volt-sockjs

h1. About

Disclaimer: This library is still work in progress.

SockJS is WebSocket emulation library. It means that you use the WebSocket API, only instead of @WebSocket@ class you instantiate @SockJS@ class. I highly recommend to read "SockJS: WebSocket emulation":http://www.rabbitmq.com/blog/2011/09/13/sockjs-websocket-emulation on the RabbitMQ blog for more info.

h2. Prerequisites

Even though this library uses Rack interface, Thin is required as "it supports asynchronous callback":http://macournoyer.com/blog/2009/06/04/pusher-and-async-with-thin. For Websockets, we use "faye-websocket":http://blog.jcoglan.com/2011/11/28/announcing-faye-websocket-a-standards-compliant-websocket-library gem.

h2. The Client-Side Part

For the client-side part you have to use JS library "sockjs-client":http://sockjs.github.com/sockjs-client which provides WebSocket-like API. Here's an example:

h2. The Server-Side Part

Now in order to have someone to talk to, we need to run a server. That's exactly what is sockjs-ruby good for:

#!/usr/bin/env ruby
# encoding: utf-8

require "rack"
require "rack/sockjs"
require "eventmachine"

# Your custom app.
class MyHelloWorld
  def call(env)
    body = "This is the app, not SockJS."
    headers = {
      "Content-Type" => "text/plain; charset=UTF-8",
      "Content-Length" => body.bytesize.to_s
    }

    [200, headers, [body]]
  end
end


app = Rack::Builder.new do
  # Run one SockJS app on /echo.
  use SockJS, "/echo" do |connection|
    connection.subscribe do |session, message|
      session.send(message)
    end
  end

  # ... and the other one on /close.
  use SockJS, "/close" do |connection|
    connection.session_open do |session|
      session.close(3000, "Go away!")
    end
  end

  # This app will run on other URLs than /echo and /close,
  # as these has already been assigned to SockJS.
  run MyHelloWorld.new
end


EM.run do
  thin = Rack::Handler.get("thin")
  thin.run(app.to_app, Port: 8081)
end

For more complex example check "examples/sockjs_apps_for_sockjs_protocol_tests.rb":https://github.com/sockjs/sockjs-ruby/blob/master/examples/sockjs_apps_for_sockjs_protocol_tests.rb

h2. SockJS Family

• "SockJS-client":https://github.com/sockjs/sockjs-client JavaScript client library.
• "SockJS-node":https://github.com/sockjs/sockjs-node Node.js server.
• "SockJS-ruby":https://github.com/sockjs/sockjs-ruby Ruby server.
• "SockJS-protocol":https://github.com/sockjs/sockjs-protocol protocol tests and documentation.
• "SockJS-protocol spec":http://sockjs.github.com/sockjs-protocol/sockjs-protocol-0.2.1.html

h1. Development

Get "sockjs-protocol":https://github.com/sockjs/sockjs-protocol (installation information are in its README) and run @rake protocol_test@. Now you can run the tests against it, for instance:

# Run all the tests.
./venv/bin/python sockjs-protocol-0.2.1.py

# Run all the tests defined in XhrStreaming.
./venv/bin/python sockjs-protocol-0.2.1.py XhrStreaming

# Run only XhrStreaming.test_transport test.
./venv/bin/python sockjs-protocol-0.2.1.py XhrStreaming.test_transport

h1. Links

• "SockJS: WebSocket emulation":http://www.rabbitmq.com/blog/2011/09/13/sockjs-websocket-emulation
• "SockJS: web messaging ain't easy":http://www.rabbitmq.com/blog/2011/08/22/sockjs-web-messaging-aint-easy
• "PubSubHuddle Realtime Web talk":http://www.rabbitmq.com/blog/2011/09/26/pubsubhuddle-realtime-web-talk