What Are P2P Software Applications?
A good definition of P2P software was proposed by Dave Winer of UserLand Software many years ago when P2P was first becoming mainstream. Dave suggests that P2P software applications include these seven key characteristics:- the user interface runs outsides of a Web browser
- computers in the system can act as both clients and servers
- the software is easy to use and well-integrated
- the application includes tools to support users wanting to create content or add functionality
- the application makes connections with other users
- the application does something new or exciting
- the software supports "cross-network" protocols like SOAP or XML-RPC
Kazaa, Napster and More P2P Software Applications
The original MP3 file sharing system, Napster became the world's most popular Internet software application literally overnight. Napster typified the new "modern" P2P system defined above: a simple user interface running outside of the browser supporting both file serving and downloads. Furthermore, Napster offered chat rooms to connect its millions of users and performs a new and exciting (in the sense of "controversial") service.The name Napster referred both to the P2P network and the file sharing client that it supported. Besides being limited at the beginning to a single client application, Napster employed a proprietary network protocol, but thess technical details did not materially affect its popularity.
When the original unregulated Napster service was shut down, a number of P2P systems competed for that audience. Most Napster uses migrated to the Kazaa and Kazaa Lite software applications and the FastTrack network. FastTrack grew to become even larger than the original Napster network.
Kazaa has suffered from its own legal troubles, but various other systems, like eDonkey / Overnet, have continued the legacy of free P2P file sharing software.
Popular P2P Applications and Networks
No one P2P application or network enjoys exclusive popularity on the Internet today. Popular P2P networks include:- eDonkey
- BitTorrent
- Gnutella
- eMule
- BitTorrent
- Limewire
Summary
The "P2P" acronym has become a household term. The term refers to a combination of things: software applications, network technologies, and the ethics of file sharing.In the years ahead, expect the concept of P2P to continue evolving. The networking industry will introduce a wider range of peer to peer applications that should compete for attention with traditional desktop and client / server systems. P2P protocol standards will be adopted to a greater extent. Finally, the ramifications of free P2P application information sharing on copyright and intellectual property law will slowly be settled through the process of public debate.

