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Blog has moved

From now on I will be posting on https://snorristurluson.github.io/

Most of my postings have code snippets in them and I've been using markdown, checking into a GitHub repo, then copying and pasting the contents. Using a static site generated with Jekyll just seems easier. Thanks, Blogger - I have moved on...

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Working with Xmpp in Python

Xmpp is an open standard for messaging and presence, used for instant messaging systems. It is also used for chat systems in several games, most notably League of Legends made by Riot Games. Xmpp is an xml based protocol. Normally you work with xml documents - with Xmpp you work with a stream of xml elements, or stanzas - see https://tools.ietf.org/html/rfc3920 for the full definitions of these concepts. This has some implications on how best to work with the xml. To experiment with Xmpp, let's start by installing a chat server based on Xmpp and start interacting with it. For my purposes I've chosen Prosody - it's nice and simple to install, especially on macOS with Homebrew : brew tap prosody/prosody brew install prosody Start the server with prosodyctl - you may need to edit the configuration file (/usr/local/etc/prosody/prosody.cfg.lua on the Mac), adding entries for prosody_user and pidfile. Once the server is up and running we can start poking at it

JumperBot

In a  previous blog  I described a simple echo bot, that echoes back anything you say to it. This time I will talk about a bot that generates traffic for the chat server, that can be used for load-testing both the chat server as well as any chat clients connected to it. I've dubbed it  JumperBot  - it jumps between chat rooms, saying a few random phrases in each room, then jumping to the next one. This bot builds on the same framework as the  EchoBot  - refer to the previous blog if you are interested in the details. The source lives on GitHub:  https://github.com/snorristurluson/xmpp-chatbot Configure the server In an  earlier blog  I described the setup of Prosody as the chat server to run against. Before we can connect bots to the server we have to make sure they can log in, either by creating accounts for them: prosodyctl register jumperbot_0 localhost jumperbot prosodyctl register jumperbot_1 localhost jumperbot ... or by  setting the authentication up  so that anyon

Simple JSON parsing in Erlang

I've been playing around with Erlang . It's an interesting programming language - it forces you to think somewhat differently about how to solve problems. It's all about pattern matching and recursion, so it takes bit getting used to before you can follow the flow in an Erlang program. Back in college I did some projects with Prolog  so some of the concepts in Erlang were vaguely familiar. Supposedly, Erlang's main strength is support for concurrency. I haven't gotten that far in my experiments but wanted to start somewhere with writing actual code. OTP - the Erlang standard library doesn't have support for JSON so I wanted to see if I could parse a simple JSON representation into a dictionary object. The code is available on Github:  https://github.com/snorristurluson/erl-simple-json This is still very much a work in progress, but the  parse_simple_json/1 now handles a string like {"ExpiresOn":"2017-09-28T15:19:13", "Scopes":