faye/src/transport/transport.js

Simple pub/sub messaging for the web

'use strict';

var Class    = require('../util/class'),
    Cookie   = require('../util/cookies').Cookie,
    Promise  = require('../util/promise'),
    array    = require('../util/array'),
    assign   = require('../util/assign'),
    Logging  = require('../mixins/logging'),
    Timeouts = require('../mixins/timeouts'),
    Channel  = require('../protocol/channel');

var Transport = assign(Class({ className: 'Transport',
  DEFAULT_PORTS: { 'http:': 80, 'https:': 443, 'ws:': 80, 'wss:': 443 },
  MAX_DELAY:     0,

  batching:  true,

  initialize: function(dispatcher, endpoint) {
    this._dispatcher = dispatcher;
    this.endpoint    = endpoint;
    this._outbox     = [];
    this._proxy      = assign({}, this._dispatcher.proxy);

    if (!this._proxy.origin)
      this._proxy.origin = this._findProxy();
  },

  close: function() {},

  encode: function(messages) {
    return '';
  },

  sendMessage: function(message) {
    this.debug('Client ? sending message to ?: ?',
               this._dispatcher.clientId, this.endpoint.href, message);

    if (!this.batching) return Promise.resolve(this.request([message]));

    this._outbox.push(message);
    this._flushLargeBatch();

    if (message.channel === Channel.HANDSHAKE)
      return this._publish(0.01);

    if (message.channel === Channel.CONNECT)
      this._connectMessage = message;

    return this._publish(this.MAX_DELAY);
  },

  _makePromise: function() {
    var self = this;

    this._requestPromise = this._requestPromise || new Promise(function(resolve) {
      self._resolvePromise = resolve;
    });
  },

  _publish: function(delay) {
    this._makePromise();

    this.addTimeout('publish', delay, function() {
      this._flush();
      delete this._requestPromise;
    }, this);

    return this._requestPromise;
  },

  _flush: function() {
    this.removeTimeout('publish');

    if (this._outbox.length > 1 && this._connectMessage)
      this._connectMessage.advice = { timeout: 0 };

    this._resolvePromise(this.request(this._outbox));

    this._connectMessage = null;
    this._outbox = [];
  },

  _flushLargeBatch: function() {
    var string = this.encode(this._outbox);
    if (string.length < this._dispatcher.maxRequestSize) return;
    var last = this._outbox.pop();

    this._makePromise();
    this._flush();

    if (last) this._outbox.push(last);
  },

  _receive: function(replies) {
    if (!replies) return;
    replies = [].concat(replies);

    this.debug('Client ? received from ? via ?: ?',
               this._dispatcher.clientId, this.endpoint.href, this.connectionType, replies);

    for (var i = 0, n = replies.length; i < n; i++)
      this._dispatcher.handleResponse(replies[i]);
  },

  _handleError: function(messages, immediate) {
    messages = [].concat(messages);

    this.debug('Client ? failed to send to ? via ?: ?',
               this._dispatcher.clientId, this.endpoint.href, this.connectionType, messages);

    for (var i = 0, n = messages.length; i < n; i++)
      this._dispatcher.handleError(messages[i]);
  },

  _getCookies: function() {
    var cookies = this._dispatcher.cookies,
        url     = this.endpoint.href;

    if (!cookies) return '';

    return array.map(cookies.getCookiesSync(url), function(cookie) {
      return cookie.cookieString();
    }).join('; ');
  },

  _storeCookies: function(setCookie) {
    var cookies = this._dispatcher.cookies,
        url     = this.endpoint.href,
        cookie;

    if (!setCookie || !cookies) return;
    setCookie = [].concat(setCookie);

    for (var i = 0, n = setCookie.length; i < n; i++) {
      cookie = Cookie.parse(setCookie[i]);
      cookies.setCookieSync(cookie, url);
    }
  },

  _findProxy: function() {
    if (typeof process === 'undefined') return undefined;

    var protocol = this.endpoint.protocol;
    if (!protocol) return undefined;

    var name   = protocol.replace(/:$/, '').toLowerCase() + '_proxy',
        upcase = name.toUpperCase(),
        env    = process.env,
        keys, proxy;

    if (name === 'http_proxy' && env.REQUEST_METHOD) {
      keys = Object.keys(env).filter(function(k) { return /^http_proxy$/i.test(k) });
      if (keys.length === 1) {
        if (keys[0] === name && env[upcase] === undefined)
          proxy = env[name];
      } else if (keys.length > 1) {
        proxy = env[name];
      }
      proxy = proxy || env['CGI_' + upcase];
    } else {
      proxy = env[name] || env[upcase];
      if (proxy && !env[name])
        console.warn('The environment variable ' + upcase +
                     ' is discouraged. Use ' + name + '.');
    }
    return proxy;
  }

}), {
  get: function(dispatcher, allowed, disabled, callback, context) {
    var endpoint = dispatcher.endpoint;

    array.asyncEach(this._transports, function(pair, resume) {
      var connType     = pair[0], klass = pair[1],
          connEndpoint = dispatcher.endpointFor(connType);

      if (array.indexOf(disabled, connType) >= 0)
        return resume();

      if (array.indexOf(allowed, connType) < 0) {
        klass.isUsable(dispatcher, connEndpoint, function() {});
        return resume();
      }

      klass.isUsable(dispatcher, connEndpoint, function(isUsable) {
        if (!isUsable) return resume();
        var transport = klass.hasOwnProperty('create') ? klass.create(dispatcher, connEndpoint) : new klass(dispatcher, connEndpoint);
        callback.call(context, transport);
      });
    }, function() {
      throw new Error('Could not find a usable connection type for ' + endpoint.href);
    });
  },

  register: function(type, klass) {
    this._transports.push([type, klass]);
    klass.prototype.connectionType = type;
  },

  getConnectionTypes: function() {
    return array.map(this._transports, function(t) { return t[0] });
  },

  disable: function(feature) {
    if (feature !== 'autodisconnect') return;

    for (var i = 0; i < this._transports.length; i++)
      this._transports[i][1]._unloaded = false;
  },

  _transports: []
});

assign(Transport.prototype, Logging);
assign(Transport.prototype, Timeouts);

module.exports = Transport;