The Blizzard updater is actually a very cool download utility, worth hacking/poking at.
AFAIK it pioneered the concept of "web seeds", using HTTP GETs with a Range: header to download specific chunks from a CDN that were not healthy/available in the swarm.
AFAIK it pioneered the concept of "web seeds", using HTTP GETs with a Range: header to download specific chunks from a CDN that were not healthy/available in the swarm.