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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."

50 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. "

    6. Re:ICQ by cheater512 · · Score: 1

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

    7. Re:ICQ by jimbolauski · · Score: 1

      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.

      --
      Knowledge = Power
      P= W/t
      t=Money
      Money = Work/Knowledge so the less you know the more you make
    8. Re:ICQ by xnpu · · Score: 1

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

    9. Re:ICQ by errandum · · Score: 1

      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.

    10. Re:ICQ by Drafell · · Score: 1

      If only I could mod this :-(

    11. Re:ICQ by DaVince21 · · Score: 1

      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?

      --
      I am not devoid of humor.
  2. Magnet links by jmitchel!jmitchel.co · · Score: 4, Funny

    Magnet links, how do they work?

    1. Re:Magnet links by Qzukk · · Score: 1

      Magnet links, how do they work?

      Lobsters

      --
      If I have been able to see further than others, it is because I bought a pair of binoculars.
    2. Re:Magnet links by mug+funky · · Score: 1

      i just threw up in my mouth. that's worse than goatse

    3. Re:Magnet links by Billly+Gates · · Score: 1

      "i just threw up in my mouth. that's worse than goatse"

        No you ain't seen nothing lol.

      That troll needs to be more original and yes that link is not work safe, but I find the reactions hysterical.

      --
      http://saveie6.com/
  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. Re:I did it at Apple in 1991 by hchesley · · Score: 1

      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 decentralized systems of all flavors...

    5. Re:I did it at Apple in 1991 by drb226 · · Score: 1

      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.

  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.

    1. Re:Actually... by Korin43 · · Score: 1

      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.

    2. Re:Actually... by errandum · · Score: 1

      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 is p2p based. Still cool, but not news.

    3. Re:Actually... by Fnord666 · · Score: 1

      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.

      --
      'The tyrant will always find pretext for his tyranny.' - Aesop's Fables
  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 Phizzle · · Score: 1

      Freaking awesome, thanks!

      --
      I will not be pushed, filed, stamped, indexed, briefed, debriefed or numbered. My life is my own.
    2. 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.

    3. 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. Encryption by slasho81 · · Score: 1

    Is the chat encrypted?

    1. Re:Encryption by Anonymous Coward · · Score: 1

      WASTE is encrypted and decentralized.

  8. Magnet links? by SkOink · · Score: 1, Interesting

    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?

    --
    ---- I'll take you in a Hunt deathmatch any day.
    1. Re:Magnet links? by Anonymous Coward · · Score: 1

      That's not at all how they work. magnet: URIs (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.

  9. 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.

    1. Re:It uses the DHT by burris · · Score: 1

      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.

  10. Bonjour and cspace by munky99999 · · Score: 1

    Bonjour is multicast decentralized chatting.

    http://cspace.in/

    cspace is basically what OP is speaking about.

  11. 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

    1. Re:Nice. by Kagetsuki · · Score: 1

      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.

  12. Re:MAIL by mug+funky · · Score: 1

    yes it is.

  13. 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

  14. Was done years ago! by ewanm89 · · Score: 1

    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.

  15. Re:Am I the first ham in the room? APRS was earlie by ewanm89 · · Score: 1

    ARPANET, hell, how you think the POTS works? Or even old telegraph cables. The difference is whether packet switched, broadcast or circuit switched.

  16. Re:Am I the first ham in the room? APRS was earlie by ewanm89 · · Score: 1

    I think if I chuck text files to each other over freenet, I probably have elementary distributed chat.

  17. R/W access to all torrents ? by matt007 · · Score: 1

    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.

    1. Re:R/W access to all torrents ? by marcosdumay · · Score: 1

      Latin languages use the word "si" or "se" for the english "if". I guess the GP failed at translating his tought.

      --
      Rethinking email
  18. Re:Prior Art by flimflammer · · Score: 1

    Prior art? This isn't a patent

  19. Nice idea by MichaelSmith · · Score: 1

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

    --
    http://michaelsmith.id.au