Peer-to-peer (P2P) networking
Peer-to-peer (P2P) networking
Napster: the pioneer
Napster hit the headlines in the late 1990s when it tried to subvert the monopoly of the big music publishers by providing a means for Internet users to swap music files. Although the publishers won the right to protect their 'products' (or intellectual property - Section 5.3) in the end, Napster achieved lasting fame owing to its innovative technology for connecting users' PCs. This technology is called peer-to-peer (usually abbreviated to P2P) computing and it represents a paradigm shift in the way the Web works.
What is P2P?
P2P is a way of allowing Internet-connected PCs to connect to each other directly across the Net, i.e. without going through a server. This allows the PCs to share resources such as file storage or processing power and represents truly distributed computing. This is different from the old client-server model, where the PC simply acts as a 'dumb' (but expensive) client receiving directions from the ISP server. With P2P computing the PCs are more like mutual servers using their full processing power to communicate directly with each other (via the Net) and carry out computing tasks.
The problem that P2P technology solves is that these PCs, on the edge of the Internet, are not permanently connected to the Internet. Finding them and establishing a connection when they are logged on is the key; they do not have a fixed or even predictable IP address for the system to record and use. TCP/IP and your computer, and Exercise - addresses and packets and routes in IP address is and how your PC is allocated one (and if you go in using a modem instead of an ISDN or cable line it will be a different one) every time you connect to the Internet.
P2P systems operate outside the DNS system and are not dependent on central servers. They cope with the intermittent connectivity by creating their own directories of user-specific addresses and updating the IP address information for that user in real time.
? Why is P2P so important
The following article by Clay Shirky on the O'Reilly Network is an excellent explanation of the importance of P2P and why it represents such a paradigm shift.
. summary of its key points
Collaborative or group working e.g. Groove Networks. Groove software lets you create secure shared spaces where you make instant and direct online connections with others to share information and get things done.
Distributed computing e.g. SETI@home: the search for extraterrestrial intelligence. SETI@home is a scientific experiment that uses Internet-connected computers in the Search for Extra Terrestrial Intelligence (SETI). You can participate by running a free program that downloads and analyses radio telescope data.
Distributed search engines e.g. MusicBrainz.org The MusicBrainz Metadata initiative is designed to create a portable and flexible means of storing and exchanging metadata related to digital audio and video tracks. The MusicBrainz Metadata initiative is a content description model for audio and video tracks on the Interne.
Instant messaging e.g. Jabber. The first application of Jabber technology is an instant messaging system focused on privacy, security, ease of use, access from anywhere using any device, and interoperability with Instant Messaging, phone and web-based services.
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