faye/src/transport/web_socket.js

Simple pub/sub messaging for the web

'use strict';

var Class      = require('../util/class'),
    Promise    = require('../util/promise'),
    Set        = require('../util/set'),
    URI        = require('../util/uri'),
    browser    = require('../util/browser'),
    copyObject = require('../util/copy_object'),
    assign     = require('../util/assign'),
    toJSON     = require('../util/to_json'),
    ws         = require('../util/websocket'),
    Deferrable = require('../mixins/deferrable'),
    Transport  = require('./transport');

var WebSocket = assign(Class(Transport, {
  UNCONNECTED:  1,
  CONNECTING:   2,
  CONNECTED:    3,

  batching:     false,

  isUsable: function(callback, context) {
    this.callback(function() { callback.call(context, true) });
    this.errback(function() { callback.call(context, false) });
    this.connect();
  },

  request: function(messages) {
    this._pending = this._pending || new Set();
    for (var i = 0, n = messages.length; i < n; i++) this._pending.add(messages[i]);

    var self = this;

    var promise = new Promise(function(resolve, reject) {
      self.callback(function(socket) {
        if (!socket || socket.readyState !== 1) return;
        socket.send(toJSON(messages));
        resolve(socket);
      });

      self.connect();
    });

    return {
      abort: function() { promise.then(function(ws) { ws.close() }) }
    };
  },

  connect: function() {
    if (WebSocket._unloaded) return;

    this._state = this._state || this.UNCONNECTED;
    if (this._state !== this.UNCONNECTED) return;
    this._state = this.CONNECTING;

    var socket = this._createSocket();
    if (!socket) return this.setDeferredStatus('failed');

    var self = this;

    socket.onopen = function() {
      if (socket.headers) self._storeCookies(socket.headers['set-cookie']);
      self._socket = socket;
      self._state = self.CONNECTED;
      self._everConnected = true;
      self.setDeferredStatus('succeeded', socket);
    };

    var closed = false;
    socket.onclose = socket.onerror = function() {
      if (closed) return;
      closed = true;

      var wasConnected = (self._state === self.CONNECTED);
      socket.onopen = socket.onclose = socket.onerror = socket.onmessage = null;

      delete self._socket;
      self._state = self.UNCONNECTED;

      var pending = self._pending ? self._pending.toArray() : [];
      delete self._pending;

      if (wasConnected || self._everConnected) {
        self.setDeferredStatus('unknown');
        self._handleError(pending, wasConnected);
      } else {
        self.setDeferredStatus('failed');
      }
    };

    socket.onmessage = function(event) {
      var replies;
      try { replies = JSON.parse(event.data) } catch (error) {}

      if (!replies) return;

      replies = [].concat(replies);

      for (var i = 0, n = replies.length; i < n; i++) {
        if (replies[i].successful === undefined) continue;
        self._pending.remove(replies[i]);
      }
      self._receive(replies);
    };
  },

  close: function() {
    if (!this._socket) return;
    this._socket.close();
  },

  _createSocket: function() {
    var url        = WebSocket.getSocketUrl(this.endpoint),
        headers    = this._dispatcher.headers,
        extensions = this._dispatcher.wsExtensions,
        cookie     = this._getCookies(),
        tls        = this._dispatcher.tls,
        options    = { extensions: extensions, headers: headers, proxy: this._proxy, tls: tls };

    if (cookie !== '') options.headers['Cookie'] = cookie;

    try {
      return ws.create(url, [], options);
    } catch (e) {
      // catch CSP error to allow transport to fallback to next connType
    }
  }

}), {
  PROTOCOLS: {
    'http:':  'ws:',
    'https:': 'wss:'
  },

  create: function(dispatcher, endpoint) {
    var sockets = dispatcher.transports.websocket = dispatcher.transports.websocket || {};
    sockets[endpoint.href] = sockets[endpoint.href] || new this(dispatcher, endpoint);
    return sockets[endpoint.href];
  },

  getSocketUrl: function(endpoint) {
    endpoint = copyObject(endpoint);
    endpoint.protocol = this.PROTOCOLS[endpoint.protocol];
    return URI.stringify(endpoint);
  },

  isUsable: function(dispatcher, endpoint, callback, context) {
    this.create(dispatcher, endpoint).isUsable(callback, context);
  }
});

assign(WebSocket.prototype, Deferrable);

if (browser.Event && global.onbeforeunload !== undefined) {
  browser.Event.on(global, 'beforeunload', function() {
    if (WebSocket._unloaded === undefined)
      WebSocket._unloaded = true;
  });
}

module.exports = WebSocket;