var req;

window.setInterval("checkSession();", 60000)

function checkSession() {
	req = false;
    // branch for native XMLHttpRequest object
    if(window.XMLHttpRequest && !(window.ActiveXObject)) {
    	try {
			req = new XMLHttpRequest();
        } catch(e) {
			req = false;
        }
    // branch for IE/Windows ActiveX version
    } else if(window.ActiveXObject) {
       	try {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
      	} catch(e) {
        	try {
          		req = new ActiveXObject("Microsoft.XMLHTTP");
        	} catch(e) {
          		req = false;
        	}
		}
    }
	if(req) {
		req.onreadystatechange = processReqChange;
		req.open("POST", "ajax.asp?method=sessionCheck", true);
		req.send("");
	}
}

function processReqChange() {
    // only if req shows "loaded"
    if (req.readyState == 4) {
        // only if "OK"
        if (req.status == 200) {
            // ...processing statements go here...
            if (req.responseText=="multiLogin") {
	            window.location.replace("login.asp?method=logout&reason=multi");
            } else if (req.responseText=="forceLogout") {
	            window.location.replace("login.asp?method=logout");
            }
        } else {
            //alert("There was a problem retrieving the XML data:\n" + req.statusText);
        }
    }
}