function isNull(obj) { 
	if (typeof(obj) == "undefined")
	  return true;
	if (obj == undefined)
	  return true;
	if (obj == null)
	  return true;
	if (obj == "")
	  return true;
	return false;
}
function isFileOverdue(siteRootUrl) {
	var time = document.lastModified;
	var htmlurl = window.location.href;
 	var result = httpRequest("get",null,siteRootUrl+"/console/htmlengine/autohtmlengine_ajax.aspx?type=isfileoverdue&time="+time+"&htmlurl="+htmlurl+"&temp=" + new Date().getTime());
	if(!isNull(result)) {  
		window.location.href=result;  
	} 
}