# faye-websocket * Travis CI build: [![Build status](https://secure.travis-ci.org/faye/faye-websocket-ruby.png)](http://travis-ci.org/faye/faye-websocket-ruby) * Autobahn tests: [server](http://faye.jcoglan.com/autobahn/servers/), [client](http://faye.jcoglan.com/autobahn/clients/) This is a general-purpose WebSocket implementation extracted from the [Faye](http://faye.jcoglan.com) project. It provides classes for easily building WebSocket servers and clients in Ruby. It does not provide a server itself, but rather makes it easy to handle WebSocket connections within an existing [Rack](http://rack.rubyforge.org/) application. It does not provide any abstraction other than the standard [WebSocket API](http://dev.w3.org/html5/websockets/). It also provides an abstraction for handling [EventSource](http://dev.w3.org/html5/eventsource/) connections, which are one-way connections that allow the server to push data to the client. They are based on streaming HTTP responses and can be easier to access via proxies than WebSockets. The following web servers are supported. Other servers that implement the `rack.hjiack` API should also work. * [Goliath](http://postrank-labs.github.com/goliath/) * [Puma](http://puma.io/) * [Rainbows](http://rainbows.rubyforge.org/) * [Thin](http://code.macournoyer.com/thin/) ## Installation ``` $ gem install faye-websocket ``` ## Handling WebSocket connections in Rack You can handle WebSockets on the server side by listening for requests using the `Faye::WebSocket.websocket?` method, and creating a new socket for the request. This socket object exposes the usual WebSocket methods for receiving and sending messages. For example this is how you'd implement an echo server: ```ruby # app.rb require 'faye/websocket' App = lambda do |env| if Faye::WebSocket.websocket?(env) ws = Faye::WebSocket.new(env) ws.on :message do |event| ws.send(event.data) end ws.on :close do |event| p [:close, event.code, event.reason] ws = nil end # Return async Rack response ws.rack_response else # Normal HTTP request [200, {'Content-Type' => 'text/plain'}, ['Hello']] end end ``` Note that under certain circumstances (notably a draft-76 client connecting through an HTTP proxy), the WebSocket handshake will not be complete after you call `Faye::WebSocket.new` because the server will not have received the entire handshake from the client yet. In this case, calls to `ws.send` will buffer the message in memory until the handshake is complete, at which point any buffered messages will be sent to the client. If you need to detect when the WebSocket handshake is complete, you can use the `onopen` event. If the connection's protocol version supports it, you can call `ws.ping()` to send a ping message and wait for the client's response. This method takes a message string, and an optional callback that fires when a matching pong message is received. It returns `true` iff a ping message was sent. If the client does not support ping/pong, this method sends no data and returns `false`. ```ruby ws.ping 'Mic check, one, two' do # fires when pong is received end ``` ## Using the WebSocket client The client supports both the plain-text `ws` protocol and the encrypted `wss` protocol, and has exactly the same interface as a socket you would use in a web browser. On the wire it identifies itself as `hybi-13`. ```ruby require 'faye/websocket' require 'eventmachine' EM.run { ws = Faye::WebSocket::Client.new('ws://www.example.com/') ws.on :open do |event| p [:open] ws.send('Hello, world!') end ws.on :message do |event| p [:message, event.data] end ws.on :close do |event| p [:close, event.code, event.reason] ws = nil end } ``` ## Subprotocol negotiation The WebSocket protocol allows peers to select and identify the application protocol to use over the connection. On the client side, you can set which protocols the client accepts by passing a list of protocol names when you construct the socket: ```ruby ws = Faye::WebSocket::Client.new('ws://www.example.com/', ['irc', 'amqp']) ``` On the server side, you can likewise pass in the list of protocols the server supports after the other constructor arguments: ```ruby ws = Faye::WebSocket.new(env, ['irc', 'amqp']) ``` If the client and server agree on a protocol, both the client- and server-side socket objects expose the selected protocol through the `ws.protocol` property. ## WebSocket API Both the server- and client-side `WebSocket` objects support the following API: * `on(:open) { |event| }` fires when the socket connection is established. Event has no attributes. * `onerror` fires when the connection attempt fails. Event has no attributes. * `on(:message) { |event| }` fires when the socket receives a message. Event has one attribute, `data`, which is either a `String` (for text frames) or an `Array` of byte-sized integers (for binary frames). * `on(:error) { |event| }` fires when there is a protocol error due to bad data sent by the other peer. This event is purely informational, you do not need to implement error recovery. * `on(:close) { |event| }` fires when either the client or the server closes the connection. Event has two optional attributes, `code` and `reason`, that expose the status code and message sent by the peer that closed the connection. * `send(message)` accepts either a `String` or an `Array` of byte-sized integers and sends a text or binary message over the connection to the other peer. * `ping(message = '', &callback)` sends a ping frame with an optional message and fires the callback when a matching pong is received. * `close` closes the connection. * `version` is a string containing the version of the `WebSocket` protocol the connection is using. * `protocol` is a string (which may be empty) identifying the subprotocol the socket is using. ## Handling EventSource connections in Rack EventSource connections provide a very similar interface, although because they only allow the server to send data to the client, there is no `onmessage` API. EventSource allows the server to push text messages to the client, where each message has an optional event-type and ID. ```ruby # app.rb require 'faye/websocket' App = lambda do |env| if Faye::EventSource.eventsource?(env) es = Faye::EventSource.new(env) p [:open, es.url, es.last_event_id] # Periodically send messages loop = EM.add_periodic_timer(1) { es.send('Hello') } es.on :close do |event| EM.cancel_timer(loop) es = nil end # Return async Rack response es.rack_response else # Normal HTTP request [200, {'Content-Type' => 'text/plain'}, ['Hello']] end end ``` The `send` method takes two optional parameters, `:event` and `:id`. The default event-type is `'message'` with no ID. For example, to send a `notification` event with ID `99`: ```ruby es.send('Breaking News!', :event => 'notification', :id => '99') ``` The `EventSource` object exposes the following properties: * `url` is a string containing the URL the client used to create the EventSource. * `last_event_id` is a string containing the last event ID received by the client. You can use this when the client reconnects after a dropped connection to determine which messages need resending. When you initialize an EventSource with `Faye::EventSource.new`, you can pass configuration options after the `env` parameter. Available options are: * `:retry` is a number that tells the client how long (in seconds) it should wait after a dropped connection before attempting to reconnect. * `:ping` is a number that tells the server how often (in seconds) to send 'ping' packets to the client to keep the connection open, to defeat timeouts set by proxies. The client will ignore these messages. For example, this creates a connection that pings every 15 seconds and is retryable every 10 seconds if the connection is broken: ```ruby es = Faye::EventSource.new(es, :ping => 15, :retry => 10) ``` You can send a ping message at any time by calling `es.ping`. Unlike WebSocket the client does not send a response to this; it is merely to send some data over the wire to keep the connection alive. ## Running your socket application The following describes how to run a WebSocket application using all our supported web servers. ### Running the app with Thin If you use Thin to server your application you need to include this line after loading `faye/websocket`: ```ruby Faye::WebSocket.load_adapter('thin') ``` Thin can be started via the command line if you've set up a `config.ru` file for your application: ``` $ thin start -R config.ru -p 9292 ``` Or, you can use `rackup`. In development mode, this adds middlewares that don't work with async apps, so you must start it in production mode: ``` $ rackup config.ru -s thin -E production -p 9292 ``` It can also be started using the `Rack::Handler` interface common to many Ruby servers. It must be run using EventMachine, and you can configure Thin further in a block passed to `run`: ```ruby require 'eventmachine' require 'rack' require 'thin' require './app' Faye::WebSocket.load_adapter('thin') EM.run { thin = Rack::Handler.get('thin') thin.run(App, :Port => 9292) do |server| # You can set options on the server here, for example to set up SSL: server.ssl_options = { :private_key_file => 'path/to/ssl.key', :cert_chain_file => 'path/to/ssl.crt' } server.ssl = true end } ``` ### Running the app with Puma Puma has a command line interface for starting your application: ``` $ puma config.ru -p 9292 ``` ### Running the app with Rainbows If you're using version 4.4 or lower of Rainbows, you need to run it with the EventMachine backend and enable the adapter. Put this in your `rainbows.conf` file: ```ruby Rainbows! { use :EventMachine } ``` And make sure you load the adapter in your application: ```ruby Faye::WebSocket.load_adapter('rainbows') ``` Version 4.5 of Rainbows does not need this adapter. You can run your `config.ru` file from the command line. Again, `Rack::Lint` will complain unless you put the application in production mode. ``` $ rainbows config.ru -c path/to/rainbows.conf -E production -p 9292 ``` ### Running the app with Goliath If you use Goliath to server your application you need to include this line after loading `faye/websocket`: ```ruby Faye::WebSocket.load_adapter('goliath') ``` Goliath can be made to run arbitrary Rack apps by delegating to them from a `Goliath::API` instance. A simple server looks like this: ```ruby require 'goliath' require './app' Faye::WebSocket.load_adapter('goliath') class EchoServer < Goliath::API def response(env) App.call(env) end end ``` `Faye::WebSocket` can also be used inline within a Goliath app: ```ruby require 'goliath' require 'faye/websocket' Faye::WebSocket.load_adapter('goliath') class EchoServer < Goliath::API def response(env) ws = Faye::WebSocket.new(env) ws.on :message do |event| ws.send(event.data) end ws.rack_response end end ``` ## License (The MIT License) Copyright (c) 2010-2013 James Coglan Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.