|Type||peer-to-peer, key-value store|
|License||Apache License 2|
TomP2P is a distributed hash table which provides a decentralized key-value infrastructure for distributed applications. Each peer has a table that can be configured either to be disk-based or memory-based to store its values.
TomP2P stores key-value pairs in a distributed hash table. To find the peers and store the data in the distributed hash table, TomP2P uses an iterative routing approach. The underlying protocol for all the communication with other peers uses state-less request-reply messaging. Since TomP2P uses non-blocking communication, a future object is required to keep track of future results. This key concept is used for all the communication (iterative routing and DHT operations, such as storing a value on multiple peers) in TomP2P and it is also exposed in the API. Thus, an operation such as
put(...) will return immediately and the user of the API can either block the operation to wait for the completion or add a listener that gets notified when the operation completes.
Freenet is a peer-to-peer platform for censorship-resistant, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship. Both Freenet and some of its associated tools were originally designed by Ian Clarke, who defined Freenet's goal as providing freedom of speech on the Internet with strong anonymity protection.
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.
JXTA (Juxtapose) was an open-source peer-to-peer protocol specification begun by Sun Microsystems in 2001. The JXTA protocols were 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.
BitTorrent is a communication protocol for peer-to-peer file sharing (P2P), which enables users to distribute data and electronic files over the Internet in a decentralized manner.
GNUnet is a software framework for decentralized, peer-to-peer networking and an official GNU package. The framework offers link encryption, peer discovery, resource allocation, communication over many transports and various basic peer-to-peer algorithms for routing, multicast and network size estimation.
In computing, Chord is a protocol and algorithm for a peer-to-peer distributed hash table. A distributed hash table stores key-value pairs by assigning keys to different computers ; a node will store the values for all the keys for which it is responsible. Chord specifies how keys are assigned to nodes, and how a node can discover the value for a given key by first locating the node responsible for that key.
Kademlia is a distributed hash table for decentralized peer-to-peer computer networks designed by Petar Maymounkov and David Mazières in 2002. 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 node ID serves not only as identification, but the Kademlia algorithm uses the node ID to locate values.
An overlay network is a computer network that is layered on top of another network.
Key-based routing (KBR) is a lookup method used in conjunction with distributed hash tables (DHTs) and certain other overlay networks. While DHTs provide a method to find a host responsible for a certain piece of data, KBR provides a method to find the closest host for that data, according to some defined metric. This may not necessarily be defined as physical distance, but rather the number of network hops.
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.
A BitTorrent tracker is a special type of server that assists in the communication between peers using the BitTorrent protocol.
Peer Name Resolution Protocol (PNRP) is a peer-to-peer protocol designed by Microsoft. PNRP enables dynamic name publication and resolution, and requires IPv6.
Peer exchange or PEX is a communications protocol that augments the BitTorrent file sharing protocol. It allows a group of users that are collaborating to share a given file to do so more swiftly and efficiently.
Pastry is an overlay network and routing network for the implementation of a distributed hash table (DHT) 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 via the routing table which is dynamically built and repaired. It is claimed that because of its redundant and decentralized nature there is no single point of failure and any single node can leave the network at any time without warning and with little or no chance of data loss. The protocol is also capable of using a routing metric supplied by an outside program, such as ping or traceroute, to determine the best routes to store in its routing table.
Magma is a distributed file system based on a distributed hash table, written in C, compatible with Linux and BSD kernels using FUSE.
In the BitTorrent file distribution system, a torrent file or meta-info file is a computer file that contains metadata about files and folders to be distributed, and usually also a list of the network locations of trackers, which are computers that help participants in the system find each other and form efficient distribution groups called swarms. A torrent file does not contain the content to be distributed; it only contains information about those files, such as their names, folder structure, sizes, and cryptographic hash values for verifying file integrity. The term torrent may refer either to the metadata file or to the files downloaded, depending on the context.
Mainline DHT is the name given to the Kademlia-based distributed hash table (DHT) used by BitTorrent clients to find peers via the BitTorrent protocol. The idea of using a DHT for distributed tracking in BitTorrent was first implemented in Azureus 220.127.116.11 in May 2005, from which it gained significant popularity. Unrelated but around the same time, BitTorrent, Inc. released a similar DHT into their client called Mainline DHT, and thus popularized the use of distributed tracking in the BitTorrent protocol. Measurement showed that by 2013, the concurrent number of users of Mainline DHT is from 16 million to 28 million, with intra-day changes of at least 10 million.
Twister is an experimental peer-to-peer microblogging program. It is decentralized; consequently it cannot be shut down by an attack as there is no single point to attack. The system uses end-to-end encryption to safeguard communications. It is based on both BitTorrent- and Bitcoin-like protocols and has been likened to a distributed version of Twitter.
Elliptics is a distributed key–value data storage with open source code. By default it is a classic distributed hash table (DHT) with multiple replicas put in different groups. Elliptics was created to meet requirements of multi-datacenter and physically distributed storage locations when storing huge amount of medium and large files.
ZeroNet is a decentralized web-like network of peer-to-peer users, created by Tamas Kocsis in 2015, programming for the network was based in Budapest, Hungary; is built in Python; and is fully open source. Instead of having an IP address, sites are identified by a public key. The private key allows the owner of a site to sign and publish changes, which propagate through the network. Sites can be accessed through an ordinary web browser when using the ZeroNet application, which acts as a local webhost for such pages. In addition to using bitcoin cryptography, ZeroNet uses trackers from the BitTorrent network to negotiate connections between peers. ZeroNet is not anonymous by default, but it supports routing traffic through the Tor network.