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BitTorrent Chat Demystified

Posted by timothy on from the like-chat-roulette-but-different dept.

An anonymous reader writes "Can you really do group chat with no central server? BitTorrent's Patrick Williams has developed a new app that leverages a distributed architecture to eliminate the need for any servers — even to host a buddy list. He says magnet links are the key."

20 of 71 comments (clear)

  1. ICQ by Bodero · · Score: 3, Interesting

    Can you really do group chat with no central server?

    ICQ proved that it was possible over a decade ago. Simultaneously, they proved that it was not a good idea (as I remember friends saying, "Who are you talking to? I don't see him! Re-invite!").

    1. Re:ICQ by igreaterthanu · · Score: 2

      Simultaneously, they proved that it was not a good idea (as I remember friends saying, "Who are you talking to? I don't see him! Re-invite!")

      That's an implementation issue, it's quite possible to write p2p chat software at least as good as existing centralized chat software.

      --
      I dream of a nation where a man is not judged by his skin color but by an number assigned by a credit rating agency.
    2. Re:ICQ by errandum · · Score: 2

      Skype is p2p and while you might not see someone right after you connect it usually ends up showing everyone and is reliable enough.

    3. Re:ICQ by larry+bagina · · Score: 2

      Or they proved that you suffer from hallucinations.

      --
      Do you even lift?

      These aren't the 'roids you're looking for.

    4. Re:ICQ by cheater512 · · Score: 2

      Erm Skype does use central servers for coordination.

    5. Re:ICQ by errandum · · Score: 3, Informative

      I believe the only central server is for authentication (as it should be). It might also save the "initial" budy list, but a local copy is also kept.

      Or actually, 1 minute in google:

      http://www.mjalali.com/blog/?p=10

      "Skype Authentication Server: This is the only centralized Skype server which is used to authenticate Skype users. "

  2. Magnet links by jmitchel!jmitchel.co · · Score: 4, Funny

    Magnet links, how do they work?

  3. I did it at Apple in 1991 by hchesley · · Score: 5, Informative

    Reference: Harry R. Chesley, "Asynchronous Background Networking on the Macintosh," Develop 5, Winter 1991. It was called Rumor Monger.

    1. Re:I did it at Apple in 1991 by hchesley · · Score: 3, Informative

      Online copy of the article: http://www.mactech.com/articles/develop/issue_05/6-30_Chesley_Docv9_CHG.html.

    2. Re:I did it at Apple in 1991 by elsurexiste · · Score: 2

      We are really good at reinventing the wheel. :)

      "If you don't learn from the past, it'll repeat itself", or something like that.

      --
      I rarely respond to comments. Also, don't ask for clarifications: a brain and Google are faster, believe me!
    3. Re:I did it at Apple in 1991 by hitmark · · Score: 2

      Difference is that the mentioned tech was limited to a single appletalk network. The new stuff got a potential global reach.

      --
      comment first, facts later. http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm
  4. Actually... by errandum · · Score: 2

    I implemented something like this once, a long time ago, on a small scale. Just use sequence numbers to determine order, it might not be perfect, but it worked. Each client held a hash table with a limit size (can't remember) of the people they could "see". If you couldn't find a target you'd just "multicast" it to all the ones you knew were there and ask them to deliver, with a limited number of hops (to avoid infinite cycles).

    The initial connection relied on invites. This was academic work, kind of a proof of concept. Why would this be news in this day and age baffles me.

  5. Can you? by JackSpratts · · Score: 5, Informative

    Yes, and it's called WASTE. Came out in '03 and I've been "running" a decentralized mesh non-stop ever since.

    1. Re:Can you? by Luckyo · · Score: 2

      That's what many people sharing on local uni networks started to use after DC++ hubs started to get closed. Funny thing is, while much harder to lock down, WASTE network utterly rapes local bandwidth. So closing DC++ hubs typically turned out a major pain for support, who instead of seeing decrease in internal traffic, saw a very sharp increase.

    2. Re:Can you? by Anonymous Coward · · Score: 2, Informative

      This has been possible for a long time.
      Some applications that can do this apart from WASTE are:
      - Oneswarm
      - Retroshare
      - GNUnet
      - Torchat
      All decentralized, and apart from torchat they are all activity being developed.

  6. IRC by wcoenen · · Score: 5, Funny

    Good old IRC isn't centralized either! http://en.wikipedia.org/wiki/Netsplit

    1. Re:IRC by Rizimar · · Score: 2

      Good old IRC isn't centralized either! http://en.wikipedia.org/wiki/Dalnet

      Fix'd.

  7. It uses the DHT by burris · · Score: 2

    The BitTorrent DHT is a giant distributed database formed among most of the BT clients that maps ip addresses / port numbers to arbitrary keys. That's how the clients talking in the same room find each other.

  8. Nice. by cshark · · Score: 2

    Totally decentralized chat! Awesome! We've needed this for a very long time, and I don't know why it's taken so long to put together. Not that I'm complaining. Soon as there's a Flash applet that'll handle the protocol, we're in business. I hope this is widely adopted.

    --

    This signature has Super Cow Powers

  9. Am I the first ham in the room? APRS was earlier! by Anonymous Coward · · Score: 2, Interesting

    Okay, it's not the same thing at all (just like most of the other things people are suggesting were first/earlier), but it is decentralized chat with radios, since 1992.

    Look it up, even if you're not a ham, it's pretty cool stuff.

    73 de AB9UL