/* picturevote.php */
[...]
    // Ausführen des Tasks durch den Controller
    $controller = new picturevotecontroller();

    // Task ermitteln
    $task = JRequest::getWord('task');

    $controller->execute($task);

/* controller.php */
    class picturevotecontroller extends JController {
    /* Several Tasks */
        public function login() {
            JRequest::setVar('view', 'login');

            // Model bestimmen
            $model = $this->getModel('login');

            $model->login();
        }