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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Installing and Starting Node-Red

Installing Node Red Node-Red is a node application and before you Install node red you will need to first install node. Here are the instructions: Installing Node on Windows Installing Node on Linux Using a Package Manager Then you can Install node red on Windows and Linux (including raspberry pi) using:

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Creating Flows- Node-Red Admin Basics

To administer node-red you will need to go the admin url. The admin url is the machine name or IP address followed by the port number. e.g  127.0.0.1:1880/ if you are running the browser on the same machines as node-red. localhost:1880/ – steve-laptop:1880/ when running node-red on a remote machine 192.168.1.154:1880/ I currently run node-red on a Raspberry Pi and use a second machine (windows 10) to create flows.   Using The Node Red Admin User Interface (UI) When you open the node-red admin screen for the first time you should start with an empty work space as shown in

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Using the Paho 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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How to Export and Import Flows-Node-Red

Node red makes it easy to save, share and move flows between computers using the export and import feature. Flows are exported as a JSON file and imported from a JSON file. You can export parts of a flow or the entire flow or even all flows.

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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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