The HUGE thing look complicate for no reason. The risk of making an error on dups files is close to impossible (1 / Billions * Billions) with an 160bits hash and filesize check. You simply do the download and check that the receive file match the hash...

And it's quite simple to code a component that can download from mutliple sources (swarm). You simply test the servers for resume capability, split the files to download in blocks, and create threads that request theses blocks on differents server, you can even create mutliple threads (connections) per server.

In order to improve download/connection speed each client should have a list of other client that have the same file and reply not only with there IP but with the IP of others that can provide the same file. This could be done if Hub (supernodes) are inserted in the network. They could scan for dups files!

I already have program a swarm component in Delphi and it's working well. I will now work on it to add on the fly add/remove of new download sources.

If any one want to work on it to let me know i will send you the sources. It's use Indy for TCP access.

Marc.
marc@szs.ca