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BitTorrent Chat Demystified 71

Posted by timothy
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."
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BitTorrent Chat Demystified

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  • ICQ (Score:4, Interesting)

    by Bodero (136806) on Thursday June 30, 2011 @07:24PM (#36629106)

    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!").

    • 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.

    • by errandum (2014454)

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

      • Erm Skype does use central servers for coordination.

        • Re:ICQ (Score:4, Informative)

          by errandum (2014454) on Thursday June 30, 2011 @08:36PM (#36629604)

          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 [mjalali.com]

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

          • There are also super nodes that Skype runs. If a client doesn't know any peers they connect to a known supernode.

            • by xnpu (963139)

              Not just that, depending on your firewall situation your chats will use the supernode as well.

            • by errandum (2014454)

              supernodes are not run by skype, they are user's computers that satisfy some conditions (not behind a firewall, decent computer/connection). It's all peer to peer.

    • Or they proved that you suffer from hallucinations.
    • Bolo an old tank game used ring communication it was very effective as long as everyone was close one idiot with a long ping could bring the game to a hault.
      • That line was a bit difficult to read until I realized that you glued two sentences together it is not a very good idea to do that you know?

  • by jmitchel!jmitchel.co (254506) on Thursday June 30, 2011 @07:25PM (#36629118)
    Magnet links, how do they work?
  • by hchesley (2327336) on Thursday June 30, 2011 @07:28PM (#36629142)
    Reference: Harry R. Chesley, "Asynchronous Background Networking on the Macintosh," Develop 5, Winter 1991. It was called Rumor Monger.
    • Re: (Score:3, Informative)

      by hchesley (2327336)
      • We are really good at reinventing the wheel. :)

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

        • by hitmark (640295)

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

          • by hchesley (2327336)
            Implementation detail. The algorithm used in 1991 could have been implemented over TCP/IP, except for initial discovery, which is not hard to solve. My point was in response to the question in this posting that seemed to imply that decentralized chat might not be possible. There's no question it's possible, as demonstrated in my system long ago. That's not to take away from the value of Williams' implementation, which is built on today's infrastructure and is probably very useful. And anyway, I love decen
          • by drb226 (1938360)
            Playing the good ol' "regurgitate what they said but slightly differently" trick:
            Difference is that the theorized tech is limited to a single planet. The new new stuff got a potential universal reach.
  • by errandum (2014454) on Thursday June 30, 2011 @07:46PM (#36629274)

    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.

    • by Korin43 (881732)

      This was academic work, kind of a proof of concept. Why would this be news in this day and age baffles me.

      Because no one cares about academic work. This is interesting because people can actually use it.

      • by errandum (2014454)

        you're not getting my point :)

        this was common and part of a course project for everyone there.

        it would be usable and it actually is a (very) simple version of how the Gnutella network worked which, if I remember correctly, allowed a very minimalist chat.

        also, skype is 99.999% p2p and it has been around for years (although it is a bit more advanced that this scheme).

        meh, for anyone that studied this in any degree there is nothing that astonishing in what has been done. Hurray, uTorrent has a chat client that

        • by Fnord666 (889225)

          this was common and part of a course project for everyone there.

          This might be useful information considering the website says that this is "patent pending". This could well be prior art. I haven't looked at the patent application yet though.

  • Can you? (Score:5, Informative)

    by JackSpratts (660957) on Thursday June 30, 2011 @07:52PM (#36629326) Homepage
    Yes, and it's called WASTE. Came out in '03 and I've been "running" a decentralized mesh non-stop ever since.
    • by Phizzle (1109923)
      Freaking awesome, thanks!
    • Re: (Score:2, Informative)

      by Anonymous Coward

      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.

  • IRC (Score:5, Funny)

    by wcoenen (1274706) <wcoenen@gmail.com> on Thursday June 30, 2011 @08:24PM (#36629520)
    Good old IRC isn't centralized either! http://en.wikipedia.org/wiki/Netsplit [wikipedia.org]
  • Is the chat encrypted?
    • by Anonymous Coward

      WASTE is encrypted and decentralized.

  • Magnet links? (Score:2, Interesting)

    by SkOink (212592)

    I must be a bit confused about how exactly a magnet link works. In order for me to access the magnet stream for a file I wanted to download, I would need a magnet link pointing to somebody who was serving the file, right?

    What happens when the person who the magnet link references turns off their computer? If the magnet link needs to "check in" and update itself on a regular basis to prevent against this, what makes it functionally different than hosting a .torrent?

    • by Anonymous Coward
      That's not at all how they work. magnet: URIs [wikimedia.org] (usually) only contain a description of the file to download, not where to find it. The description includes a hash so it can be found on a p2p network.
  • by burris (122191) on Thursday June 30, 2011 @10:04PM (#36630010)

    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.

    • by burris (122191)

      I forgot to mention that I think the Azureus/Vuze DHT and clients, which isn't compatible with the DHT that all other clients use, have had this type of chat feature for a long time. I think they create a chat room for each torrent, so you can chat with other people downloading what you are downloading.

  • Bonjour is multicast decentralized chatting.

    http://cspace.in/ [cspace.in]

    cspace is basically what OP is speaking about.

  • by cshark (673578) on Thursday June 30, 2011 @10:35PM (#36630162)

    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.

    • The Flash meshing is genuinely impressive. It's a very real implementation and it looks like it really works. The full implementation will be available in 11 - I'm honestly looking forward to it.

  • by Anonymous Coward

    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

    • by ewanm89 (1052822)
      ARPANET, hell, how you think the POTS works? Or even old telegraph cables. The difference is whether packet switched, broadcast or circuit switched.
      • by ewanm89 (1052822)
        I think if I chuck text files to each other over freenet, I probably have elementary distributed chat.
  • Yes, the old UNIX chat command didn't need a central server, every system was a client and a server. Nothing magic about expanding this with DHTs to make connecting easier.
  • When launching uChat :

    " uChat is requesting access to :

    ability to run in the background
    read access to all torrents
    write access to all torrents

    Would you grant this app access ?"

    NO, si i cant test it.

  • ...and apparently fairly old and easy to implement. Its a shame that those elite hackers at LULZSec didn't consider using it.

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