Public MQTT Brokers and Reserved Topics – Discussion Post

Preface This is a discussion post and these are currently my thoughts on this topic. I would be grateful for comments and feedback. Introduction MQTT is still in the early stages of deployment and currently is used only on private networks. However with the growth in the adoption of the MQTT protocol for information distribution the number of public brokers and topics will probably increase substantially just as happened with websites in the early days of the internet.

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Using the Node.js MQTT Client-Starting Guide

The node.js MQTT client is an open source client that can be used for publishing messages and subscribing to topics on an MQTT broker. It  can be installed using: npm install mqtt –save and npm install mqtt -g To install the command line tools Documentation for the client is available here

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Configuring the MQTT Publish and Subscribe Nodes in Node-Red

Node-Red provides both an MQTT subscribe (input) and publish (output) node. The configuration for these nodes are almost Identical as the main part of the configuration concerns the actual client connection. Because of this it is useful to think of the publish and subscribe nodes as consisting of two components as shown in the schematic below: Before we look a the actual configuration we will look at MQTT client connections in general.

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Logging MQTT Sensor Data

Most MQTT brokers don’t provide any mechanism for logging historical data for later analysis. However due to the publish/subscribe nature of MQTT is is easy to monitor, and log a data stream or streams using an MQTT client.

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Using The JavaScript MQTT Client With Websockets

Web browsers use the http protocol and modern ones can also use websockets. However web browsers don’t have MQTT support built in. To publish and subscribe to an MQTT broker with a browser you will need to use a JavaScript MQTT over websockets client. See the MQTT over websockets if you’re not familiar with MQTT over websockets. This client enables you to create web Apps that use the MQTT protocol for displaying and sending data. In this tutorial I will take you through a example script that publishes messages and subscribes to topics using MQTT and websockets.

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Creating an MQTT Broker With CloudMQTT

Cloud based brokers are likely to become very popular in the future for organisations they operate over a wide geographic area. In addition they provide a nice user interface making it very easy to setup your own broker instance and you don’t need to have to manage your own virtual server. CloudMQTT like Amazon,Azure etc provide a managed cloud based mosquitto broker. The plans on CloudMQTT are shared plans which means that several MQTT brokers run on the same hardware.

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MQTT Keep Alive Interval Explained With Examples

MQTT uses a TCP/IP connection. This connection is normally left open by the client so that is can send and receive data at any time. If no data flows over an open connection for a certain time period then the client will generate a PINGREQ and expect to receive a PINGRESP from the broker.

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Creating an IOT or MQTT Dashboard Using Thingsboard

Thingsboard is an open source IOT platform for data visualization. It is available for download and installation on your own hardware or as an online service for demonstration purposes. In this tutorial we will configure a simple Dashboard to display data from sensors using MQTT and Python.

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