transport.js

/**
 * socket.io
 * Copyright(c) 2011 LearnBoost <dev@learnboost.com>
 * MIT Licensed
 */

(function (exports, io) {

  /**
   * Expose constructor.
   */

  exports.Transport = Transport;

  /**
   * This is the transport template for all supported transport methods.
   *
   * @constructor
   * @api public
   */

  function Transport (socket, sessid) {
    this.socket = socket;
    this.sessid = sessid;
  };

  /**
   * Apply EventEmitter mixin.
   */

  io.util.mixin(Transport, io.EventEmitter);


  /**
   * Indicates whether heartbeats is enabled for this transport
   *
   * @api private
   */

  Transport.prototype.heartbeats = function () {
    return true;
  };

  /**
   * Handles the response from the server. When a new response is received
   * it will automatically update the timeout, decode the message and
   * forwards the response to the onMessage function for further processing.
   *
   * @param {String} data Response from the server.
   * @api private
   */

  Transport.prototype.onData = function (data) {
    this.clearCloseTimeout();

    // If the connection in currently open (or in a reopening state) reset the close
    // timeout since we have just received data. This check is necessary so
    // that we don't reset the timeout on an explicitly disconnected connection.
    if (this.socket.connected || this.socket.connecting || this.socket.reconnecting) {
      this.setCloseTimeout();
    }

    if (data !== '') {
      // todo: we should only do decodePayload for xhr transports
      var msgs = io.parser.decodePayload(data);

      if (msgs && msgs.length) {
        for (var i = 0, l = msgs.length; i < l; i++) {
          this.onPacket(msgs[i]);
        }
      }
    }

    return this;
  };

  /**
   * Handles packets.
   *
   * @api private
   */

  Transport.prototype.onPacket = function (packet) {
    this.socket.setHeartbeatTimeout();

    if (packet.type == 'heartbeat') {
      return this.onHeartbeat();
    }

    if (packet.type == 'connect' && packet.endpoint == '') {
      this.onConnect();
    }

    if (packet.type == 'error' && packet.advice == 'reconnect') {
      this.isOpen = false;
    }

    this.socket.onPacket(packet);

    return this;
  };

  /**
   * Sets close timeout
   *
   * @api private
   */

  Transport.prototype.setCloseTimeout = function () {
    if (!this.closeTimeout) {
      var self = this;

      this.closeTimeout = setTimeout(function () {
        self.onDisconnect();
      }, this.socket.closeTimeout);
    }
  };

  /**
   * Called when transport disconnects.
   *
   * @api private
   */

  Transport.prototype.onDisconnect = function () {
    if (this.isOpen) this.close();
    this.clearTimeouts();
    this.socket.onDisconnect();
    return this;
  };

  /**
   * Called when transport connects
   *
   * @api private
   */

  Transport.prototype.onConnect = function () {
    this.socket.onConnect();
    return this;
  };

  /**
   * Clears close timeout
   *
   * @api private
   */

  Transport.prototype.clearCloseTimeout = function () {
    if (this.closeTimeout) {
      clearTimeout(this.closeTimeout);
      this.closeTimeout = null;
    }
  };

  /**
   * Clear timeouts
   *
   * @api private
   */

  Transport.prototype.clearTimeouts = function () {
    this.clearCloseTimeout();

    if (this.reopenTimeout) {
      clearTimeout(this.reopenTimeout);
    }
  };

  /**
   * Sends a packet
   *
   * @param {Object} packet object.
   * @api private
   */

  Transport.prototype.packet = function (packet) {
    this.send(io.parser.encodePacket(packet));
  };

  /**
   * Send the received heartbeat message back to server. So the server
   * knows we are still connected.
   *
   * @param {String} heartbeat Heartbeat response from the server.
   * @api private
   */

  Transport.prototype.onHeartbeat = function (heartbeat) {
    this.packet({ type: 'heartbeat' });
  };

  /**
   * Called when the transport opens.
   *
   * @api private
   */

  Transport.prototype.onOpen = function () {
    this.isOpen = true;
    this.clearCloseTimeout();
    this.socket.onOpen();
  };

  /**
   * Notifies the base when the connection with the Socket.IO server
   * has been disconnected.
   *
   * @api private
   */

  Transport.prototype.onClose = function () {
    var self = this;

    /* FIXME: reopen delay causing a infinit loop
    this.reopenTimeout = setTimeout(function () {
      self.open();
    }, this.socket.options['reopen delay']);*/

    this.isOpen = false;
    this.socket.onClose();
    this.onDisconnect();
  };

  /**
   * Generates a connection url based on the Socket.IO URL Protocol.
   * See <https://github.com/learnboost/socket.io-node/> for more details.
   *
   * @returns {String} Connection url
   * @api private
   */

  Transport.prototype.prepareUrl = function () {
    var options = this.socket.options;

    return this.scheme() + '://'
      + options.host + ':' + options.port + '/'
      + options.resource + '/' + io.protocol
      + '/' + this.name + '/' + this.sessid;
  };

  /**
   * Checks if the transport is ready to start a connection.
   *
   * @param {Socket} socket The socket instance that needs a transport
   * @param {Function} fn The callback
   * @api private
   */

  Transport.prototype.ready = function (socket, fn) {
    fn.call(this);
  };
})(
    'undefined' != typeof io ? io : module.exports
  , 'undefined' != typeof io ? io : module.parent.exports
);