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Distributed Hash Table
A distributed hash table (DHT) is a distributed system that provides a lookup service similar to a hash table: key–value pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key. The main advantage of a DHT is that nodes can be added or removed with minimum work around re-distributing keys. ''Keys'' are unique identifiers which map to particular ''values'', which in turn can be anything from addresses, to documents, to arbitrary data. 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 a DHT to scale 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 more complex services, such as anycast, cooperative web caching, distributed file systems, domain name services, instant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Distributed Computing
A distributed system is a system whose components are located on different networked computers, which communicate and coordinate their actions by passing messages to one another from any system. Distributed computing is a field of computer science that studies distributed systems. The components of a distributed system interact with one another in order to achieve a common goal. Three significant challenges of distributed systems are: maintaining concurrency of components, overcoming the lack of a global clock, and managing the independent failure of components. When a component of one system fails, the entire system does not fail. Examples of distributed systems vary from SOA-based systems to massively multiplayer online games to peer-to-peer applications. A computer program that runs within a distributed system is called a distributed program, and ''distributed programming'' is the process of writing such programs. There are many different types of implementations for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Kad Network
The Kad network is a peer-to-peer (P2P) 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. Usage The Kad network uses a UDP-based protocol to: * Find sources for eD2k hashes. * Search for eD2k hashes based on keywords in the file name. * Find comments and ratings for files (hashes). * Provide buddy services for firewalled ( Low ID) nodes. * Store locations, comments and (keywords out of) filenames. Note that the Kad network is not used to actually transfer files across the P2P network. Instead, when a file transfer is initiated, clients connect directly to each other (using the standard public IP network). This traffic is susceptible to blocking/shaping/tracking by an ISP or any other opportunistic middle-man. As with all decentralized netwo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Query Flooding
Query flooding is a method to search for a resource on a peer-to-peer network. It is simple and scales very poorly and thus is rarely used. Early versions of the Gnutella protocol operated by query flooding; newer versions use more efficient search algorithms. Operation A peer-to-peer network generally consists of a large number of nodes each connected to a small subset of the nodes and not all nodes in the network. If a node wants to find a resource on the network, which may be on a node it does not know about, it could simply broadcast its search query to its immediate neighbours. If the neighbours do not have the resource, it then asks its neighbours to forward the query to their neighbours in turn. This is repeated until the resource is found or all the nodes have been contacted, or perhaps a network-imposed hop limit is reached. Query flooding is simple to implement and is practical for small networks with few requests. It contacts all reachable nodes in the network and so c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hard Disk
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box. Introduced by IBM in 1956, HDDs were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers, though personal computing devices produced in large volume, like cell phones and tablets, re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Napster
Napster was a peer-to-peer file sharing application. It originally launched on June 1, 1999, with an emphasis on digital audio file distribution. Audio songs shared on the service were typically encoded in the MP3 format. It was founded by Shawn Fanning, Sean Parker, and Hugo Sáez Contreras. As the software became popular, the company ran into legal difficulties over copyright infringement. It ceased operations in 2001 after losing a wave of lawsuits and filed for bankruptcy in June 2002. Later, more decentralized projects followed Napster's P2P file-sharing example, such as Gnutella, Freenet, FastTrack, and Soulseek. Some services and software, like AudioGalaxy, LimeWire, Scour, Kazaa / Grokster, Madster, and eDonkey2000, were also brought down or changed due to copyright issues. Napster's assets were eventually acquired by Roxio, and it re-emerged as an online music store. Best Buy later purchased the service and merged it with its Rhapsody service on December ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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BitTorrent (software)
BitTorrent is a proprietary adware BitTorrent client developed by Bram Cohen and Rainberry, Inc. used for uploading and downloading files via the BitTorrent protocol. BitTorrent was the first client written for the protocol. It is often nicknamed Mainline by developers denoting its official origins. Since version 6.0 the BitTorrent client has been a rebranded version of μTorrent. As a result, it is no longer open source. It is currently available for Microsoft Windows, Mac, Linux, iOS and Android. There are currently two versions of the software, "BitTorrent Classic" which inherits the historical version numbering, and "BitTorrent Web", which uses its own version numbering. History Programmer Bram Cohen designed the protocol in April 2001 and released a first implementation of the BitTorrent client on 2 July 2001. It is now maintained by Cohen's company BitTorrent, Inc. Prior to version 6.0, BitTorrent was written in Python, and was free software. Very early versions relea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gnutella
Gnutella is a peer-to-peer network protocol. Founded in 2000, it was the first decentralized peer-to-peer network of its kind, leading to other, later networks adopting the model. In June 2005, Gnutella's population was 1.81 million computers increasing to over three million nodes by January 2006.On the Long-term Evolution of the Two-Tier Gnutella Overlay Rasti, Stutzbach, Rejaie, 2006. See Figure 2a. In late 2007, it was the most popular file-sharing network on the Internet with an estimated market share of more than 40%. History The first client (also called Gnutella) from which the network got its name was developed by |
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Peer-to-peer
Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a peer-to-peer network of nodes. Peers 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 by servers or stable hosts. Peers are both suppliers and consumers of resources, in contrast to the traditional client–server model in which the consumption and supply of resources are divided. While P2P systems had previously been used in many application domains, the architecture was popularized by the file sharing system Napster, originally released in 1999. The concept has inspired new structures and philosophies in many areas of human interaction. In such social contexts, peer-to-peer as a meme refers to the egalitari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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InterPlanetary File System
The InterPlanetary File System (IPFS) is a protocol, hypermedia and file sharing peer-to-peer network for storing and sharing data in a distributed file system. IPFS uses content-addressing to uniquely identify each file in a global namespace connecting IPFS hosts. IPFS can among others replace the location based hypermedia server protocols and to distribute the World Wide Web.YoutubeStanford Seminar - "IPFS and the Permanent Web"- Juan Benet of Protocol LabsQuote: "...The InterPlanetary File System (IPFS) is a new hypermedia distribution protocol, to complement--and eventually replace--HTTP. It improves the security, performance, operation modes, and data friendliness of the Web. In particular, it yields a powerful new model, where websites and web applications are decoupled from origin servers, are distributed trustlessly through the network, and are encrypted, authenticated, and executed safely..." Design IPFS allows users to host and receive content in a manner simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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YaCy
''YaCy'' (pronounced “ya see”) is a free distributed search engine, built on the principles of peer-to-peer (P2P) networks created by Michael Christen in 2003. The engine is written in Java and distributed on several hundred computers, , 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 peer-to-peer. It is a search engine that everyone can use to build a search portal for their intranet and to help search the public internet clearly. Compared to semi-distributed search engines, the YaCy-network has a distributed architecture. All YaCy-peers are equal and no central server exists. It can be run either in a crawling mode or as a local proxy server, indexing web pages visited by the person running YaCy on their computer. Several mechanisms are provided to protect the user's privacy. Access ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |