function login()
{
    xmlHttpLogin = GetXmlHttpObject();
    if (xmlHttpLogin == null)
    {
        alert (NO_AJAX_SUPPORT_MESSAGE);
        return;
    }
    var url = "process-login.php" + "?rand=" + Math.random();
    var user_name = document.getElementById('user_name');
    var password = document.getElementById('password');
    if(user_name.value != "" && password.value != "")
    {
        url = url + "&user_name=" + user_name.value + "&password=" + password.value;
    }
    xmlHttpLogin.onreadystatechange = stateChangedLogin;
    xmlHttpLogin.open("GET",url,true);
    xmlHttpLogin.send(null);
}

function stateChangedLogin()
{
    document.getElementById("login_message").innerHTML = "Signing In...";
    document.getElementById("login_message").style.visibility = "visible";
    if (xmlHttpLogin.readyState == 4 || xmlHttpLogin.readyState == "complete")
    {
        var xmlDoc = xmlHttpLogin.responseXML.documentElement;
        var message = getField(xmlDoc.getElementsByTagName("message")[0]);
        var success = getField(xmlDoc.getElementsByTagName("success")[0]);

        if (message == "Login Successful")
        {
            location.reload(true);
        }
        else
        {
            document.getElementById("login").style.height = "170px";
            document.getElementById("login_message").innerHTML = message + "!<br><input type=\"submit\" id=\"submitForm\" value=\"Sign In Again\">";
        }
    }
}