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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Configure a Mosquitto Bridge With SSL Encryption
It is very likely that a bridged connection between two brokers will be encrypted. The Mosquitto broker (server) provides two methods of using SSL encryption on a bridged connection Certificate encryption PSK encryption In this tutorial we will be configuring a secure bridged connection using both methods. If you are new to certificates then you should read this tutorial on SSL encryption and certificates before continuing.
Continue readingGuide to IOT Networking and Messaging Protocols
The Internet of things (IOT) will utilize the existing networking infrastructure, technologies and protocols currently used in homes/offices and on the Internet, and will introduce many more. The purpose of this tutorial is to give you a quick overview of what networking and application protocols are likely to be used to build the IOT.
Continue readingQuick Guide to The Mosquitto.conf File With Examples
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Continue readingDNS Zones and Zone Files Explained
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Continue readingUsing The Mosquitto_pub and Mosquitto_sub MQTT Client Tools- Examples
The Mosquitto_pub and Mosquitto_sub client utilities comes with the Mosquitto package, and are excellent tools for conducting quick tests and troubleshooting.. In this tutorial we are going to be looking at some examples of using these tools for publishing and subscribing.
Continue readingMQTT Sensors and Network Traffic Observations
MQTT is primarily a M2M protocol. It was originally designed for send sensor data from a remote oil field. As the number of sensors increases the amount of network traffic generated by sensors will increase dramatically and depending on the transport it could prove expensive. It will be important to understand this sensor traffic and how it can be reduced.
Continue readingHost Name Resolution Methods Explained
On computer and home networks when you type an Internet address into a web browser the web browser needs to convert that web address into an IP address. To do that it uses the the name resolution processes provided by the host machine. There are several ways that the host machine can resolve a domain name. The main ones are:
Continue readingDNS Lookups Explained
In this tutorial we will examine what happens when you use DNS to lookup or resolve a domain name to an IP address. We look at how DNS lookups work, and the exact process involved when looking up a domain name. We follow the client DNS query as it is processed by the various DNS servers in the response chain. Before we start it might be useful to compare DNS name resolution with a standard question and answer that takes place in everyday life.
Continue readingPaho Python MQTT Client-Understanding The Loop
When writing code using the Paho Python client you would have had to use the loop() function . In this tutorial we will look at what it does, and why it is necessary. When new messages arrive at the Python MQTT client they are placed in a receive buffer. The messages sit in this receive buffer waiting to be read by the client program.
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