engine.io-client

Engine.IO client

This is the client for Engine, the implementation of transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO.

Hello World

<script src="/path/to/engine.js"></script>
<script>
  var socket = new eio.Socket({ host: 'localhost', port: 80 });
  socket.onopen = function () {
    socket.onmessage = function (data) { });
    socket.onclose = function () { });
  };
</script>

Features

• Lightweight
  • Lazyloads Flash transport
• Isomorphic with WebSocket API
• Written for node, runs on browser thanks to browserbuild
  • Maximizes code readability / maintenance.
  • Simplifies testing.
• Transports are independent of Engine
  • Easy to debug
  • Easy to unit test
• Runs inside HTML5 WebWorker

API

---

Top-level

These are exposed in the eio global namespace (in the browser), or by require('engine.io-client') (in Node.JS).

Properties

• version (String): client version
• protocol (Number): protocol revision number
• Socket (Function): client constructor

Socket

The client class. Inherits from EventEmitter.

Properties

• onopen (Function)
  • open event handler
• onmessage (Function)
  • message event handler
• onclose (Function)
  • message event handler

Events

• open
  • Fired upon successful connection.
• message
  • Fired when data is received from the server.
  • Arguments
    • String: utf-8 encoded data
• close
  • Fired upon disconnection.
• error
  • Fired when an error occurs.

Methods

• constructor
  • Initializes the client
  • Parameters
    • Object: optional, options object
  • Options
    • host (String): host name (localhost)
    • port (Number): port name (80)
    • path (String): path to intercept requests to (/engine.io)
    • resource (String): name of resource for this server (default). Setting a resource allows you to initialize multiple engine.io endpoints on the same host without them interfering, and without changing the path directly.
    • query (Object): optional query string addition (eg: { a: 'b' })
    • secure (`Boolean): whether the connection is secure
    • upgrade (Boolean): defaults to true, whether the client should try to upgrade the transport from long-polling to something better.
    • forceJSONP (Boolean): forces JSONP for polling transport.
    • timestampRequests (Boolean): whether to add the timestamp with each transport request. Note: this is ignored if the browser is IE or Android, in which case requests are always stamped (false)
    • timestampParam (String): timestamp parameter (t)
    • flashPath (String): path to flash client files with trailing slash
    • policyPort (Number): port the policy server listens on (843)
    • transports (Array): a list of transports to try (in order). Defaults to ['polling', 'websocket', 'flashsocket']. Engine always attempts to connect directly with the first one, provided the feature detection test for it passes.
• send
  • Sends a message to the server
  • Parameters
    • String: data to send
• close
  • Disconnects the client.

Transport

The transport class. Private. Inherits from EventEmitter.

Events

• poll: emitted by polling transports upon starting a new request
• pollComplete: emitted by polling transports upon completing a request
• drain: emitted by polling transports upon a buffer drain

Flash transport

In order for the Flash transport to work correctly, ensure the flashPath property points to the location where the files web_socket.js, swfobject.js and WebSocketMainInsecure.swf are located.

Tests

engine.io-client is used to test engine

Support

The support channels for engine.io-client are the same as socket.io:

• irc.freenode.net #socket.io
• Google Groups
• Website

Development

To contribute patches, run tests or benchmarks, make sure to clone the repository:

git clone git://github.com/LearnBoost/engine.io-client.git

Then:

cd engine.io-client
npm install

License

(The MIT License)

Copyright (c) 2011 Guillermo Rauch <guillermo@learnboost.com>

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.