protected function renderInputForm() {
    $parameters = $this->getInputParameters();
    if (count($parameters)) {
      printf('<h2>Enter %s parameters</h2>', $this->getName());
      print '<form method="POST"><fieldset>';
      foreach ($parameters as $parameter) {
        $name = $parameter['name'];
        $display = $parameter['display'];
        $currentValue = isset($_POST[$name]) ? $_POST[$name] : '';
        printf('%s: <input name="%s" value="%s">', $display, $name,
            $currentValue);
        if ($parameter['required']) {
          print '*';
        }
        print '</br>';
      }
      print '</fieldset>*required<br/>';
      print '<input type="submit" name="submit" value="Submit"/>';
      print '</form>';
    }
  }