protected function read(Mapper\Map $map, $identifier)
    {
        $url = $this->buildUri($map->getRemoteName() . '/' . $identifier);
        if (!file_exists($url) || !is_file($url)) {
            return;
        }
        $data = file_get_contents($url, false, $this->context ? : null);
        return $this->descriptor->unserialize($map, $data);
    }
protected function read(Mapper\Map $map, $identifier)
    {
        $url = $this->buildUri($map->getRemoteName() . '/' . $identifier);
        if (!file_exists($url) || !is_file($url)) {
            return;
        }
        $data = file_get_contents($url, false, $this->context ? : null);
        return $this->descriptor->unserialize($map, $data);
    }
@param Mapper\Map $map
@param            $identifier

@return mixed