private function setupHandlers($handlers)
    {
        $this->handlers = array();
        foreach ($handlers as $handlerClass => $handlerDetails) {
            $options = array();
            if (isset($handlerDetails[Config::KEY_OPTIONS])) {
                $options = (array)$handlerDetails[Config::KEY_OPTIONS];
            }

            if (isset($handlerDetails[Config::KEY_CLASS])) {
                $handlerClass = $handlerDetails[Config::KEY_CLASS];
            }

            if (!class_exists($handlerClass)) {
                throw new Exception(
                    'Cannot instantiate instance of '.$handlerClass
                );
            }
            $this->handlers[] = new $handlerClass($options);
        }
    }