Editing BitTorrent (section)

=== Distributed trackers ===
On 2 May 2005, Azureus 2.3.0.0 (now known as [[Vuze]]) was released,<ref>{{cite web|url=http://azureus.sourceforge.net/changelog.php|title=Vuze Changelog|publisher=Azureus.sourceforge.net|url-status=live|archive-url=https://web.archive.org/web/20061201095553/http://azureus.sourceforge.net/changelog.php|archive-date=1 December 2006}}</ref> utilizing a distributed database system. This system is a [[distributed hash table]] implementation which allows the client to use torrents that do not have a working [[BitTorrent tracker]]. A bootstrap server is instead utilized. The following month, BitTorrent, Inc. released version 4.2.0 of the Mainline BitTorrent client, which supported an alternative DHT implementation (popularly known as "[[Mainline DHT]]", outlined in a draft on their website) that is incompatible with that of Azureus. In 2014, measurement showed concurrent users of Mainline DHT to be from 10 million to 25&nbsp;million, with a daily churn of at least 10&nbsp;million.<ref>{{cite journal|last1=Wang|first1=Liang|last2=Kangasharju|first2=Jussi.|year=2013|title=Measuring Large-Scale Distributed Systems: Case of BitTorrent Mainline DHT|url=https://www.cs.helsinki.fi/u/lxwang/publications/P2P2013_13.pdf|url-status=live|journal=IEEE Peer-to-Peer|archive-url=https://web.archive.org/web/20140512225743/http://www.cs.helsinki.fi/u/lxwang/publications/P2P2013_13.pdf|archive-date=12 May 2014|access-date=15 May 2014|df=dmy-all}}</ref>

Current versions of the official BitTorrent client, [[μTorrent]], [[BitComet]], [[Transmission (BitTorrent client)|Transmission]] and BitSpirit all share compatibility with Mainline DHT. Both DHT implementations are based on [[Kademlia]].<ref>{{cite web|url=http://khashmir.sourceforge.net/ |title=Khashmir.SourceForge.net |publisher=Khashmir.SourceForge.net |access-date=9 July 2012 | archive-url = https://web.archive.org/web/20120702140624/http://khashmir.sourceforge.net/ | archive-date = 2 July 2012| url-status=live}}</ref> As of version 3.0.5.0, Azureus also supports Mainline DHT in addition to its own distributed database through use of an optional application plugin.<ref>{{cite web|url=http://azureus.sourceforge.net/plugin_details.php?plugin=mlDHT|title=plugins.vuze.com|publisher=plugins.vuze.com|url-status=live|archive-url=https://web.archive.org/web/20120801195122/http://azureus.sourceforge.net/plugin_details.php?plugin=mlDHT|archive-date=1 August 2012|access-date=9 July 2012}}</ref> This potentially allows the Azureus/Vuze client to reach a bigger swarm.

Another idea that has surfaced in Vuze is that of ''virtual torrents''. This idea is based on the distributed tracker approach and is used to describe some web resource. Currently, it is used for [[instant messaging]]. It is implemented using a special messaging protocol and requires an appropriate plugin. Anatomic P2P is another approach, which uses a decentralized network of nodes that route traffic to dynamic trackers. Most BitTorrent clients also use [[peer exchange]] (PEX) to gather peers in addition to [[BitTorrent tracker|trackers]] and [[Distributed hash table|DHT]]. Peer exchange checks with known peers to see if they know of any other peers. With the 3.0.5.0 release of Vuze, all major BitTorrent clients now have compatible peer exchange.