Peering at Peer-to-Peer

"Just as the early 20th-century advocates of psychoanalysis saw sex everywhere, industry analysts and marketing managers are starting to call everything they like in computers and telecommunications 'peer-to-peer,' writes Andy Oram in the preface to "Peer-To-Peer: Harnessing the Power of Disruptive Technologies" published by O'Reilly & Associates.

Peer-to-peer (P2P) technologies may not have the same appeal as sex, but they have seemingly become all the rage in the early years of the 21st century. Though now crippled, Napster is the poster child for P2P, and its "dark twin" Gnutella has also received a lot of press. The Seti@Home project is another highly visible P2P effort.

But P2P is hardly new, nor is it truly ubiquitous. Nonetheless, a new wave of P2P technologies are having an impact in the world of information storage and retrieval, and P2P is important subject for searchers to be aware of, at least on a basic level.

In this book, editor Oram has assembled a collection of articles penned by P2P experts. The first part of the book sets the context and provides an overview of P2P, and is probably the most useful for the non-technical reader.

The first chapter provides a great overview of P2P models through the history of the Internet, pointing out that the Net was originally conceived as a P2P network. Early protocols and tools such as Telnet, FTP, and even Usenet Newsgroups all relied on P2P approaches. The arrival of "destination" Web sites changed the nature of the Net, with single sites serving thousands or millions of users.

Even as the web morphed into a one-to-many system, P2P systems like email, instant messaging, and of course, Napster continued to thrive. The ability to share files and information directly with like-minded users, rather than relying on a centralized arbiter of content like a search engine or a portal, is what makes P2P systems so intriguing.

Napster and Gnutella allow users to search for and share files with other users. Neither system, however, is anonymous. Other P2P systems, such as Freenet, Publius, and Free Haven are similar to Gnutella but use a variety of techniques to assure anonymous retrieval of information. Moreover, they provide mechanisms for anonymous publishing of content, allowing users in countries with repressive governments to bypass draconian censorship policies.

This, of course, makes P2P appear threatening or even subversive to the establishment, which undoubtedly adds to the allure of the technology.

"Peer-To-Peer" offers in-depth looks at a number of these systems, including the ones mentioned above and others like RedRover, Jabber, the Seti@Home project, and others. While many chapters are highly technical, they also discuss many of the social issues involved with P2P technologies.

Although they focus on P2P, the chapters on Trust, Accountability, Reputation and Security are just as relevant for thinking about general-purpose search engines. Trust, accountability and reputation are actually three fundamental concepts that must be somehow be built into machine-to-machine interactions to fully realize the dream of the semantic web.

"Peer-To-Peer" offers an excellent look at an important and potentially disruptive technology that may significantly change the way we search for information. Though it's a bit technical, it's well worth the time spent slogging through the heavy details for anyone seriously interested in learning about a major future trend in the world of search.

Peer-To-Peer: Harnessing the Power of Disruptive Technologies
Edited by Andy Oram
O'Reilly & Associates
ISBN: 0-596-00110-X

Peer-To-Peer Companion Web Site

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