Revolutionary Peer

By Steve Gillmor  |  Posted 2003-12-14 Print this article Print

-to-Peer Program Could Solve Problem"> One such candidate is peer-to-peer, as resurrected in the form of Bram Cohens BitTorrent. Its an elegant protocol for distributing files, one that takes advantage of "the unused upload capacity of your customers." BitTorrent breaks up files into shards that are uploaded around the network as the file is downloaded by multiple clients. The more popular a file, the more endpoints exist. You download a file with BitTorrent by simultaneously collecting shards, assembling them together locally as they arrive. Map this to RSS feeds: the more popular the feed, the more nodes on the network serving pieces of the feed. That would allow rapid downloads by many users by distributing the data across multiple sites. Its a digital Robin Hood, redistributing the wealth from the server to a network of peers. BitTorrent does cryptographic hashing of all data, so feed owners can be confident the file reaches its target unchanged.
But theres even more to this disruptive alliance: a small amount of special code known as a tracker sits inside the host Web site and emits information to help other downloaders find each other. As Bram Cohen describes: "[Trackers] speak a very simple protocol layered on top of HTTP in which a downloader sends information about what file its downloading, what port its listening on, and similar information, and the tracker responds with a list of contact information for peers which are downloading the same file."
So youve got a list of peers connected via known ports, a trusted group of RSS feed subscribers, who can marshall their resources for additional economic benefit. That could take the form of an affinity group marketing their attention to an advertiser or political cause, a secure pool of computing resources for distributing confidential information, and a pathway for signaling information about new content on that particular subnetwork. Even if none of this were to be leveraged, the combined polling of the group, if staggered by one minute intervals, would monitor a feed even though each client only polled once per hour. But once you were on the BitTorrent feed, you could shut off the polling after the first connection. Next page: Two great disruptive technologies that taste great together.

Steve Gillmor is editor of's Messaging & Collaboration Center. As a principal reviewer at Byte magazine, Gillmor covered areas including Visual Basic, NT open systems, Lotus Notes and other collaborative software systems. After stints as a contributing editor at InformationWeek Labs, editor in chief at Enterprise Development Magazine, editor in chief and editorial director at XML and Java Pro Magazines, he joined InfoWorld as test center director and columnist.

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