socketstream/ss-engine.io

'use strict';

// Engine.io client-side Wrapper
var reconnectSwitch = false;
var reconnectionTimeout = 1000;
var ss = require('socketstream');

// Private

var getCookie = function(c_name) {
  var c_end, c_start;
  if (document.cookie.length > 0) {
    c_start = document.cookie.indexOf(c_name + '=');
    if (c_start !== -1) {
      c_start = c_start + c_name.length + 1;
      c_end = document.cookie.indexOf(';', c_start);
      if (c_end === -1) { c_end = document.cookie.length; }
      return unescape(document.cookie.substring(c_start, c_end));
    }
  }
  return '';
};

module.exports = function(serverStatus, message, config) {

  if (JSON.stringify(config) === '{}') {
    config = { 
        secure  : document.location.protocol === 'https:',
        host    : document.location.hostname,
        port    : document.location.protocol === 'https:' ? 443 : document.location.port
    };
  }

  return {
    connect: function(){
      var sock = new eio.Socket(config);

      sock.on('open', function() {
        var sessionId = getCookie('connect.sid');
        if (sessionId) {
          sock.send('X|' + sessionId);
        } else{
          console.error('Unable to obtain session ID');
        }
      });
     
      sock.on('message', function (e) {

        var i, x, msg = e;

        // Attempt to get the responderId from each message
        if ( (i = msg.indexOf('|')) > 0) {

          var responderId = msg.substr(0, i), 
                  content = msg.substr(i+1);

          switch (responderId) {

            // X = a system message
            case 'X':
              if (reconnectSwitch === false) {
                serverStatus.emit('ready');
              } else {
                reconnectionTimeout = 1000;
                serverStatus.emit('reconnect');
              }
              break;

            // 0 = incoming events
            // As events are so integral to SocketStream rather than breaking up the JSON message
            // sent over the event transport for efficiencies sake we append the meta data (typically 
            // the channel name) at the end of the JSON message after the final pipe | character
            case '0':
              if ( (x = content.lastIndexOf('|')) > 0) {
                var event = content.substr(0, x),
                     meta = content.substr(x+1);
                message.emit(responderId, event, meta);
              } else {
                console.error('Invalid event message received:', msg);
              }
              break;
            
            // All other messages are passed directly to the relevant Request Responder
            default:
              message.emit(responderId, content);
          }

        // EVERY message should have a responderId
        // If we can't find one, it's a malformed request
        } else {
          console.error('Invalid websocket message received:', msg);
        }

      });

      var attemptReconnect = function(time){
        setTimeout(function(){
          ss.assignTransport(config);
          if (ss.server.event !== 'reconnect') {
            reconnectionTimeout *= 1.5;
          }
        }, time);
        clearTimeout();
      };

      sock.on('close', function() {
        reconnectSwitch = true;
        serverStatus.emit('disconnect');
        attemptReconnect(reconnectionTimeout);
      });

      // Return a function which is used to send all messages to the server
      return sock.send; // (receives msg object)
    }
  };
};