Peer-to-peer computing over the Internet. Just a fancy way of saying "steal free MP3s with Napster or Gnutella"? Think again.
Tim O'Reilly, publisher and proprietor of O'Reilly & Associates, brought together leading players throughout the nascent P2P market space last September for a wide-ranging discussion of P2P's remarkable potential. The rough consensus amongst the new P2P movers and shakers: think of P2P as "an operating system for the Internet."
Operating systems deliver services, and P2P's go far beyond file sharing. For example, P2P may enable next-generation instant messaging and presence management. It may make possible entirely new forms of collaboration, starting with ad-hoc peer-to-peer software development workgroups.
P2P can leverage distributed computation, where millions of PCs -- whose processing cycles are mostly wasted -- share tasks too large for any individual system to perform. (Proof of concept: SETI@home, wherein over 2.5 million PCs worldwide have contributed data analysis to the search for extraterrestrial intelligence).
P2P can lead to revolutionary new Web services, new ways to hyperlink, and a whole new view of the Web, where millions of people aren't just passively consuming content and services: they're providing them as well.
One outgrowth of last Fall's P2P summit is a remarkable book: Peer-to-Peer: Harnessing the Disruptive Potential of Collaborative Networking. In this book, P2P's leading practitioners offer in-depth, technically significant discussions of nearly all the key issues they face in transforming P2P from hope to reality. O'Reilly's worked hard to find people who have something important to say and framed the book with its own thoughtful commentary. The result is nothing less than a first sketch of the next Internet revolution as it takes shape.
Section I of this book offers much-needed perspective. Nelson Minar and Marc Hedlund point out that the Internet began as a peer-to-peer operation (all the original ARPANET hosts were equal peers), and that early applications like Usenet implemented decentralized control mechanisms that have echoes in today's newest thinking about P2P.
In a brilliant essay entitled Listening to Napster, Clay Shirky starts by precisely defining P2P as "a class of applications that takes advantage of resources -- storage, cycles, content, human presence -- available at the edge of the Internet." Shirky outlines the important technical implications that flow from this definition; then informs P2P with the common-sense lessons we've learned about the Internet and other technologies: "Users reward simplicity," "It's the applications, stupid," and "Decentralization is a tool, not a goal."
Finally, Dan Bricklin, inventor of VisiCalc -- the first spreadsheet and the classic PC killer app -- makes the case that Napster "harnesses the disruptive potential of personal selfishness." The more downloads, the more resources are available to everyone: "...increasing the value of the database, by adding more information, is a natural by-product of each person using the tool for his or her own benefit." (Bricklin has his doubters, who wonder how well P2P applications will scale when 50 people take resources for each one who provides them.)
Part II of this book focuses on several real-world P2P projects. In addition to SETI@home, you'll find coverage of Jabber, an open source, XML-based instant messaging system that lets you chat with folks on AOL IM, ICQ, MSN, Yahoo, and IRC, all from the same client software. There are chapters on P2P applications intended to protect individual email privacy (Mixmaster), resist censorship (Red Rover), allow for anonymous uploads and downloads (Freenet and Free Haven), and make it possible to publish anonymously, like James Madison in The Federalist Papers (Publius).
Part III focuses on the technology of P2P: the crucial role of metadata; performance optimization; building networks that don't rely on trust; making resource hogs accountable; and providing security and interoperability. There's much work to be done, but you'll be surprised how much thought and sweat have gone into these issues.
It remains to be seen whether the P2P revolution will meet its potential. But if it does, people will view this book as the manifesto that made it all come together.(Bill Camarda)
Bill Camarda is a consultant and writer with nearly 20 years' experience in helping technology companies deploy and market advanced software, computing, and networking products and services. His 15 books include Special Edition Using Word 2000 and Upgrading & Fixing Networks For Dummies®, Second Edition.