> About multiple hostnames: we could have that in the (CacheManager) layer
> on top of the caching proxy implementations. The CacheManager would just
> call the |purge($url)| multiple times with absolute URLs. This has the
> advantage of keeping the Varnish class cleaner.

so people do not retrieve the varnish service to ban/purge/refresh but a CacheManager service? does that implement the same interfaces as the Varnish service?