Index: lams_learning/web/includes/javascript/presence.js
===================================================================
RCS file: /usr/local/cvsroot/lams_learning/web/includes/javascript/presence.js,v
diff -u -r1.4.2.5 -r1.4.2.6
--- lams_learning/web/includes/javascript/presence.js	8 Nov 2016 02:43:08 -0000	1.4.2.5
+++ lams_learning/web/includes/javascript/presence.js	24 May 2017 05:42:25 -0000	1.4.2.6
@@ -72,7 +72,8 @@
 				if (listing.length == 0){
 					// create listing div
 					var listingDiv = $('<div id="' + listingName
-							            + '" onClick="javascript:roster.handleUserClicked(' + localId + ');" class="presenceListing">'
+							            + '" onClick="javascript:roster.handleUserClicked(' 
+							            + localId + ');" class="presenceListing">'
 							            + createPresenceListing(nick, tag)
 							            + '</div>');
 					
@@ -90,62 +91,91 @@
 	},
 	
 	// init the connection with server using server URL but with different protocol
-	presenceWebsocket = new WebSocket(APP_URL.replace('http', 'ws') + 'presenceChatWebsocket?lessonID=' + lessonId + 
-															   '&imEnabled=' + presenceImEnabled + '&nickname=' + encodeURIComponent(nickname));
-
-// when the server pushes new messages and roster to the learner's browser
-presenceWebsocket.onmessage = function(e){
-	// create JSON object
-  var input = JSON.parse(e.data);
-  if (input.roster) {
-	  roster.updateDisplay(input.roster);
-  }
-  
-  if (input.messages) {
-	  var activeNick = getUserFromTabIndex(presenceChatTabs.tabs('option','active')),
-	  	  selectedTabTag = nickToTag(activeNick);
+	presenceWebsocket = new WebSocket(APP_URL.replace('http', 'ws') + 'presenceChatWebsocket?lessonID=' + lessonId 
+															   + '&imEnabled=' + presenceImEnabled 
+															   + '&nickname=' + encodeURIComponent(nickname)),
+	presenceWebsocketPingTimeout = null,
+	presenceWebsocketPingFunc = null;
+	
+	presenceWebsocketPingFunc = function(skipPing){
+		if (presenceWebsocket.readyState == presenceWebsocket.CLOSING 
+				|| presenceWebsocket.readyState == presenceWebsocket.CLOSED){
+			location.reload();
+		}
+		
+		// check and ping every 3 minutes
+		presenceWebsocketPingTimeout = setTimeout(presenceWebsocketPingFunc, 3*60*1000);
+		// initial set up does not send ping
+		if (!skipPing) {
+			presenceWebsocket.send("ping");
+		}
+	};
+	// set up timer for the first time
+	presenceWebsocketPingFunc(true);
+	
+	presenceWebsocket.onclose = function(e){
+		// react only on abnormal close
+		if (e.code === 1006) {
+			location.reload();
+		}
+	};
+	// when the server pushes new messages and roster to the learner's browser
+	presenceWebsocket.onmessage = function(e){
+	  // reset ping timer
+      clearTimeout(presenceWebsocketPingTimeout);
+      presenceWebsocketPingFunc(true);
+		
+	  // create JSON object
+	  var input = JSON.parse(e.data);
+	  if (input.roster) {
+		  roster.updateDisplay(input.roster);
+	  }
 	  
-	  jQuery.each(input.messages, function(){
-		  // which tab are we talking about?
-		  var from = this.to ? (this.from == nickname ? this.to : this.from) : groupChatInfo.nick,
-			  lastMessageUid = roster.lastMessageUids[from] || 0;
+	  if (input.messages) {
+		  var activeNick = getUserFromTabIndex(presenceChatTabs.tabs('option','active')),
+		  	  selectedTabTag = nickToTag(activeNick);
 		  
-		  // are the messages new?
-		  if (this.uid > lastMessageUid) {
-			  var tag = nickToTag(from);
-			  if (tag != selectedTabTag) {
-				var tab = $("#" + tagToTabLabel(tag));
-				if (tab.length == 0) {
-					// no tab opened yet, create it
-					tab = addTab(from, tag);
-				}
-				
-				// notify of new message
-				tab.addClass('presenceTabNewMessage');
-				if (tag != groupChatInfo.tag) {
-					$("#" + tagToListing(tag)).addClass('presenceListingNewMessage');
-				}
-			  }
+		  jQuery.each(input.messages, function(){
+			  // which tab are we talking about?
+			  var from = this.to ? (this.from == nickname ? this.to : this.from) : groupChatInfo.nick,
+				  lastMessageUid = roster.lastMessageUids[from] || 0;
 			  
-			  roster.lastMessageUids[from] = this.uid;
-			  var messageArea = $("#" + (nickToMessageArea(from)));
-			  messageArea.append(generateMessageHTML(this.from, this.message, this.dateSent));
-			  messageArea.scrollTop(messageArea.prop('scrollHeight'));
-		  }
-	  });  
-  }
-  
-	// remove conversation tabs with learners who are gone
-	$('li a', presenceChatTabs).each(function() {
-	  var nick = $(this).text();
-	  if (nick != groupChatInfo.nick && !roster.users[nick]) {
-		  var tag = $(this).attr('href');
-		  $(tag).remove();
-		  $(this).parent().remove();
-		  presenceChatTabs.tabs('refresh');
+			  // are the messages new?
+			  if (this.uid > lastMessageUid) {
+				  var tag = nickToTag(from);
+				  if (tag != selectedTabTag) {
+					var tab = $("#" + tagToTabLabel(tag));
+					if (tab.length == 0) {
+						// no tab opened yet, create it
+						tab = addTab(from, tag);
+					}
+					
+					// notify of new message
+					tab.addClass('presenceTabNewMessage');
+					if (tag != groupChatInfo.tag) {
+						$("#" + tagToListing(tag)).addClass('presenceListingNewMessage');
+					}
+				  }
+				  
+				  roster.lastMessageUids[from] = this.uid;
+				  var messageArea = $("#" + (nickToMessageArea(from)));
+				  messageArea.append(generateMessageHTML(this.from, this.message, this.dateSent));
+				  messageArea.scrollTop(messageArea.prop('scrollHeight'));
+			  }
+		  });  
 	  }
-	});
-};
+	  
+		// remove conversation tabs with learners who are gone
+		$('li a', presenceChatTabs).each(function() {
+		  var nick = $(this).text();
+		  if (nick != groupChatInfo.nick && !roster.users[nick]) {
+			  var tag = $(this).attr('href');
+			  $(tag).remove();
+			  $(this).parent().remove();
+			  presenceChatTabs.tabs('refresh');
+		  }
+		});
+	};
 
 });
 
@@ -276,6 +306,10 @@
 		};
 	
 	presenceWebsocket.send(JSON.stringify(data));
+	
+	// reset ping timer
+    clearTimeout(presenceWebsocketPingTimeout);
+    presenceWebsocketPingFunc(true);
 }
 
 /* ******* Click handlers ******* */