Added graceful websockets jquery plugin

libraries/external/JQuery-1.4.2/plugins/jquery.gracefulWebSocket.js

@@ -0,0 +1,165 @@
+/**
+ * WebSocket with graceful degradation - jQuery plugin
+ * @author David Lindkvist
+ * @version 0.1
+ * 
+ * Returns an object implementing the WebSocket API. 
+ * 
+ * If browser supports WebSockets a native WebSocket instance is returned. 
+ * If not, a simulated half-duplex implementation is returned which uses polling 
+ * over HTTP to retrieve new messages
+ * 
+ * OPTIONS
+ * -----------------------------------------------------------------------------
+ * 
+ * {Number}		fallbackOpenDelay		number of ms to delay simulated open 
+ * 										event for fallback
+ * {Number}		fallbackPollInterval	number of ms between requests for 
+ * 										fallback polling
+ * {Object}		fallbackPollParams		optional params to pass with each poll 
+ * 										requests
+ * 
+ * EXAMPLES
+ * -----------------------------------------------------------------------------
+ * 
+ * 	var websocket = $.gracefulWebSocket("ws://127.0.0.1:8080/");
+ * 
+ * 	var websocket = $.gracefulWebSocket({
+ * 		fallbackPollParams:  {
+ * 			"latestMessageID": function () {
+ * 				return latestMessageID;
+ * 			}
+ *  	} 
+ * 	});
+ * 
+ */
+
+(function ($) {
+
+	$.extend({
+
+		gracefulWebSocket: function (url, options) {
+
+			// Default properties 
+			this.defaults = {
+				keepAlive: false,		// not implemented - should ping server to keep socket open
+				autoReconnect: false,	// not implemented - should try to reconnect silently if socket is closed
+				fallback: true,			// not implemented - always use HTTP fallback if native browser support is missing
+				fallbackSendURL: url.replace('ws:', 'http:').replace('wss:', 'https:'),
+				fallbackSendMethod: 'POST',
+				fallbackPollURL: url.replace('ws:', 'http:').replace('wss:', 'https:'),
+				fallbackPollMethod: 'GET',
+				fallbackOpenDelay: 100,	// number of ms to delay simulated open event
+				fallbackPollInterval: 3000,	// number of ms between poll requests
+				fallbackPollParams: {}		// optional params to pass with poll requests
+			};
+
+			// Override defaults with user properties
+			var opts = $.extend({}, this.defaults, options);
+
+			/**
+			 * Creates a fallback object implementing the WebSocket interface
+			 */
+			function FallbackSocket() {
+
+				// WebSocket interface constants
+				const CONNECTING = 0;
+				const OPEN = 1;
+				const CLOSING = 2;
+				const CLOSED = 3;
+
+				var pollInterval;
+				var openTimout;
+
+				// create WebSocket object
+				var fws = {
+					// ready state
+					readyState: CONNECTING,
+					bufferedAmount: 0,
+					send: function (data) {
+						var success = true;
+						$.ajax({
+							async: false, // send synchronously
+							type: opts.fallbackSendMethod,
+							url: opts.fallbackSendURL + '?' + $.param( getFallbackParams() ),
+							data: data,
+							dataType: 'text',
+							contentType : "application/x-www-form-urlencoded; charset=utf-8",
+							success: pollSuccess,
+							error: function (xhr) {
+								success = false;
+								$(fws).triggerHandler('error');
+							}
+						});
+						return success;
+					},
+					close: function () {
+						clearTimeout(openTimout);
+						clearInterval(pollInterval);
+						this.readyState = CLOSED;
+						$(fws).triggerHandler('close');
+					},
+					onopen: function () {},
+					onmessage: function () {},
+					onerror: function () {},
+					onclose: function () {},
+					previousRequest: null,
+					currentRequest: null
+				};
+
+				function getFallbackParams() {
+
+					// update timestamp of previous and current poll request
+					fws.previousRequest = fws.currentRequest;					
+					fws.currentRequest = new Date().getTime();
+
+					// extend default params with plugin options
+					return $.extend({"previousRequest": fws.previousRequest, "currentRequest": fws.currentRequest}, opts.fallbackPollParams);
+				}
+
+				/**
+				 * @param {Object} data
+				 */
+				function pollSuccess(data) {
+
+					// trigger onmessage
+					var messageEvent = {"data" : data};
+					fws.onmessage(messageEvent);	
+				}
+
+				function poll() {
+
+					$.ajax({
+						type: opts.fallbackPollMethod,
+						url: opts.fallbackPollURL,
+						dataType: 'text',
+						data: getFallbackParams(),
+						success: pollSuccess,
+						error: function (xhr) {			
+							$(fws).triggerHandler('error');
+						}
+					});		
+				}
+
+				// simulate open event and start polling
+				openTimout = setTimeout(function () { 
+					fws.readyState = OPEN;
+					//fws.currentRequest = new Date().getTime();
+					$(fws).triggerHandler('open');
+					poll();
+					pollInterval = setInterval(poll, opts.fallbackPollInterval);
+
+				}, opts.fallbackOpenDelay);
+
+				// return socket impl
+				return fws;
+			}
+
+			// create a new websocket or fallback
+			var ws = window.WebSocket ? new WebSocket(url) : new FallbackSocket();
+	 		$(window).unload(function () { ws.close(); ws = null });
+			return ws;
+		}
+	});
+
+})(jQuery);