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26/08/2003, 03h47
A Brief History of P2P

Peer-to-peer has always existed, but hasn't always been recognized as such;servers with fixed or resolvable IP addresses have always had the capability to communicate with other servers to access services.

The most popular applications have fallen into one of three major categories : instant messaging, file sharing, and distributed computing

Instant Messaging (IM)
When Mirabilis released ICQ (www.icq.com) in November 1996, it gave its users a fast way to communicate with friends than traditional email. ICQ allows users to be notified when their friends come online and to send instant messages to their friends.

ICQ allows users to exchange files. ICQ relies on a hybrid of the P2P and clientserver architectures to provide its service, ICQ uses a central server to monitor which users are currently online and to notify interested parties when new users connect to the network.

All other communication between users is conducted in a P2P fashion, with messages flowing directly from one user's machine to another's with no server intermediary.

ICQ has had many imitators, including MSN Messenger (www.messenger.msn.com), AOL Internet Messenger (www.aol.com/aim), and Yahoo! Messenger (www.messenger.yahoo.com). Sadly, these applications are not compatible; each relies on its own proprietary communication protocol. As a result of this incompatibility, users must download different client software and go through a separate registration process for each network. Because most users choose to avoid this inconvenience, these networks have grown into completely separate user communities that cannot interact.

More recently, various software developers have tried to brigde these separate communities by reverse-engineering the IM protocols and making new client software. One such application, Jabber (www.jabber.com), provides gateways to all major IM services, allowing users to interact with each other across the various IM networks. This attempt has met with resistance from service providers, prompting AOL to change its communication protocol in an attempt to block Jabber clients.