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).[1] Peers are both suppliers and consumers of resources, in contrast to the traditional client–server model where only servers supply, and clients consume.
Peer-to-peer was popularized by file sharing File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media , documents, or electronic books. It may be implemented through a variety of storage, transmission, and distribution models and common methods of file sharing incorporate manual sharing using removable media, systems like Napster Napster was an online music file sharing service created by Shawn Fanning while he was attending Northeastern University in Boston. The service operated between June 1999 and July 2001. Its technology allowed people to easily share their MP3 files with other participants, bypassing the established market for such songs and thus leading to massive. Peer-to-peer file sharing networks have inspired new structures and philosophies in other areas of human interaction. In such social contexts, peer-to-peer as a meme Peer-to-peer is a term that originated from the popular concept of peer-to-peer computer application design, popularized by the large distributed file sharing systems, such as Napster, the first of its kind in the late 1990s. The concept has inspired new structures and philosophies in other areas of human interaction. In this context it refers to refers to the egalitarian Egalitarianism , is a trend of thought that favors equality of some sort. Its general premise is that people should be treated as equals on certain dimensions such as religiously, politically, economically, socially, or culturally. Egalitarian doctrines maintain that all human persons are equal in fundamental worth or moral status. In large part, social networking A social network is a social structure made up of individuals called "nodes," which are tied (connected) by one or more specific types of interdependency, such as friendship, kinship, common interest, financial exchange, dislike, sexual relationships, or relationships of beliefs, knowledge or prestige that is currently emerging throughout society A society or a human society is a group of people related to each other through persistent relations such as social status, roles and social networks. Human societies are characterized by patterns of relationships between individuals sharing a distinctive culture and institutions. Without an article, the term refers either to the entirety of, enabled by Internet The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and technologies in general.
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Architecture of P2P systems
a network diagram of a basic peer to peer networkPeer-to-peer networks are typically formed dynamically by ad-hoc additions of nodes. In an 'ad-hoc' network, the removal of nodes has no significant impact on the network. The distributed architecture of an application in a peer-to-peer system provides enhanced scalability and service robustness.
Peer-to-peer systems often implement an Application Layer Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite define application layers overlay network An overlay network is a computer network which is built on top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network. For example, many peer-to-peer networks are overlay networks because they run on top of the native or physical network topology. Such overlays are used for indexing and peer discovery. Content is typically exchanged directly over the underlying Internet Protocol The Internet Protocol is a protocol used for communicating data across a packet-switched internetwork using the Internet Protocol Suite, also referred to as TCP/IP (IP) network. Anonymous peer-to-peer An anonymous P2P communication system is a peer-to-peer distributed application in which the nodes or participants are anonymous or pseudonymous. Anonymity of participants is usually achieved by special routing overlay networks that hide the physical location of each node from other participants systems are an exception, and implement extra routing layers to obscure the identity of the source or destination of queries.
In structured peer-to-peer networks, connections in the overlay are fixed. They typically use distributed hash table Distributed hash tables 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-based (DHT) indexing, such as in the Chord system (MIT The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological research. MIT is one of two private land-grant universities[b] and is also a sea-grant and space-).[2]
Unstructured peer-to-peer networks do not provide any algorithm for organization or optimization of network connections.[citation needed] In particular, three models of unstructured architecture are defined. In pure peer-to-peer systems the entire network consists solely of equipotent peers. There is only one routing layer, as there are no preferred nodes with any special infrastructure function. Hybrid peer-to-peer systems allow such infrastructure nodes to exist, often called supernodes [3]. In centralized peer-to-peer systems, a central server is used for indexing functions and to bootstrap the entire system.[citation needed] Although this has similarities with a structured architecture, the connections between peers are not determined by any algorithm. The first prominent and popular peer-to-peer file sharing File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media , documents, or electronic books. It may be implemented through a variety of storage, transmission, and distribution models and common methods of file sharing incorporate manual sharing using removable media, system, Napster, was an example of the centralized model. Gnutella Gnutella was the first decentralized file sharing network. It celebrated a decade of existence on March 14, 2010 and has a user base in the millions. In late 2007, it was the most popular file sharing network on the Internet with an estimated market share of more than 40%. In June 2005, gnutella's population was 1.81 million computers increasing and Freenet Freenet is a decentralized, censorship-resistant distributed data store originally designed by Ian Clarke. According to Clarke, Freenet aims to provide freedom of speech through a peer-to-peer network with strong protection of anonymity; as part of supporting its users' freedom, Freenet is free and open source software. Freenet works by pooling, on the other hand, are examples of the decentralized model. Kazaa Kazaa Media Desktop started as a peer-to-peer file sharing application using the FastTrack protocol licensed by Joltid Ltd. and operated as Kazaa by Sharman Networks. Kazaa is now run under license as a music subscription service by Brilliant Digital Entertainment, Inc is an example of the hybrid model.
P2P networks are typically used for connecting nodes In communication networks, a node is a connection point, either a redistribution point or a communication endpoint (some terminal equipment). The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of sending, receiving, or via largely ad hoc A wireless ad hoc network is a decentralized wireless network. The network is ad hoc because it does not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed wireless networks. Instead, each node participates in routing by forwarding data for other nodes, and so the determination of which nodes connections.[citation needed] Sharing content files (see file sharing File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media , documents, or electronic books. It may be implemented through a variety of storage, transmission, and distribution models and common methods of file sharing incorporate manual sharing using removable media,) containing audio, video, data or anything in digital format is very common, and real time data, such as telephony Voice over Internet Protocol is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VOIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, traffic, is also passed using P2P technology.
A pure P2P network does not have the notion of clients A client is an application or system that accesses a remote service on another computer system, known as a server, by way of a network. The term was first applied to devices that were not capable of running their own stand-alone programs, but could interact with remote computers via a network. These dumb terminals were clients of the time-sharing or servers but only equal peer In computer networking, a peer group is a group of functional units in the same layer of a network, by analogy with peer group. See also peer-to-peer (P2P) networking which is a specific type of networking relying on basically equal end hosts rather than on a hierarchy of devices nodes that simultaneously function as both "clients" and "servers" to the other nodes on the network. This model of network arrangement differs from the client–server model where communication is usually to and from a central server. A typical example of a file transfer that is not P2P is an FTP File Transfer Protocol is a standard network protocol used to copy a file from one host to another over a TCP/IP-based network, such as the Internet. FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server applications, which solves the problem of different end host server where the client and server programs are quite distinct: the clients initiate the download/uploads, and the servers react to and satisfy these requests.
The P2P overlay network An overlay network is a computer network which is built on top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network. For example, many peer-to-peer networks are overlay networks because they run consists of all the participating peers as network nodes. There are links between any two nodes that know each other: i.e. if a participating peer knows the location of another peer in the P2P network, then there is a directed edge from the former node to the latter in the overlay network. Based on how the nodes in the overlay network are linked to each other, we can classify the P2P networks as unstructured or structured.
Structured systems
Structured P2P networks employ a globally consistent protocol to ensure that any node can efficiently route a search to some peer that has the desired file, even if the file is extremely rare. Such a guarantee necessitates a more structured pattern of overlay links. By far the most common type of structured P2P network is the distributed hash table Distributed hash tables 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 (DHT), in which a variant of consistent hashing Consistent hashing is a scheme that provides hash table functionality in a way that the addition or removal of one slot does not significantly change the mapping of keys to slots. In contrast, in most traditional hash tables, a change in the number of array slots causes nearly all keys to be remapped. By using consistent hashing, only K/n keys is used to assign ownership of each file to a particular peer, in a way analogous to a traditional hash table In computer science, a hash table or hash map is a data structure that uses a hash function to map identifying values, known as keys, to their associated values (e.g., their telephone number). The hash function is used to transform the key into the index (the hash) of an array element (the slot or bucket) where the corresponding value is to be's assignment of each key to a particular array slot.
Distributed hash tables
Distributed hash tablesDistributed hash tables Distributed hash tables 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 (DHTs) are a class of decentralized distributed systems Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal. A computer program that runs in a distributed system is called a distributed that provide a lookup service similar to a hash table In computer science, a hash table or hash map is a data structure that uses a hash function to map identifying values, known as keys, to their associated values (e.g., their telephone number). The hash function is used to transform the key into the index (the hash) of an array element (the slot or bucket) where the corresponding value is to be: (key, value) pairs are stored in the DHT, and any participating node In communication networks, a node is a connection point, either a redistribution point or a communication endpoint (some terminal equipment). The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of sending, receiving, or 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. This allows DHTs to scale In telecommunications and software engineering, scalability is a desirable property of a system, a network, or a process, which indicates its ability to either handle growing amounts of work in a graceful manner or to be readily enlarged. For example, it can refer to the capability of a system to increase total throughput under an increased load to extremely large numbers of nodes and to handle continual node arrivals, departures, and failures.
DHTs form an infrastructure that can be used to build peer-to-peer networks. Notable distributed networks that use DHTs include BitTorrent's BitTorrent is a peer-to-peer file sharing protocol used for distributing large amounts of data. BitTorrent is one of the most common protocols for transferring large files, and it has been estimated that it may account for as much as 43 % of all Internet traffic as of February 2009 distributed tracker, the Bitcoin monetary network, the Kad network The Kad network is a peer-to-peer network which implements the Kademlia P2P overlay protocol. The majority of users on the Kad Network are also connected to servers on the eDonkey network, and Kad Network clients typically query known nodes on the eDonkey network in order to find an initial node on the Kad network, the Storm botnet The Storm botnet or Storm worm botnet is a remotely controlled network of "zombie" computers (or "botnet") that has been linked by the Storm Worm, a Trojan horse spread through e-mail spam. Some have estimated that by September 2007 the Storm botnet was running on anywhere from 1 million to 50 million computer systems. Other, YaCy YaCy 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[update], so-called YaCy-peers. Each YaCy-peer independently crawls through the Internet, analyzes and indexes found web pages, and stores, and the Coral Content Distribution Network 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.
Some prominent research projects include the Chord project, the PAST storage utility, the P-Grid P-Grid is a self-organizing structured peer-to-peer system, which can accommodate arbitrary key distributions , still providing storage load-balancing and efficient search by using randomized routing, a self-organized and emerging overlay network and the CoopNet content distribution system CoopNet , a system for off-loading serving to peers who have recently downloaded content, is described in the paper “The Case for Cooperative Networking”, presented at the First International Workshop on Peer-to-Peer Systems (IPTPS) in 2002. The system was proposed by computer scientists Venkata N. Padmanabhan and Kunwadee Sripanidkulchai, (see below for external links related to these projects).
DHT-based networks have been widely utilized for accomplishing efficient resource discovery[4][5] for grid computing systems, as it aids in resource management and scheduling of applications. Resource discovery activity involve searching for the appropriate resource types that match the user’s application requirements. Recent advances in the domain of decentralized resource discovery have been based on extending the existing DHTs with the capability of multi-dimensional data organization and query routing. Majority of the efforts have looked at embedding spatial database indices such as the Space Filling Curves (SFCs) including the Hilbert curves, Z-curves, k-d tree, MX-CIF Quad tree and R*-tree for managing, routing, and indexing of complex Grid resource query objects over DHT networks. Spatial indices are well suited for handling the complexity of Grid resource queries. Although some spatial indices can have issues as regards to routing load-balance in case of a skewed data set, all the spatial indices are more scalable in terms of the number of hops traversed and messages generated while searching and routing Grid resource queries.
Unstructured systems
An unstructured P2P network is formed when the overlay links are established arbitrarily. Such networks can be easily constructed as a new peer that wants to join the network can copy existing links of another node and then form its own links over time. In an unstructured P2P network, if a peer wants to find a desired piece of data in the network, the query has to be flooded A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, through the network to find as many peers as possible that share the data. The main disadvantage with such networks is that the queries may not always be resolved. Popular content is likely to be available at several peers and any peer searching for it is likely to find the same thing. But if a peer is looking for rare data shared by only a few other peers, then it is highly unlikely that search will be successful. Since there is no correlation In statistics, correlation and dependence are any of a broad class of statistical relationships between two or more random variables or observed data values between a peer and the content managed by it, there is no guarantee that flooding will find a peer that has the desired data. Flooding also causes a high amount of signaling traffic in the network and hence such networks typically have very poor search efficiency. Many of the popular P2P networks are unstructured.
In pure P2P networks: Peers act as equals, merging the roles of clients and server. In such networks, there is no central server managing the network, neither is there a central router. Some examples of pure P2P Application Layer Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite define application layers networks designed for file sharing are Gnutella (pre v0.4) and Freenet.
There also exist hybrid P2P systems, which distribute their clients into two groups: client nodes and overlay nodes. Typically, each client is able to act according to the momentary need of the network and can become part of the respective overlay network An overlay network is a computer network which is built on top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network. For example, many peer-to-peer networks are overlay networks because they run used to coordinate the P2P structure. This division between normal and 'better' nodes is done in order to address the scaling problems on early pure P2P networks. Examples for such networks are for example Gnutella (after v0.4) or G2 Gnutella2, often referred to as G2, is a peer-to-peer protocol developed mainly by Michael Stokes and released in 2002. While inspired by the gnutella protocol, G2 shares little of its design with the exception of its connection handshake and download mechanics. It adopts an extensible binary packet format and an entirely new search algorithm.
Another type of hybrid P2P network are networks using on the one hand central server(s) or bootstrapping mechanisms, on the other hand P2P for their data transfers. These networks are in general called 'centralized networks' because of their lack of ability to work without their central server(s). An example for such a network is the eDonkey network The eDonkey network is a decentralized, mostly server-based, peer-to-peer file sharing network best suited to share big files among users, and to provide long term availability of said files. In practice, it is generally used to share video files, full music albums and computer programs. Like most file sharing networks, it is decentralized, as (eD2k).
Indexing and resource discovery
Older peer-to-peer networks duplicate resources across each node in the network configured to carry that type of information. This allows local searching, but requires much traffic.
Modern networks use central coordinating servers and directed search requests. Central servers are typically used for listing potential peers (Tor Tor is a free software descendent of second-generation onion routing enabling Internet anonymity by thwarting network traffic analysis. The current project never uses all caps for the name Tor, and does not consider it to be an abbreviation), coordinating their activities (folding@home Folding@home (sometimes abbreviated as FAH or F@h) is a distributed computing (DC) project designed to perform computationally intensive simulations of protein folding and other molecular dynamics (MD), and to improve on the methods available to do so. It was launched on October 1, 2000, and is currently managed by the Pande Group, within Stanford), and searching (Napster Napster was an online music file sharing service created by Shawn Fanning while he was attending Northeastern University in Boston. The service operated between June 1999 and July 2001. Its technology allowed people to easily share their MP3 files with other participants, bypassing the established market for such songs and thus leading to massive, eMule eMule is a free peer-to-peer file sharing application for Microsoft Windows. Started in May 2002 as an alternative to eDonkey2000, eMule now connects to both the eDonkey network and the Kad network. The distinguishing features of eMule are the direct exchange of sources between client nodes, fast recovery of corrupted downloads, and the use of a). Decentralized searching was first done by flooding search requests out across peers. More efficient directed search strategies, including supernodes and distributed hash tables, are now used.
Many P2P systems use stronger peers (super-peers, super-nodes) as servers and client-peers are connected in a star-like fashion to a single super-peer.
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Fri, 27 Aug 2010 15:39:07 GMT+00:00
PC Magazine The Federal Trade Commission has closed its investigation into peer-to-peer site LimeWire, though the agency said it remained concerned about the security ... FTC drops P2P file sharing probe of LimeWire Computerworld FTC Drops LimeWire Investigation RedOrbit FTC Drops Probe of LimeWire IT Business Edge (blog) Spacelab - Inquirer - Reuters Canada
SoftwarePeer
Sat, 04 Sep 2010 09:25:55 GM
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Q. I can't get anything on my ipod without paying I thought it said it was free. All I can find are songs with the gold icon. Is there a better peer to peer site that is actually free?
Asked by coley200722 - Sat Oct 24 21:28:44 2009 - - 2 Answers - 0 Comments
A. Limewire Frostwire
Answered by anom - Sat Oct 24 21:32:40 2009
