WebSocket Rack

Rack-based WebSocket server

Usage

Create sample rack config file, and inside build app basing on Rack::WebSocket::Application.

“uby require ‘rack/websocket’

class MyApp < Rack::WebSocket::Application end

map ‘/’ do run MyApp.new end

After that just run Rack config from Rack server:

“ash thin -R config.ru start

Done.

Configuration

Rack::WebSocket::Application make following methods available:

initialize

Called once after server is started. This is place for application configuration so each instance variables from here will be available in whole application.

Example:

“uby class MyApp < Rack::WebSocket::Application def initialize(options = {}) super @myvar = 4 end end

It is important to include ‘super’ in initialize function, so application will be properly configured.

Please notice that in some servers, when ‘initialize’ is called, EventMachine reactor is not running yet. If you would like to configure EventMachine-based software, then you need to put it inside ‘EM.next_tick’ block, so this function will be called in first cycle of reactor.

Example:

“uby class MyWebSocket < Rack::WebSocket::Application def initialize EM.next_tick { @redis = EM::Hiredis.connect } end end

on_open(env)

Called after client is connected. Rack env of client is passed as attribute.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_open(env) puts “Clien connected” end end

on_close(env)

Called after client is disconnected. Rack env of client is passed as attribute.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_close(env) puts “Clien disconnected” end end

on_message(env, msg)

Called after server receive message. Rack env of client is passed as attribute.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_message(env, msg) puts “Received message: ” + msg end end

on_error(env, error)

Called after server catch error. Variable passed is instance of Ruby Exception class.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_error(env, error) puts “Error occured: ” + error.message end end

send_data(data)

Sends data do client.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_open(env) send_data “Hello to you!” end end

close_websocket

Closes connection.

Example:

“uby class MyApp < Rack::WebSocket::Application def on_open(env) close_websocket if env[REQUEST_PATH] != ‘/websocket’ end end

Available variables:

@options

Options passed to app on initialize.

Example:

“uby

In config.ru

map ‘/’ do run MyApp.new :some => :variable end

In application instance

@options # => { :some => :variable }

FAQ

Which WebSocket drafts are supported:

Currently we support drafts -75 and -76 form old(hixie) numeration and all drafts from -00 to -13 from current(ietf-hybi) numeration. Please note that ietf-hybi-13 is currently proposed as final standard.

Which Rack servers are supported?

Currently we are supporting following servers:

  • Thin

How to enable debugging?

Just use :backend => { :debug => true } option when initializing your app.

How to enable wss/SSL support?

Thin v1.2.8 have –ssl option - just use that! :)

How to use function xxx?

Check Thin config - any option supported by Thin(like demonizing, SSL etc.) is supported by WebSocket-Rack.

About

Author: Bernard Potocki «[email protected]»

Released under MIT license.