public function dispatch($exception = null)
{
if ($exception) {
$message = $exception->getMessage();
} else {
$message = '';
}
$action = Common::getRequestVar('action', 'welcome', 'string');
if ($this->isAllowedAction($action)) {
echo FrontController::getInstance()->dispatch('Installation', $action, array($message));
} else {
Piwik::exitWithErrorMessage($this->getMessageToInviteUserToInstallPiwik($message));
}
exit;
}