js/tcp-client.js

   1 /*
   2 Copyright 2012 Google Inc.
   3
   4 Licensed under the Apache License, Version 2.0 (the "License");
   5 you may not use this file except in compliance with the License.
   6 You may obtain a copy of the License at
   7
   8      http://www.apache.org/licenses/LICENSE-2.0
   9
  10 Unless required by applicable law or agreed to in writing, software
  11 distributed under the License is distributed on an "AS IS" BASIS,
  12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 See the License for the specific language governing permissions and
  14 limitations under the License.
  15
  16 Author: Boris Smus (smus@chromium.org)
  17 */
  18
  19 (function(exports) {
  20
  21   // Define some local variables here.
  22   var socket = chrome.socket;
  23
  24   /**
  25    * Creates an instance of the client
  26    *
  27    * @param {String} host The remote host to connect to
  28    * @param {Number} port The port to connect to at the remote host
  29    */
  30   function TcpClient(host, port) {
  31     this.host = host;
  32     this.port = port;
  33
  34     // Callback functions.
  35     this.callbacks = {
  36       connect: null,    // Called when socket is connected.
  37       disconnect: null, // Called when socket is disconnected.
  38       recv: null,       // Called when client receives data from server.
  39       sent: null        // Called when client sends data to server.
  40     };
  41
  42     // Socket.
  43     this.socketId = null;
  44     this.isConnected = false;
  45
  46     log('initialized tcp client');
  47   }
  48
  49   /**
  50    * Connects to the TCP socket, and creates an open socket.
  51    *
  52    * @see http://developer.chrome.com/apps/socket.html#method-create
  53    * @param {Function} callback The function to call on connection
  54    */
  55   TcpClient.prototype.connect = function(callback) {
  56     socket.create('tcp', {}, this._onCreate.bind(this));
  57
  58     // Register connect callback.
  59     this.callbacks.connect = callback;
  60   };
  61
  62   /**
  63    * Sends a message down the wire to the remote side
  64    *
  65    * @see http://developer.chrome.com/apps/socket.html#method-write
  66    * @param {String} msg The message to send
  67    * @param {Function} callback The function to call when the message has sent
  68    */
  69   TcpClient.prototype.sendMessage = function(msg, callback) {
  70     this._stringToArrayBuffer(msg + '\n', function(arrayBuffer) {
  71       socket.write(this.socketId, arrayBuffer, this._onWriteComplete.bind(this));
  72     }.bind(this));
  73
  74     // Register sent callback.
  75     this.callbacks.sent = callback;
  76   };
  77
  78   /**
  79    * Sets the callback for when a message is received
  80    *
  81    * @param {Function} callback The function to call when a message has arrived
  82    */
  83   TcpClient.prototype.addResponseListener = function(callback) {
  84     // Register received callback.
  85     this.callbacks.recv = callback;
  86   };
  87
  88   /**
  89    * Disconnects from the remote side
  90    *
  91    * @see http://developer.chrome.com/apps/socket.html#method-disconnect
  92    */
  93   TcpClient.prototype.disconnect = function() {
  94     socket.disconnect(this.socketId);
  95     this.isConnected = false;
  96   };
  97
  98   /**
  99    * The callback function used for when we attempt to have Chrome
 100    * create a socket. If the socket is successfully created
 101    * we go ahead and connect to the remote side.
 102    *
 103    * @private
 104    * @see http://developer.chrome.com/apps/socket.html#method-connect
 105    * @param {Object} createInfo The socket details
 106    */
 107   TcpClient.prototype._onCreate = function(createInfo) {
 108     this.socketId = createInfo.socketId;
 109     if (this.socketId > 0) {
 110       socket.connect(this.socketId, this.host, this.port, this._onConnectComplete.bind(this));
 111       this.isConnected = true;
 112     } else {
 113       error('Unable to create socket');
 114     }
 115   };
 116
 117   /**
 118    * The callback function used for when we attempt to have Chrome
 119    * connect to the remote side. If a successful connection is
 120    * made then polling starts to check for data to read
 121    *
 122    * @private
 123    * @param {Number} resultCode Indicates whether the connection was successful
 124    */
 125   TcpClient.prototype._onConnectComplete = function(resultCode) {
 126     // Start polling for reads.
 127     setInterval(this._periodicallyRead.bind(this), 500);
 128
 129     if (this.callbacks.connect) {
 130       log('connect complete');
 131       this.callbacks.connect();
 132     }
 133     log('onConnectComplete');
 134   };
 135
 136   /**
 137    * Checks for new data to read from the socket
 138    *
 139    * @see http://developer.chrome.com/apps/socket.html#method-read
 140    */
 141   TcpClient.prototype._periodicallyRead = function() {
 142     socket.read(this.socketId, null, this._onDataRead.bind(this));
 143   };
 144
 145   /**
 146    * Callback function for when data has been read from the socket.
 147    * Converts the array buffer that is read in to a string
 148    * and sends it on for further processing by passing it to
 149    * the previously assigned callback function.
 150    *
 151    * @private
 152    * @see TcpClient.prototype.addResponseListener
 153    * @param {Object} readInfo The incoming message
 154    */
 155   TcpClient.prototype._onDataRead = function(readInfo) {
 156     // Call received callback if there's data in the response.
 157     if (readInfo.resultCode > 0 && this.callbacks.recv) {
 158       log('onDataRead');
 159       // Convert ArrayBuffer to string.
 160       this._arrayBufferToString(readInfo.data, function(str) {
 161         this.callbacks.recv(str);
 162       }.bind(this));
 163     }
 164   };
 165
 166   /**
 167    * Callback for when data has been successfully
 168    * written to the socket.
 169    *
 170    * @private
 171    * @param {Object} writeInfo The outgoing message
 172    */
 173   TcpClient.prototype._onWriteComplete = function(writeInfo) {
 174     log('onWriteComplete');
 175     // Call sent callback.
 176     if (this.callbacks.sent) {
 177       this.callbacks.sent(writeInfo);
 178     }
 179   };
 180
 181   /**
 182    * Converts an array buffer to a string
 183    *
 184    * @private
 185    * @param {ArrayBuffer} buf The buffer to convert
 186    * @param {Function} callback The function to call when conversion is complete
 187    */
 188   TcpClient.prototype._arrayBufferToString = function(buf, callback) {
 189     var bb = new Blob([new Uint8Array(buf)]);
 190     var f = new FileReader();
 191     f.onload = function(e) {
 192       callback(e.target.result);
 193     };
 194     f.readAsText(bb);
 195   };
 196
 197   /**
 198    * Converts a string to an array buffer
 199    *
 200    * @private
 201    * @param {String} str The string to convert
 202    * @param {Function} callback The function to call when conversion is complete
 203    */
 204   TcpClient.prototype._stringToArrayBuffer = function(str, callback) {
 205     var bb = new Blob([str]);
 206     var f = new FileReader();
 207     f.onload = function(e) {
 208         callback(e.target.result);
 209     };
 210     f.readAsArrayBuffer(bb);
 211   };
 212
 213   /**
 214    * Wrapper function for logging
 215    */
 216   function log(msg) {
 217     //console.log('tcp-client: ', msg);
 218   }
 219
 220   /**
 221    * Wrapper function for error logging
 222    */
 223   function error(msg) {
 224     console.error('tcp-client: ', msg);
 225   }
 226
 227   exports.TcpClient = TcpClient;
 228
 229 })(window);