public function service(ServletRequestInterface $servletRequest, ServletResponseInterface $servletResponse)
    {

        // pre-initialize the X-POWERED-BY header
        $poweredBy = $this->getPoweredBy();

        // append an existing X-POWERED-BY header if available
        if ($servletResponse->hasHeader(HttpProtocol::HEADER_X_POWERED_BY)) {
            $poweredBy = $servletResponse->getHeader(HttpProtocol::HEADER_X_POWERED_BY) . ', ' . $poweredBy;
        }

        // set the X-POWERED-BY header
        $servletResponse->addHeader(HttpProtocol::HEADER_X_POWERED_BY, $poweredBy);

        // servlet path === relative path to the template name
        $template = $servletRequest->getServletPath();

        // check if the template is available
        if (!file_exists($pathToTemplate = $this->getWebappPath() . $template)) {
            if (!file_exists($pathToTemplate = $this->getAppBase() . $template)) {
                if (!file_exists($pathToTemplate = $this->getBaseDirectory() . $template)) {
                    throw new ServletException(sprintf('Can\'t load requested template \'%s\'', $template));
                }
            }
        }

        // process the template
        ob_start();
        require $pathToTemplate;

        // add the servlet name to the response
        $servletResponse->appendBodyStream(ob_get_clean());
    }