public function connect()
    {
        $dsn = "sqlite:{$this->_file}";
        try {
            $class = $this->_handlerClass;
            $this->_handler = new $class($dsn);
            $this->_handler->setAttribute(
                PDO::ATTR_ERRMODE,
                PDO::ERRMODE_EXCEPTION
            );
            $this->_connected = true;
        } catch (\Exception $exp) {
            throw new ServiceException(
                "An error occurred when trying to connect to database " .
                "service. Error: {$exp->getMessage()}"
            );
        }
        return $this;
    }