Understanding IP Multicasting

What is IP Multicasting? -IP multicasting allows a host to send a single packet to thousands of hosts across a routed network i.e. The Internet. It is used mainly for audio (radio) and video distribution. In Networking a packet can be sent to: A single host –Unicast = (TCP and UDP) All hosts -Broadcast – (UDP only) A group of hosts – Multicast -(UDP only)

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Checking Active MQTT Client Connections

This tutorial is in response to a question I received on the client connections tutorial page: I’ve been struggling to find a real client connection status tool, dashboard or anything which will show a list of my clients and their connection status. Clearly the broker via the low-level protocol mechanics maintain an MQTT keepalive table for each client — that’s how Last Will and Testament (LWT) is triggered internally by the broker. However how does one display such table? The problem is that you have no way of accessing the connections table on the broker so the only way is to

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How to Install The Mosquitto MQTT Broker on Linux

In this tutorial we will look at how you install and run the mosquitto MQTT broker on a Linux server running for example Raspberry Pi or Ubuntu. Here are the steps I used on Ubuntu. sudo apt-add-repository ppa:mosquitto-dev/mosquitto-ppa sudo apt-get update sudo apt-get install mosquitto sudo apt-get install mosquitto-clients sudo apt clean For Raspberry Pi the instructions are taken from  here: wget http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key sudo apt-key add mosquitto-repo.gpg.key Then make the repository available : cd /etc/apt/sources.list.d/ Then , depending on which version of debian you are using: sudo wget http://repo.mosquitto.org/debian/mosquitto-jessie.list sudo wget http://repo.mosquitto.org/debian/mosquitto-stretch.list sudo wget http://repo.mosquitto.org/debian/mosquitto-buster.list Then update apt information: sudo

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MQTT Retained Messages Tool

This MQTT testing tool is a simple Python script that will list topics that have a retained message and optionally deletes the retained message. The script can be use from the command prompt by supplying options.

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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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