P2P Computing

Definition

From http://thothzone.blogspot.com/2006/07/p2p-buzz-to-biz.html:

"Peer-to-peer (P2P) computing has been envisaged to solve computing scenarios which require requiring spatial distribution of computation, spatial distribution of content, real-time collaboration, ad-hoc networking, scalability or fault-tolerance at reduced costs. P2P systems provide higher storage and access capacity via distribution of resources across peers, improved reliability due to the availability of multiple peer machines and distributed security achieved by distributing partial secrets across peers. Unlike the client-server computing paradigm, where all the computation cycles and data are to be had from a single source, in P2P the participating peers contribute CPU cycles and storage space." (http://thothzone.blogspot.com/2006/07/p2p-buzz-to-biz.html)

Description

Jorn de Boever writes that:

"There is still no generally acknowledged unambiguous definition of the concept of peer to peer which causes a discussion about what can, or not, be accepted as peer to peer"

In client/server systems, centralized servers manage and control the network, provide services and resources whereas the clients consume these resources. This model suffers from inefficient allocation of resources and limited scalability. Additional users stand for additional costs as they consume more bandwidth from the system.

Nodes in peer to peer networks do not only act as clients, but they exhibit server functions as well. They have been described as servents (= SERVer plus cliENTS).

P2P systems exhibit positive network externalities in a way that additional users add value to p2p networks by introducing extra resources in the system. The network is able to self-organize itself in the absence of centralized coordinating components."

Applications

Jorn Deboever [1]:

(manual transciption from pdf file, may contain some approximate rendering)

==Instant messaging and telephony

"ICQ, AOL instant messaging and Yahoo Messenger make use of centralized peer to peer systems. The topology of these systems consists of a centralized directory server that contains information such as which nodes are online and who might communicate with whom. The communication then directly takes place between peers without intervention of the server. Skype is a peer to peer VoIP application that provides telephony, IM and audio conferencing via a peer to peer system."

Grid Computing

"It has been widely debated whether Grid Computing can be accepted as peer to peer. In either way, grid computing and peer to peer networks are both distrributed systems that are build to share resources. Grid computing is the coordinated use of resources -- computes, processor capacity, sensors, software, storage capacity, and data -- shared within a dynamic and continuously changing group of individuals. In contrasts to p2p systems, grids stress the standardized, secure and coordinated sharing of resources with a better guarantee of Quality of Service. P2P and grids might evolve into a convergence in which the benefits of grid computing (interoperability, security, QoS, and standardized infrastructure) and p2p (fault tolerance, scalability, and self organization) will be combined."

Collaborative Tools

Toolf for users to collaborate on certain tasks within groups. See Groove Virtual Office.

Filesharing and Content Distribution

"Contains both filesharing systems (Napster, Gnutella, eDonkey) and distributed storage applications (Freenet), as well as content delivery networks (Kontiki). File exchange systems are little sophisticated file sharing applications that only contains some basic functionality, and mostly does not address issues such as resource availability and security. Content publishing and storage applications are more elaborate systems to publish, distribute and store content.

Peer to peer streaming is a specific type of content distribution. Traditional streaming technologies, such as unicasting and multicasting, are characterized by the fact that additional consumers of the streaming imply more costs. In p2p streaming applications, clients act as servers as they send units of the stream to other clients in the network. Examples are RawFlow, Octoshape, Coopnet, Splitstream, Peerstreaming, and Abacast."

Wireless and Ubiquitous P2P

"Wireless communication networks can be considered p2p if the signars are being transferred directly between the appliances. The mobility of users combined with transient connectivity of nodes makes that self-organization is an even bigger challenge for wireless p2p systems".

Ubiquitous computing systems must cope with autonomous communicating systems that are marked by transient connectivity. These parallel features make that it doesn't seem illogical to integrate these systems".

Aspects

From http://thothzone.blogspot.com/2006/07/p2p-buzz-to-biz.html:

• Availability: In a federated environment, peers provided no uptime or downtime guarantee. It might so happen that the peer hosting some resource goes offline during use. As every peer can act as a server, the client peer should theoretically be able to switch over to another peer and get the resource, if available elsewhere.

• Authenticity: Remote content and behavior have to be verified since files were found not to be what they claimed and at times peers behaved maliciously. Since trust was not usually woven into the software or often ill implemented, users ran the risk of having their solitary home PC being compromised.

• Digital Piracy: The ease with which digital content could be shared in a P2P network meant that users threw caution to the winds and went about creating libraries with thousands of pirated files. In the absence of enforcement, copyright regulations were openly flouted by P2P networks like Napster. Technology was lacking and on top of it, rather than being a taboo, studies indicate that being able to a hyper-rich online media collection – pirated or purchased - became a matter of pride in user circles.

• Load Balancing: Not all content is widely available in the network. In such cases the then P2P networks degenerated to a client-server network with all traffic for the scarcer content being directed to a small number of hosts, usually with little server type resources at their disposal.

• Hardware Reliability: P2P networks usually comprise of cheaper PC hardware. Therefore, in larger networks there would be quite many failures to be dealt with. Even though data loss due to hardware failures can be avoided easily by storing data and backup on different peers, malicious peers might tamper the backup data on their local storage. • Software Reliability: Early clients were either poorly written and were overtly insecure. So it was easy to make the network disreputable among the by poisoning the network with junk files or even viruses." (http://thothzone.blogspot.com/2006/07/p2p-buzz-to-biz.html)

Examples

1. Kontiki, Qtrax, and RawFlow "exploit p2p characteristics for secure content distribution

1. Bittorrent
2. Tribler
3. Skype
4. Groove
5. Bitvault
6. Windows Collaboration
7. PeerDB

P2P for Business

"The emergence of the Distributed Hash Table (DHT) and the Bittorrent protocol can be taken as the beginning of the “Biz" era in P2P computing. Along with advancements in Digital Rights Management, storage technology, network bandwidth and software security, many niche applications of P2P have been identified and implemented, adding to the momentum. Moreover, studies conducted over the past few years, indicate business models for P2P systems are economically viable" (http://thothzone.blogspot.com/2006/07/p2p-buzz-to-biz.html)

More Information

1. Peer-to-Peer Networks as a Distribution and Publishing Model: excellent introduction!
2. The P2P Filesharing Networks are listed here: Bittorrent, Ares, eDonkey2000, Fast Track, Gnutella
3. See also the arguments in Peer to Peer - Advantages
4. DP2P Net monitors decentrazized P2P computing developments and programs.

Key Books to Read

Four are listed here