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Showing posts from September, 2017

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":"myS…

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 to get a feel for h…