var xmlHttp = null;
/** Creates a HTTP request object. */
function createXMLHttpRequest() {

    if (window.XMLHttpRequest) {
        try {
            xmlHttp = new XMLHttpRequest();
        } catch(e) {
            xmlHttp = null;
        }
    } else if (window.ActiveXObject) {
       	try {
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
      	} catch(e) {
            try {
                xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            } catch(e) {
                xmlHttp = null;
            }
        }
    }
}