Thursday, November 23, 2006

Is Bittorrent really just an old tech in new box ?

Google has become a great friend to every one, it's always there when people get so bored that they could not think of anything else to do. Googling sometime points me to unexpected, pleasantly interesting article. Can't remember what brought me to this one, but i remember bookmarking it right away.

That article is from a creator of Limewire, with comments about Bittorrent. Limewire was the most successfull and most widely-used p2p client that implements the Gnutella protocol. Bittorrent refers to both the protocols and the "mainline" client, created by Bram Cohen sometime in 2002. Before 2005, Limewire was still ahead of Bittorrent in the popularity contest (number of users); but Bittorrent had quickly turned things around. It is now believed to be the most popular p2p client, leaving the second-place clients far, far behind.

Coming back to the article, the author claims that Bittorrent uses their innovative swarm-downloading technique and works better just because it "did less" and is better packaged. I agreed that other publications should not have praised Bittorrent because of its innovative swarm downloading. However, Bittorrent's success is made of many different things; mainly its pieces selection and peer selection algorithm. They contribute greatly to the robustness and high performance of the protocol. Only the swarm downloading "idea" is used, the actual deployment is quite different from Limewire. In Limewire, a peer can concurrently swarm-download from many seeds/sources. A peer bittorrent, on the other hand, concurrently downloads block from other downloading-peers who have not yet had a complete copy of the file. Futhermore, free riders (which i belive still remains a headeach for Gnutella as well as Limewire) are discouraged by implementing variation of tit-for-tat startegy for the peer selection algorithm.

After all, these unique features of Bittorrent should not be viewed as "new box". They are much more than that.

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