Each account can send a string with extra information to GeoScaling using an [[wp>XML-RPC]] call. This extra string can then be accessed from smart subdomain scripts through the $extra_info variable. The string can be mostly anything.

To send the extra information you need to call the function named //geoscaling.extra_info//. The URL of our XML-RPC server is http://api.geoscaling.com/dns2/xml-rpc/. The function takes 3 arguments:

  * username - string - your username
  * password - string - your password
  * extra_info - string - the string with extra information that you want to send

In the example below we serialized a PHP array and sent it as the string. The code makes use of the [[http://phpxmlrpc.sourceforge.net/|XML-RPC for PHP]] library:

<code php>
<?PHP

include("lib/xmlrpc/xmlrpc.inc");

$client = new xmlrpc_client("http://api.geoscaling.com/dns2/xml-rpc/");
//$client->setdebug(1);

$timeout = 5;

$payload['datacenter1'] = "43";
$payload['datacenter2'] = "22";
$payload['datacenter3'] = "87";

$msg = new xmlrpcmsg("geoscaling.extra_info",
        array(
                php_xmlrpc_encode("USERNAME"),
                php_xmlrpc_encode("PASSWORD"),
                php_xmlrpc_encode(serialize($payload))
            )
        );

$response = $client->send($msg, $timeout);

if($response->faultCode())
{
    print_r($response->faultString());
}
else
{
    print_r(php_xmlrpc_decode($response->val));
}

echo "\n";

?>
</code>

The XML-RPC function returns one of the following values:

<code php>
define("OK", 1, true);
define("WRONG_PARAMETER_COUNT", 2, true);
define("USER_PASS_INCORRECT", 3, true);
define("EXTRA_INFO_NOT_STRING", 4, true);
define("EXTRA_INFO_TOO_LONG", 5, true);
</code>

The following is a user contribution of a combined, closest server + failover + take me offline during deployment.
- first the smart subdomain script
<code php>
/*
GeoScaling "smart subdomain script"
        PURPOSE:
        1/ associate url/IP with the physically closest server, monitoring with www.monitis.com reveals minimum of 2x improvement in latency if we do this
        2/ take a server out of the list of possible servers if GeoScaling monitoring shows it as down
        3/ take a sever out of the list (immediate effect) if we are about to deploy an upgrade of the app software by sending "extra_info"

        Contributed BY: keitht@sasimedia.net
        AVAILABLE INFRASTRUCTURE CONSULTING ON
        1/ automated build and deploy the N servers in the cloud
        2/ Unix or Windows cloud server setup (linode / Rackspace / other)
        3/ Techniques for achieving fastest initial page load
        4/ No SQL keystore for database replication across cloud servers (Hazelcast + Voldemort + Oracle BDB)
        5/ HA / 100 % uptime
        6/ Smart browser clients (Flex / GWT), with service calls automatically tied to the fastest responding server (not necessarily the closest)
*/

$info = unserialize($extra_info);

if($uptime['Linode-s1.info']==1 && strcmp($info['linode-s1-offline'],'true') != 0){
$new_server['lat'] = 37.4919627;
$new_server['lon'] = -121.93811;
$new_server['loc'] = "Fremont, California";
$new_server['ip'] = "1.1.1.1"; //linode-s1 CA
$servers[] = $new_server;
}

if($uptime['rackspace-s1.info']==1 && strcmp($info['rackspace-s1-offline'],'true') != 0){
$new_server['lat'] = 32.7833333;
$new_server['lon'] = -96.8;
$new_server['loc'] = "Dallas, TX";
$new_server['ip'] = "1.1.1.1"; //rackspace-s1 DALLAS
$servers[] = $new_server;
}

if($uptime['rackspace-s1.info']==1 && strcmp($info['rackspace-s2-offline'],'true') != 0){
$new_server['lat'] = 41.85;
$new_server['lon'] = -87.65;
$new_server['loc'] = "Chicago, IL";
$new_server['ip'] = "1.1.1.1";  // rackspace-s2 CHICAGO
$servers[] = $new_server;
}

if($uptime['Linode-s2.info']==1 && strcmp($info['linode-s2-offline'],'true') != 0){
$new_server['lat'] = 33.73;
$new_server['lon'] = -84.38;
$new_server['loc'] = "Atlanta, GA.";
$new_server['ip'] = "11.1.1.1";  // linode-s2 ATLANTA
$servers[] = $new_server;
}

$current_lat = $city_info['latitude'];
$current_lon = $city_info['longitude'];

$minimum_distance = PHP_INT_MAX;
$minimum_distance_server_id = 0;

for($i=0 ; $i<sizeof($servers); $i++)
{
    $server = $servers[$i];
    $distance_to_user = @distance($current_lat, $current_lon, $server['lat'], $server['lon'], "k");
    if($distance_to_user<$minimum_distance)
    {
	$minimum_distance = $distance_to_user;
	$minimum_distance_server_id = $i;
    }
}

$output[] = array("A", $servers[$minimum_distance_server_id]['ip']);

/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*::                                                                         :*/
/*::  this routine calculates the distance between two points (given the     :*/
/*::  latitude/longitude of those points). it is being used to calculate     :*/
/*::  the distance between two zip codes or postal codes using our           :*/
/*::  zipcodeworld(tm) and postalcodeworld(tm) products.                     :*/
/*::                                                                         :*/
/*::  definitions:                                                           :*/
/*::    south latitudes are negative, east longitudes are positive           :*/
/*::                                                                         :*/
/*::  passed to function:                                                    :*/
/*::    lat1, lon1 = latitude and longitude of point 1 (in decimal degrees)  :*/
/*::    lat2, lon2 = latitude and longitude of point 2 (in decimal degrees)  :*/
/*::    unit = the unit you desire for results                               :*/
/*::           where: 'm' is statute miles                                   :*/
/*::                  'k' is kilometers (default)                            :*/
/*::                  'n' is nautical miles                                  :*/
/*::  united states zip code/ canadian postal code databases with latitude & :*/
/*::  longitude are available at http://www.zipcodeworld.com                 :*/
/*::                                                                         :*/
/*::  For enquiries, please contact sales@zipcodeworld.com                   :*/
/*::                                                                         :*/
/*::  official web site: http://www.zipcodeworld.com                         :*/
/*::                                                                         :*/
/*::  hexa software development center © all rights reserved 2004            :*/
/*::                                                                         :*/
/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/

//echo distance(32.9697, -96.80322, 29.46786, -98.53506, "m") . " miles<br>";
//echo distance(32.9697, -96.80322, 29.46786, -98.53506, "k") . " kilometers<br>";
//echo distance(32.9697, -96.80322, 29.46786, -98.53506, "n") . " nautical miles<br>";


function distance($lat1, $lon1, $lat2, $lon2, $unit)
{

  $theta = $lon1 - $lon2;
  $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
  $dist = acos($dist);
  $dist = rad2deg($dist);
  $miles = $dist * 60 * 1.1515;
  $unit = strtoupper($unit);

  if ($unit == "K") {
    return ($miles * 1.609344);
  } else if ($unit == "N") {
      return ($miles * 0.8684);
    } else {
        return $miles;
      }
}
</code>

Here is the php script to send the extra info taking a selected server offline with the url like this 
http://localhost/offlineServerViaGeoScaling.php?server=linode-s2&offline=false
<code php>
<?PHP
/*
 GeoScaling "extra_info script"
        PURPOSE:
        1/ send extra_info to take a sever out of the list (immediate effect) if we are about to deploy an upgrade of the app software

        Contributed BY: keitht@sasimedia.net
        AVAILABLE INFRASTRUCTURE CONSULTING ON
        1/ automated build and deploy the N servers in the cloud
        2/ Unix or Windows cloud server setup (linode / Rackspace / other)
        3/ Techniques for achieving fastest initial page load
        4/ No SQL keystore for database replication across cloud servers (Hazelcast + Voldemort + Oracle BDB)
        5/ HA / 100 % uptime
        6/ Smart browser clients (Flex / GWT), with service calls automatically tied to the fastest responding server (not necessarily the closest)
 */
include("lib/xmlrpc.inc");

$client = new xmlrpc_client("http://api.geoscaling.com/dns2/xml-rpc/");
//$client->setdebug(1);

$timeout = 5;
echo  $_GET['server'] . '-offline'  . "=" .  $_GET['offline'] . "\n";


$payload[$_GET['server'] . '-offline'] = $_GET['offline'];

// set online any servers not specified in arguments
if ($_GET['server'] != 'linodes1')
    $payload['linode-s1-offline'] = 'false';

if ($_GET['server'] != 'yrs1')
    $payload['rackspace-s1-offline'] = 'false';

if ($_GET['server'] != 'yyyy-s2')
    $payload['rackspace-s2-offline'] = 'false';

if ($_GET['server'] != 'xxxx-s2')
    $payload['linode-s2-offline'] = 'false';


$msg = new xmlrpcmsg("geoscaling.extra_info",
        array(
                php_xmlrpc_encode("keith198"),
                php_xmlrpc_encode("daddy1"),
                php_xmlrpc_encode(serialize($payload))
            )
        );

$response = $client->send($msg, $timeout);

if($response->faultCode())
{
    print_r($response->faultString());
}
else
{
    print_r(php_xmlrpc_decode($response->val));
}

echo "\n";

?>
</code>

The following contributed code makes an XML-RPC call from Java. It uses the redstone XML-RPC library: http://xmlrpc.sourceforge.net/

<code java>
  // test geoscaling api via restlet
        String url="http://api.geoscaling.com/dns2/xml-rpc/";
        XmlRpcClient client = null;
        try {
            client = new XmlRpcClient(url,false);
            Object token = client.invoke( "geoscaling.extra_info", new Object[] { "USER", "PASS","s1-offline=true" } );
            int x = 1+2;
           } catch (MalformedURLException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        } catch (XmlRpcFault xmlRpcFault) {
            xmlRpcFault.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }
</code>