Got so into blogging the "how" in the last post that I forgot about the "why", although I hope that's fairly obvious.
The W3C puts it like this:
The partial GET method is intended to reduce unnecessary network usage
A server MAY ignore the Range header. However, HTTP/1.1 origin servers and intermediate caches ought to support byte ranges when possible, since Range supports efficient recovery from partially failed transfers, and supports efficient partial retrieval of large entities.
- Keep the Internet clean (hear that, spammers?)
- Speed up client requests.
I'm sure I had a point, but it's gone. The thought of all the crap floating around in the ether has depressed me too much to think. I think I need to see Marvin to cheer me up.
BTW our web hosting company honours ranges so perhaps it's not all that bad.