Added "heartbeat" for update throttling.

guacamole/client/web/WEB-INF/web.xml

@@ -61,6 +61,15 @@
         <servlet-name>Clipboard</servlet-name>
         <url-pattern>/clipboard</url-pattern>
     </servlet-mapping>
+    <servlet>
+        <description>Client "ready-to-receive" heartbeat</description>
+        <servlet-name>Ready</servlet-name>
+        <servlet-class>net.sourceforge.guacamole.net.input.Ready</servlet-class>
+    </servlet>
+    <servlet-mapping>
+        <servlet-name>Ready</servlet-name>
+        <url-pattern>/ready</url-pattern>
+    </servlet-mapping>
     <servlet>
         <description>Key input servlet.</description>
         <servlet-name>Key</servlet-name>

guacamole/client/web/javascript/guacamole.js

@@ -540,7 +540,27 @@ function VNCClient(display) {
             handler(parameters);
 
     }
-        
+
+
+    function sendReady() {
+
+        // Start heartbeat signal
+        var heartbeat = new XMLHttpRequest();
+        heartbeat.open("GET", "ready");
+
+        heartbeat.onreadystatechange = function() {
+
+            if (heartbeat != null && heartbeat.readyState >= 2) {
+                heartbeat = null;
+                setTimeout(sendReady, 50);
+            }
+
+        };
+
+        heartbeat.send();
+
+    }
+
 
     this.connect = function() {
 
@@ -555,6 +575,7 @@ function VNCClient(display) {
         var message = new GuacamoleMessage(connect_xmlhttprequest.responseXML);
         if (!message.hasErrors()) {
             setState(STATE_WAITING);
+            sendReady();
             handleResponse(makeRequest()); // Start stream if connection successful
         }
         else