Peer-to-Peer and Collective Intelligence A platform for collaboration Andrew Roczniak Collective Intelligence Lab Multimedia Communications Research Lab University of Ottawa August 9th, 2004

Agenda Examples of How P2P Works DefinitionsApplications P2P Architecture Benefits

Requesting Content WWW, HTTP

Content Distribution Networks Akamai, Digital Island

Content Distribution on P2P P2P Network

Streaming Content P2P Network

Streaming Content Infrastructure P2P Network I want content! We want content too!

Distributed Storage P2P Network I need storage space! I have some

Summary - Which Applications? Content delivery File sharing File sharing Streaming (Video conference, Audio) Streaming (Video conference, Audio)End-HostInfrastructure Network Storage

Definitions “Peer to peer is essentially a technological communications method where all parties are equal. The Web is not peer-to-peer, it has a server-to-client model. On the Web P2P refers specifically to a network established by a group of users sharing the same software program, like Napster.” Source: Condensed Net Glossary

Definitions “From user to user. Peer-to-peer implies that either side can initiate a session and has equal responsibility. Peer- to-peer is a somewhat confusing term, because it has always been contrasted to a central system that initiates and controls everything. But in practice, two users on a peer-to-peer system often require data from a third computer. For example, the infamous Napster file sharing service was always called a "peer-to-peer network," but its use of a central server to store the public directory made it both centralized and peer-to- peer“ Source:

Definitions “P2P computing is the sharing of computer resources and services by direct exchange between systems. These resources and services include exchange of information, processing cycles, cache storage, and disk storage for files.” Source: P2P Working Group

Definitions “A distributed network architecture may be called a Peer-to- Peer network, if the participants share a part of their own hardware resources (processing power, storage capacity, network link capacity, printers). These shared resources are necessary to provide the service and content offered by the network (e.g. file sharing or shared workspaces for collaboration). They are accessible by other peers directly, without passing intermediary entities. The participants of such a network are thus resource (Service and content) providers as well as resource (Service and content) requestors (Servent).” Source: R. Schollmeier, “A Definition of Peer-to-Peer Networking for the Classification of P2P Architectures and Applications”, IEEE P2P Conference, 2001

Definitions “P2P is a class of applications that takes advantage of resources e.g. storage, cycles, content, human presence, available at the edges of the Internet” Source: OpenP2P.com, Clay Shirky

What P2P is A Mind Set A system and/or application that takes advantage of resources at the edge of Internet or supports direct interaction among users. A system and/or application that takes advantage of resources at the edge of Internet or supports direct interaction among users. A Model A system and/or application that does not rely on fully centralized or client/server approach A system and/or application that does not rely on fully centralized or client/server approach An Implementation Choice Example: application layer multicast Example: application layer multicast A property of a System or an Environment Certain situations require a P2P solution (lack of infrastructure, scalability, reliability) Certain situations require a P2P solution (lack of infrastructure, scalability, reliability) From: “Peer-to-Peer Computing”, Dejan S. Milojicic et al.

Applications Instant Messaging ICQ, MSN Messenger, Lotus Sametime ICQ, MSN Messenger, Lotus SametimeBroadcasting Distributed Search Engines Group Collaboration Groove Networks Groove Networks Distributed Computing Telephony Skype Skype

P2P Architecture Benefits Cost sharing and cost reduction. A P2P architecture can help spread costs over all participants A P2P architecture can help spread costs over all participants Improved reliability No single point of failure No single point of failure Scalability and resource aggregation Peers bring resources such as bandwidth, computing power or storage space Peers bring resources such as bandwidth, computing power or storage space

P2P Architecture Characteristics Autonomy Users may be unwilling to rely on any centralized service provider Users may be unwilling to rely on any centralized service providerDynamism Peers can enter and leave the system freely Peers can enter and leave the system freely Ad-Hoc collaboration Application-level collaboration between users. Peers form a group of two or more users based on their current interests Application-level collaboration between users. Peers form a group of two or more users based on their current interests

Criteria Budget Resource Relevance to Participants Trust Rate of System Change Criticality M. Roussopoulos, M. Baker, D. S. H. Rosenthal, T.J. Giuli, P. Maniatis, J. Mogul, “2 P2P or Not 2 P2P?”, IPTPS 2004

Decision Tree ! Rate of Change ! ! ! Budget Relevance Trust Rate of Change Criticality Corporate Storage FreeNet Content Distribution Flash Crowds MP3 Sharing LowHigh LowHigh Low High Low High

Conclusion The goal of this section was to explain what P2P is P2P is more than just sharing copyright materials Questions?