you are trying to learn MQTT or are working on a MQTT prject then having access to real time data is very important. The aim of this project is to create a very simple two state binary sensor, that can be controlled externally using MQTT. The sensor could be used to simulate real world objects like lights, doors etc that have two states on or off, open or closed etc in IOT projects.

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Paho Python MQTT Client – Understanding Callbacks

Callbacks are functions that are called in response to an event. The events and callbacks for the Paho MQTT client are as follows: Event Connection acknowledged Triggers the on_connect callback Event Disconnection acknowledged Triggers the on_disconnect callback Event Subscription acknowledged Triggers the  on_subscribe callback Event Un-subscription acknowledged Triggers the  on_unsubscribe callback Event Publish acknowledged Triggers the on_publish callback Event Message Received Triggers the on_message callback Event Log information available Triggers the on_log callback

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Paho Python MQTT Client Objects

The main component of the Paho Python MQTT client library is the client class. The class provides all the necessary functions to connect to an MQTT broker, publish messages, subscribe to topics and receive messages. To use you will need to create a new client object from the client class. The client constructor takes 4 optional parameters. The default values are shown below:

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Python MQTT Client Connections– Working with Connections

The MQTT client uses a TCP/IP connection to the broker. Once the connection is established the client can send data to the broker, and the broker can send data to the client as required. You can consider a TCP/IP connection to be similar to a telephone connection. Once a telephone connection is established you can talk over it until one party hangs up.

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