function GetXmlHttpObject(handler)
        { 
            var objXmlHttp=null

            if (navigator.userAgent.indexOf("Opera")>=0)
            {
                alert("This example doesn't work in Opera") 
                return 
            }
            if (navigator.userAgent.indexOf("MSIE")>=0)
            { 
                var strName="Msxml2.XMLHTTP"
                if (navigator.appVersion.indexOf("MSIE 5.5")>=0)
                {
                    strName="Microsoft.XMLHTTP"
                } 
                try
                { 
                    objXmlHttp=new ActiveXObject(strName)
                    objXmlHttp.onreadystatechange=handler 
                    return objXmlHttp
                } 
                catch(e)
                { 
                    alert("Error. Scripting for ActiveX might be disabled") 
                    return 
                } 
            } 
            if (navigator.userAgent.indexOf("Mozilla")>=0)
            {
                objXmlHttp=new XMLHttpRequest()
                objXmlHttp.onload=handler
                objXmlHttp.onerror=handler 
                return objXmlHttp
            }
        }