I am a software architect at CCP Games. Work on the launcher, Wine support, graphics engine and other random stuff for EVE Online, usually low level. This blog details some interesting things I run into at work, as well as new things I'm trying out in my spare time. Lately I've been picking up new programming languages - Erlang/Elixir, Go, Swift whereas most of my work in the past is in C++ and Python.
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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:
We also need to enable multi-room chat - do this by adding this to the Prosody configuration file (near the bottom of the file, in the Components section):
Component "conference.localhost" "muc"
The Jumperbot is similar to the EchoBot, but rather than handling incoming messages we set up an asyncio task as this bot is proactive where the echo bot was reactive. The task is created when the connection is made:
n = random.randint(5, 10)
for i inrange(n):
await asyncio.sleep(random.random() *10.0+5.0)
This implements the bot behavior as described above - joins a random room, says a few random phrases, then repeats the process in the next room. The asyncio.sleep command is very important - this allows other tasks to run concurrently with this loop.
Running a single JumperBot doesn't really generate much traffic and rather than running multiple processes, let's make use of asyncio and create multiple bots as tasks. For that, we set up a BotManager to create and monitor bots:
Each bot is a protocol instance associated with its connection and gets a callback, data_received whenever something is received from the server. The bot also runs its own task for initiating its chattiness, as described above.
The bots do their chatter in rooms named bot_room_0 through bot_room_9. Connect to the server with Swift (or your favorite chat client) and join one or more of those rooms to listen in. You can also run the jumperbot with a --verbose flag to see all the XMPP traffic in the log.
Learning new things is important for every developer. I've mentioned this before, and in the spirit of doing just that, I've started a somewhat ambitious project. I want to do a large-scale simulation, using Elixir and Go , coupled with a physics simulation in C++. I've never done anything in Elixir before, and only played a little bit with Go, but I figure, how hard can it be ? Exsim I've dubbed this project exsim - it's a simulation done in Elixir. Someday I'll think about a more catchy name - for now I'm just focusing on the technical bits. Here's an overview of the system as I see it today: exsim sits at the heart of it - this is the main server, implemented in Elixir. exsim-physics is the physics simulation. It is implemented in C++, using the Bullet physics library. exsim-physics-viewer is a simple viewer for the state of the physics simulation, written in Go. exsim-bot is a bot for testing exsim, written in Go.
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
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...