WebSocket Client & Server Implementation for Node

Overview

This is a (mostly) pure JavaScript implementation of the WebSocket protocol versions 8 and 13 for Node. There are some example client and server applications that implement various interoperability testing protocols in the "test/scripts" folder.

For a WebSocket client written in ActionScript 3, see my AS3WebScocket project.

Documentation

You can read the full API documentation in the docs folder.

Changelog

Current Version: 1.0.21 — Released 2015-07-22

Version 1.0.21

• Incrememnted and re-published to work around an aborted npm publish of v1.0.20.

Version 1.0.20

• Added EventTarget to the W3CWebSocket interface (Thanks, @ibc!)
• Corrected an inaccurate error message. (Thanks, @lekoaf!)

Version 1.0.19

• Updated to nan v1.8.x (tested with v1.8.4)
• Added "license": "Apache-2.0" to package.json via pull request #199 by @pgilad. See npm1k.org.

View the full changelog

Browser Support

All current browsers are fully supported.

• Firefox 7-9 (Old) (Protocol Version 8)
• Firefox 10+ (Protocol Version 13)
• Chrome 14,15 (Old) (Protocol Version 8)
• Chrome 16+ (Protocol Version 13)
• Internet Explorer 10+ (Protocol Version 13)
• Safari 6+ (Protocol Version 13)

Safari older than 6.0 is not supported since it uses a very old draft of WebSockets

If you need to simultaneously support legacy browser versions that had implemented draft-75/draft-76/draft-00, take a look here: https://gist.github.com/1428579

Benchmarks

There are some basic benchmarking sections in the Autobahn test suite. I've put up a benchmark page that shows the results from the Autobahn tests run against AutobahnServer 0.4.10, WebSocket-Node 1.0.2, WebSocket-Node 1.0.4, and ws 0.3.4.

Autobahn Tests

The very complete Autobahn Test Suite is used by most WebSocket implementations to test spec compliance and interoperability.

• View Server Test Results
• View Client Test Results

Notes

This library has been used in production on worlize.com since April 2011 and seems to be stable. Your mileage may vary.

Tested with the following node versions:

• 0.8.28
• 0.10.33

It may work in earlier or later versions but I'm not actively testing it outside of the listed versions. YMMV.

Installation

A few users have reported difficulties building the native extensions without first manually installing node-gyp. If you have trouble building the native extensions, make sure you've got a C++ compiler, and have done npm install -g node-gyp first.

Native extensions are optional, however, and WebSocket-Node will work even if the extensions cannot be compiled.

In your project root:

$ npm install websocket

Then in your code:

var WebSocketServer = require('websocket').server;
var WebSocketClient = require('websocket').client;
var WebSocketFrame  = require('websocket').frame;
var WebSocketRouter = require('websocket').router;
var W3CWebSocket = require('websocket').w3cwebsocket;

Note for Windows Users

Because there is a small C++ component used for validating UTF-8 data, you will need to install a few other software packages in addition to Node to be able to build this module:

• Microsoft Visual C++
• Python 2.7 (NOT Python 3.x)

Current Features:

• Licensed under the Apache License, Version 2.0
• Protocol version "8" and "13" (Draft-08 through the final RFC) framing and handshake
• Can handle/aggregate received fragmented messages
• Can fragment outgoing messages
• Router to mount multiple applications to various path and protocol combinations
• TLS supported for outbound connections via WebSocketClient
• TLS supported for server connections (use https.createServer instead of http.createServer)
  • Thanks to pors for confirming this!
• Cookie setting and parsing
• Tunable settings
  • Max Receivable Frame Size
  • Max Aggregate ReceivedMessage Size
  • Whether to fragment outgoing messages
  • Fragmentation chunk size for outgoing messages
  • Whether to automatically send ping frames for the purposes of keepalive
  • Keep-alive ping interval
  • Whether or not to automatically assemble received fragments (allows application to handle individual fragments directly)
  • How long to wait after sending a close frame for acknowledgment before closing the socket.
• W3C WebSocket API for applications running on both Node and browsers (via the W3CWebSocket class).

Known Issues/Missing Features:

• No API for user-provided protocol extensions.

Usage Examples

Server Example

Here's a short example showing a server that echos back anything sent to it, whether utf-8 or binary.

#!/usr/bin/env node
var WebSocketServer = require('websocket').server;
var http = require('http');

var server = http.createServer(function(request, response) {
    console.log((new Date()) + ' Received request for ' + request.url);
    response.writeHead(404);
    response.end();
});
server.listen(8080, function() {
    console.log((new Date()) + ' Server is listening on port 8080');
});

wsServer = new WebSocketServer({
    httpServer: server,
    // You should not use autoAcceptConnections for production
    // applications, as it defeats all standard cross-origin protection
    // facilities built into the protocol and the browser.  You should
    // *always* verify the connection's origin and decide whether or not
    // to accept it.
    autoAcceptConnections: false
});

function originIsAllowed(origin) {
  // put logic here to detect whether the specified origin is allowed.
  return true;
}

wsServer.on('request', function(request) {
    if (!originIsAllowed(request.origin)) {
      // Make sure we only accept requests from an allowed origin
      request.reject();
      console.log((new Date()) + ' Connection from origin ' + request.origin + ' rejected.');
      return;
    }
    
    var connection = request.accept('echo-protocol', request.origin);
    console.log((new Date()) + ' Connection accepted.');
    connection.on('message', function(message) {
        if (message.type === 'utf8') {
            console.log('Received Message: ' + message.utf8Data);
            connection.sendUTF(message.utf8Data);
        }
        else if (message.type === 'binary') {
            console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
            connection.sendBytes(message.binaryData);
        }
    });
    connection.on('close', function(reasonCode, description) {
        console.log((new Date()) + ' Peer ' + connection.remoteAddress + ' disconnected.');
    });
});

Client Example

This is a simple example client that will print out any utf-8 messages it receives on the console, and periodically sends a random number.

This code demonstrates a client in Node.js, not in the browser

#!/usr/bin/env node
var WebSocketClient = require('websocket').client;

var client = new WebSocketClient();

client.on('connectFailed', function(error) {
    console.log('Connect Error: ' + error.toString());
});

client.on('connect', function(connection) {
    console.log('WebSocket Client Connected');
    connection.on('error', function(error) {
        console.log("Connection Error: " + error.toString());
    });
    connection.on('close', function() {
        console.log('echo-protocol Connection Closed');
    });
    connection.on('message', function(message) {
        if (message.type === 'utf8') {
            console.log("Received: '" + message.utf8Data + "'");
        }
    });
    
    function sendNumber() {
        if (connection.connected) {
            var number = Math.round(Math.random() * 0xFFFFFF);
            connection.sendUTF(number.toString());
            setTimeout(sendNumber, 1000);
        }
    }
    sendNumber();
});

client.connect('ws://localhost:8080/', 'echo-protocol');

Client Example using the W3C WebSocket API

Same example as above but using the W3C WebSocket API.

var W3CWebSocket = require('websocket').w3cwebsocket;

var client = new W3CWebSocket('ws://localhost:8080/', 'echo-protocol');

client.onerror = function() {
    console.log('Connection Error');
};

client.onopen = function() {
    console.log('WebSocket Client Connected');

    function sendNumber() {
        if (client.readyState === client.OPEN) {
            var number = Math.round(Math.random() * 0xFFFFFF);
            client.send(number.toString());
            setTimeout(sendNumber, 1000);
        }
    }
    sendNumber();
};

client.onclose = function() {
    console.log('echo-protocol Client Closed');
};

client.onmessage = function(e) {
    if (typeof e.data === 'string') {
        console.log("Received: '" + e.data + "'");
    }
};

Request Router Example

For an example of using the request router, see libwebsockets-test-server.js in the test folder.

Resources

A presentation on the state of the WebSockets protocol that I gave on July 23, 2011 at the LA Hacker News meetup. WebSockets: The Real-Time Web, Delivered