From dda07160531339ed40aa5f687003cc3d15baf245 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Fri, 13 Mar 2015 12:29:55 +0100
Subject: [PATCH] To keep websockets alive send every eight seconds a ping to
 the server.

---
 cmd/mtwebmapper/web/js/auto-update.js | 36 ++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/cmd/mtwebmapper/web/js/auto-update.js b/cmd/mtwebmapper/web/js/auto-update.js
index 89ca8af..bb6b806 100644
--- a/cmd/mtwebmapper/web/js/auto-update.js
+++ b/cmd/mtwebmapper/web/js/auto-update.js
@@ -15,9 +15,7 @@ L.Control.AutoUpdate = L.Control.extend({
         return container;
     },
 
-    cbClick: function (e) {
-        L.DomEvent.stopPropagation(e);
-        this.intendedFunction(this.pressed);
+    switchButtons: function() {
         if (this.pressed) {
             this.pressed = false;
             this.iconStart.setAttribute('class', 'fa fa-pause');
@@ -29,18 +27,48 @@ L.Control.AutoUpdate = L.Control.extend({
         }
     },
 
+    cbClick: function (e) {
+        L.DomEvent.stopPropagation(e);
+        this.intendedFunction(this.pressed);
+        this.switchButtons();
+    },
+
     intendedFunction: function() {
         alert('no function selected');
     },
 
     stopUpdate: function() {
-        this.socket.close();
+        if (this.socket) {
+            this.socket.close();
+            this.socket = null;
+        }
     },
 
     autoUpdate: function() {
         var me = this;
         this.socket = new WebSocket('ws://' + window.location.host + '/ws');
 
+        this.socket.onerror = function(evt) {
+            me.stopUpdate();
+            me.switchButtons();
+        };
+
+        this.socket.onclose = this.socket.onerror;
+
+        this.socket.onopen = function(evt) {
+            // Sending pings every 5 secs to keep connection alive.
+            var heartbeat = function() {
+                if (heartbeat && me.socket) {
+                    me.socket.send("PING");
+                    setTimeout(heartbeat, 8000);
+                } else {
+                    // Prevent sending pings to re-opened sockets.
+                    heartbeat = null;
+                }
+            };
+            setTimeout(heartbeat, 8000);
+        };
+
         this.socket.onmessage = function(evt) {
 
             var updatePlayers = function(json) {