var keepAliveCounter = 0;
var keepAliveId;
var keepAliveURL;
var maxCounter;
var intervalPeriod;

function startKeepAlive(url, counter, interval) {
   keepAliveURL = url;
   maxCounter = counter;
   intervalPeriod = interval;
   keepAliveId = setInterval("keepAlive()", intervalPeriod);
}

function keepAlive() {
   keepAliveCounter++;
   if (keepAliveCounter > maxCounter) {
      clearAliveInterval();
      return;
   }

   AjaxRequest.get(
      {
         'url' : keepAliveURL,
         'onSuccess' : function(req) {}
      });
}

function clearAliveInterval() {
   if (keepAliveId) {
      clearInterval(keepAliveId);
   }

   return true;
}