public function executeCommand($command, array $parameters = array())
    {
        $content = $this->post(
            sprintf('http://%s:%d/_s_/dyn/Driver_%s', $this->host, $this->port, $command),
            array_merge($parameters, array('sahisid' => $this->sid))
        )->getContent();

        if (false !== strpos($content, 'SAHI_ERROR')) {
            throw new Exception\ConnectionException('Sahi proxy error. Full response:' . PHP_EOL . $content);
        }

        return $content;
    }