correct way to instantiate Paho Client in JavaScript for wss (secure websocket)
The Paho documentation is unfortunately quite fragmented at the moment, and some links on Eclipse’s website do not work. Here are some working links (as of 05/2019): https://www.eclipse.org/paho/clients/js/ https://www.eclipse.org/paho/files/jsdoc/index.html https://github.com/eclipse/paho.mqtt.javascript And here’s a fantastic website by Steve: http://www.steves-internet-guide.com/using-javascript-mqtt-client-websockets/ There is an important breaking change in the Paho namespace, where you will run into trouble using…
WeiterlesenUnderstanding Erlang & Lua / Luerl for VerneMQ MongoDB auth_on_register hook
My goal / TLDR My goal with this blog post is to explain how to set custom mountpoints for VerneMQ by modifying the shipped MongoDB auth Lua script (lua/auth/mongodb.lua). Setting a custom mountpoint is possible with VerneMQ not only by setting mountpoints manually for specific listeners (e.g. ports), but also programmatically during authorization in your…
Weiterlesenmongo_orm Exception: missing bson key: publish_acl (Exception)
When you extend your field definitions in the mongo_orm document classes, specifically with embedded documents, you might run into the following runtime (!) error: Exception: missing bson key: <name> (Exception) This is not an error in your code – your code is raising, because the database structure is not as it expects it to be!…
WeiterlesenIntroduction to the SNAP protocol
Introduction S.N.A.P. is a protocol for communication between several connected hosts. It provides: · addressing · flags · ack/nak request · error detection (different error detection methods available) It can be run over different media, including RS485. It is optimized for a small footprint (limited computing, memory resources), but scaleable depending upon your needs. Basically,…
WeiterlesenElektronik-Gehäuse & Platinenabmessungen Standards
Abmessungen Raspberry Pi Ein Raspberry Pi 3B+ hat, als Vergleich, die Abmessungen: 85 mm x 56 mm für die Basisplatine. (USB & LAN, sowie andere Stecker ragen teilweise über die Platine hinaus). Hutschiene / DIN-Schiene Hutschiene: TS35, U-förmiges Profil. Standarisierte Befestigungsschiene für Gehäuse, Racks, Schaltschränke, u.s.w. Sie wird vielfach in der Industrie eingesetzt. Einer der…
WeiterlesenPackaging Python projects for Debian / Raspbian with dh-virtualenv
This article aims to explain some things to developers which don’t use Python a lot, and might struggle with some of the concepts otherwise. I highly recommend the lecture of the following article as an introduction to the concepts discussed here: https://www.dabapps.com/blog/introduction-to-pip-and-virtualenv-python/ pypi.org pypi.org is an official repository of software for the Python programming language.…
Weiterlesenmongo_orm custom name for collection
mongo_orm will automatically determine the name for your collection by using the Module and Class name, and appending an “s”. In cases where you want to name your collection, you can simply do this: class PapiTest < Mongo::ORM::Document collection_name “Buster” field test : String end get “/” do pt = PapiTest.new pt.test = “I want…
WeiterlesenAvahi how to assign several .local names to same IP
In some situations you would like to access the same computer / IP using different .local names. This is possible using the Avahi daemon. The following is written for Ubuntu 18.04 Bionic Beaver. Install Avahi apt install avahi-daemon avahi-utils Avahi automatically adds your computer’s hostname to the .local Domain. For instance, my computer is called…
WeiterlesenCreating a Raspbian repository
If you want to host your own Raspbian repository, this article is for you. A Raspbian repository consists of a special directory structure on a webserver. The files, including the packages, are all static – therefore this repository could also simply be hosted on an Amazon S3 instance, for example. The sources.list entry in Raspbian…
WeiterlesenTEK-Berry RAL light grey color comparison to official Pi Zero W case
The official Pi Zero W case is white, whereas the default TEK-BERRY sold as white is in reality RAL light-grey – a bit darker than white. Here’s two pictures. When placed side by side you can see the difference, otherwise it is hard to tell that the case is not indeed 100 % white: The…
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