protected function getXML()
    {
        $key = 'xml_' . md5($this->url); // Everybody loves md5!

        if ($this->cache->has($key)) {
            $this->xml = $this->cache->get($key);
        } else {
            $this->xml = $this->fetchXML();

            $this->xml = $this->changeLinkElements($this->xml);

            $this->cache->put($key, $this->xml, $this->cacheTime);
        }
    }