function doRequestUsingPost(aff)
{
         var Xml_Http_Request=CreateReqeust();
         var url="XZG_Servlet/WriteXml?timeStamp=" + new Date().getTime();
         var queryString=createQueryString(aff);
         Xml_Http_Request.open("POST",url,true);
         Xml_Http_Request.onreadystatechange=function()
         {
                 if(Xml_Http_Request.readyState==4)
                 {
                            if(Xml_Http_Request.status==200)
                            {
                                    parseResults();
                            }
                 }
         }
         Xml_Http_Request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
         Xml_Http_Request.send(queryString);
}

function createQueryString(LayerInfo)
{    
         var queryString = "LayerInfo=" + LayerInfo;
         return queryString;
}