wsEngine option and env var, defaults to 'ws'

Author: kapouer

lib/server.js

@@ -11,7 +11,6 @@ var qs = require('querystring')
   , transports = require('./transports')
   , EventEmitter = require('events').EventEmitter
   , Socket = require('./socket')
-  , WebSocketServer = require('ws').Server
   , debug = require('debug')('engine');
 
 /**
@@ -36,6 +35,8 @@ function Server(opts){
   this.clientsCount = 0;
 
   opts = opts || {};
+
+  this.wsEngine = opts.wsEngine || process.env.EIO_WS_ENGINE || 'ws';
   this.pingTimeout = opts.pingTimeout || 60000;
   this.pingInterval = opts.pingInterval || 25000;
   this.upgradeTimeout = opts.upgradeTimeout || 10000;
@@ -69,6 +70,7 @@ function Server(opts){
 
   // initialize websocket server
   if (~this.transports.indexOf('websocket')) {
+    var WebSocketServer = require(this.wsEngine).Server;
     this.ws = new WebSocketServer({
       noServer: true,
       clientTracking: false,