include "SSOclient.php";
  $sso = new SSOclient($data, $sign, $REMOTE_ADDR, "targetname");
  if ($sso->oklogin()){
    echo "You are logged in as ", $sso->loginvalues["username"];
    // create a session here
  } else {
    echo "error: ", $sso->reason();
    // perhaps a link to another try?
  }