The brainstorm Bram Cohen had about sharing large files over the Internet makes even the usual February cloudbursts and tempests outside his Bellevue, Wa. residence seem fairly tame in comparison.
Since it burst on the scene two short years ago, BitTorrent has done for file sharing (much of it the legal variety, by the way) what hypermedia did for information sharing, applying the power-of-the-network to share the load (or the download in this case) among multitudes of users.
The essential idea is a one-file-from-many distribution scheme, where a large media file (like a movie) is chunked into many smaller, more manageable packets and simultaneously distributed en masse. Indeed, the theory has been so successful in reaching a critical mass that BitTorrent has touched off a downpouring of downloading that some estimate can amount to 1/3rd of all Internet traffic at a given point in time. And since the disintegrated and re-integrated files can often be unlicensed and unauthorized, the program has also touched off a firestorm of protest among motion picture producers who see BitTorrent as the nefarious Napster of the video domain.
| The secret to BitTorrent is collaboration. Every user trying to download a file also participates in sharing the file with other users. Instead of the traditional client and server relationship in which multiple clients request a file from a single server, every client in a BitTorrent system is also a server. First, each file is divided into smaller pieces that can be freely distributed by peers before being assembled again into the complete file.
To speed downloads, BitTorrent also uses an ingenious, if slightly counterintuitive, principle in selecting which piece of a file to request from another peer. The software scans all the available pieces from the connected peers and selects the scarcest piece in the swarm. If all peers simply downloaded pieces in order, the swarm would quickly accumulate an unnecessarily large supply of initial pieces and a much smaller supply of later ones. BitTorrent’s approach, called rarest first, creates a more even distribution of available pieces. If a given piece is in short supply, peers will start downloading it more often, thereby creating more available copies. The BitTorrent software is also designed to bring cooperative peers together. If you have a track record of uploading information, and not just sucking down data from other peers without returning the favor, the software will automatically connect to other, equally magnanimous users, allowing you to download files faster. Cohen calls this “leech resistance.” |
Retaliating against BitStormers by adopting similar tactics to their industry brethren in the music world, the Motion Picture Association of America began a legal onslaught against some BitTorrent users last year. Specifically, the nemeses are those who use their computer servers to host BitTorrent files. Still, the number of participants is so “tipping point” large, the BitTorrent universe seems somehow unphased.
Bram moved to Bellevue in 2003 to go to work for Valve Software, makers of the Half-Life 2″ Video Game. His asignment was related to developing Valve’s online software-distribution engine, called Steam, which he quickly ran out of after just a few months. An independent spirit in the highly networked Web info-society, Bram has opted to support his wife and two children with the revenue he is able to generate form BitStream donations and a limited amount of advertising on his Website.
Lately, he appears to be conjuring what could be a more commercial venture out of his pro bono enterprise, working with developers in San Francisco and Helsinki, Finland, to prepare new feature-packed BitTorrent versions. But the bit is out of the bag, so to speak. He’ll have competition for his own invention from other firms who have already piggybacked the BitTorrent idea for their own products.
Cohen considers Hollywood a slumbering and lumbering giant that could be profiting if it were more nimble about distributing content to its legions of fans, but, instead, is simply being outmaneuvered by impatient consumers who take to sharing their homemade media files online. “A lot of Hollywood’s problem is they don’t want to make stuff available,” Cohen remarked. “If you don’t let people buy your stuff, there’s no way they can pay you for it.”
Surpisingly, Bram’s hobbies do not include a zeal for the same TV, movie and musical fare as those who use BitTorrent to share the latest episodes. Rather, he is a lifelong puzzle-fiend who has collected dozens of different 3-D brain teasers that he enjoys solving in rapid succession. Cohen also happens to be a skilled juggler who can coordinate up to five lead balls shooting into the air at a time, so of like the way that TCP/IP handles packets of information.
The newfangled northwesterner grew up back east in the concrete canyons of Manhattan’s Upper West Side, where his father taught him how to write programming code when most kids were learning to ride a bicycle. By age 10, he was doing real-world coding without training wheels. Not one to suffer long through the drudgery of classrooms and textbooks, Bram attended the State University of New York at Buffalo but left after two years. In 2002, he co-founded an annual hacker conference called CodeCon. Cohen suffers from a form of autism that is marked by an obsession with complex topics, such as puzzling patterns, and software, of course.
BitTorrent has taken the world by storm since it was first unveiled at CodeCon in 2002. It will be interesting to see what brainstorm’s Puget Sound’s filesharing rainmaker has in store for the next four years. [24×7]
Bram Cohen watches the BitTorrent storm clouds form under the murky skies of the Puget Sound
