A peer-to-peer, commonly abbreviated to P2P, is any distributed network architecture composed of participants that make a portion of their resources (such as processing power, disk storage or network bandwidth) directly available to other network participants, without the need for central coordination instances (such as servers or stable hosts). Peers are both suppliers and consumers of resources, in contrast to the traditional client-server model where only servers supply, and clients consume.
Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table; (key, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given key. Responsibility for maintaining the mapping from keys to values is distributed among the nodes, in such a way that a change in the set of participants causes a minimal amount of disruption.
JXTA (Juxtapose) is an open source peer-to-peer protocol specification begun by Sun Microsystems in 2001. The JXTA protocols are defined as a set of XML messages which allow any device connected to a network to exchange messages and collaborate independently of the underlying network topology. As JXTA is based upon a set of open XML protocols, it can be implemented in any modern computer language. Implementations are currently available for Java Platform, Standard Edition, C/C++, C# and J2ME.
Legion is a computer software system variously classified as a distributed operating system, a peer-to-peer system, metacomputing software, or middleware. It is an object-based system designed to provide secure, transparent access to large numbers of machines, both to computational power and data. The project was funded by the National Science Foundation and other funding agencies, and was mostly developed at the University of Virginia by a group led by Andrew Grimshaw.
Kademlia is a distributed hash table for decentralized peer to peer computer networks designed by Petar Maymounkov and David Mazières. It specifies the structure of the network and the exchange of information through node lookups. Kademlia nodes communicate among themselves using UDP. A virtual or overlay network is formed by the participant nodes. Each node is identified by a number or node ID.
The Coral Content Distribution Network, sometimes called Coral Cache or Coral, is a free peer-to-peer content distribution network designed and operated by Michael Freedman. Coral uses the bandwidth of volunteers to mirror web content, often to avoid the Slashdot Effect or to reduce the load on websites in general.
Jigdo (portmanteau of "Jigsaw" and "download") is a download utility initially designed around the Debian distribution of GNU/Linux that downloads files from several mirrors in order to build an optical disk image. Jigdo is free software, released under the GNU General Public License. Currently Ubuntu, Fedora, Solaris, and FreeBSD are also available through Jigdo. A typical application of Jigdo is with its jigdo-file utility.
The Content Addressable Network (CAN) is a distributed, decentralized P2P infrastructure that provides hash table functionality on an Internet-like scale. CAN was one of the original four distributed hash table proposals, introduced concurrently with Chord, Pastry, and Tapestry.
YaCy (read "ya see") is a free distributed search engine, built on principles of peer-to-peer (P2P) networks. Its core is a computer program written in Java distributed on several hundred computers, as of September 2006, so-called YaCy-peers. Each YaCy-peer independently crawls through the Internet, analyzes and indexes found web pages, and stores indexing results in a common database (so called index) which is shared with other YaCy-peers using principles of P2P networks.
Octoshape is a proprietary streaming media platform. It uses throughput optimization technology to both deliver HD quality streams, as well as break through congestion in the last mile to provide more resilient delivery. It has the option of using a secure grid delivery technology to minimize the bandwidth for any CDN, ISP, broadcaster, or last mile provider to stream material.
CoDeeN is a proxy server system created at Princeton University and deployed for general use on PlanetLab. It operates as per the following: Users set their internet caches to a nearby high bandwidth proxy that participates in the system. Requests to that proxy are then forwarded to an appropriate member of the system that is in charge of the file (should be caching it) and that has sent recent updates showing that it is still alive. The file is forwarded to the proxy and thence to the client.
Background Intelligent Transfer Service (BITS) is a component of modern Microsoft Windows operating systems that facilitates prioritized, throttled, and asynchronous transfer of files between machines using idle network bandwidth. It is most commonly used by recent versions of Windows Update, Windows Server Update Services, and Systems Management Server to deliver software updates to clients, and is also used by Microsoft's instant messaging products to transfer files.
Globule is an open-source collaborative content delivery network developed at the Vrije Universiteit in Amsterdam. It is implemented as a third-party module for the Apache HTTP Server that allows any given server to replicate its documents to other Globule servers. This can improve the site's performance, maintain the site available to its clients even if some servers are down, and to a certain extent help to resist to flash crowds and the Slashdot effect.
Metalink is a cross-platform and cross-application open standard/framework/file format for programs that download, including download managers, BitTorrent clients, Web browsers, FTP clients, and P2P programs. For increased convenience, it stores the multiple download locations for a file in a single metafile with the extension . metalink. This provides reliability in case one method fails.
Pastry is an overlay and routing network for the implementation of a distributed hash table similar to Chord. The key-value pairs are stored in a redundant peer-to-peer network of connected Internet hosts. The protocol is bootstrapped by supplying it with the IP address of a peer already in the network and from then on the routing table is dynamically built and repaired.
Tapestry is a distributed hash table which provides a decentralized object location, routing, and multicasting infrastructure for distributed applications. It is composed of a peer-to-peer overlay network offering efficient, scalable, self-repairing, location-aware routing to nearby resources.
RawFlow is a provider of live p2p streaming technology that enables internet broadcasting of audio and video. Rawflow was incorporated in 2002 by Mikkel Dissing, Daniel Franklin and Stephen Dicks. Its main office is in London, UK. The company's technology is similar to Abacast and Octoshape. A peer-to-peer (or P2P) computer network relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers.
NeoEdge Networks is a Silicon Valley based technology and in-game advertising company that enables casual game publishers and developers to deliver television-like commercials within their products - frequently in the context of free-to-consumer casual game play. NeoEdge currently powers advertising for a variety of game publishers including Yahoo.
Superdistribution is an approach to distributing digital products such as software, videos, and recorded music in which the products are made publicly available and distributed in encrypted form instead of being sold in retail outlets or online shops. Such products can be passed freely among users on physical media, over the Internet or other networks, or using mobile technologies such as Bluetooth, IrDA or MMS.
Peer-to-peer wiki is a server-less system that allows wiki sites to be shared between peers. It is based on a peer-to-peer version control system, which takes care of sharing, transmitting the updates, and storing the history of pages. The first P2P wiki system was designed and implemented by Reliable Software as part of their P2P version control system, Code Co-op. Buzm is a P2P desktop application that integrates and extends TiddlyWiki.