private function resolveBaseUriVar() {
        $envName = 'APP_BASE_URI';
        $envValue = null;

        if (!isset($_SERVER[$envName]))
            $envName = 'REDIRECT_'.$envName;

        while (isset($_SERVER[$envName])) {
            $envValue = $_SERVER[$envName];
            $envName = 'REDIRECT_'.$envName;
        }
        return $envValue;
    }