Product Description
The term "peer-to-peer" has come to be applied to networks that expect end users to contribute their own files, computing time, or other resources to some shared project. Even more interesting than the technology's technical underpinnings is its socially disruptive potential: in various ways these systems return content, choice, and control to ordinary users. This book presents the goals that drive the developers of the best-known peer-to-peer systems, the problems they've faced, and the technical solutions they've found. The contributors are leading developers of well-known peer-to-peer systems, including Popular Power, Jabber, Gnutella, FreeNet, SETI@Home, Red Rover, Publius, Free Haven, and Groove Networks. Topics include the Internet as a collection of conversations, metadata, performance, trust, accountability, security, and gateways between systems.

Amazon.com Review
Peer-to-Peer is a book about an emerging idea. That idea is that the traditional model of participating in the Internet, in which a small computer operated by an everyday user (a "client") asks for and receives information from a big computer administered by a corporation or other large entity (a "server"), is beginning to give some ground to a new (new to the fringes of the Internet, anyway) model called peer-to-peer networking. In peer-to-peer networking, all participants in a network are approximately equal. Furthermore, the participants are usually ordinary computers run by everyday people. The ICQ chat service and the Napster music-sharing community are examples of what this book is about.

The chief advantage of peer-to-peer networks is that large numbers of people share the burden of providing computing resources (processor time and disk space), administration effort, creativity, and--in more than a few cases--legal liability. Furthermore, it's relatively easy to be anonymous in such an environment, and it's harder for opponents of your peer-to-peer service to bring it down. The primary disadvantage of peer-to-peer systems, as anyone will attest who's had an MP3 download prematurely terminated when a dialup user went offline will attest, is the tendency of computers at the edge of the network to fade in and out of availability. Accountability for the actions of network participants is a potential problem, too.

This is a book about the idea of equipping ordinary Internet users' computers with mechanisms that enable them to connect, more or less automatically and without human attention, to other everyday Internet users' machines. By forming networks of computers at the so-called "edge" of the Internet, it's possible to offer valuable services without the burden of building and administering large, centralized computer systems of the sort that host traditional Web sites. Napster is the most successful example to date, though nerds will note that it's not a completely peer-to-peer system because users register their file libraries with a central server when they log on to the service.

Don't approach this book expecting to learn how to build the next Napster system. It's not a how-to book. It's not even much of a why-to book. Rather, it's a book that aims to get its readers thinking about what happens when information systems shift away from the client-server model and toward the peer-to-peer model (that's one of the book's points, by the way, that this is not a one-or-the-other architectural decision).

Mostly, Peer-to-Peer makes its point by letting experts in peer-to-peer take turns in the spotlight. Any other approach would be kind of ironic, wouldn't it? In any case, David Anderson explains how SETI@home puts space buffs' idle computing cycles to use in analyzing radio noise from outer space. Gene Kan explains how Gnutella (a truly serverless environment) works. The architects of Publius explain how distributed computing is especially resistant to censorship and denial-of-service attacks. Other contributors discuss peer-to-peer chat software, anonymous remailing services, and other applications of peer-to-peer design.

There's no one from Napster represented as an author in this collection of essays, but Clay Shirky presents an essay called "Listening to Napster." In that essay, Shirky gives an opinion on why Napster has succeeded: It focused on providing something consumers wanted, and bypassed Internet conventions (like the Domain Naming System) because they weren't the best way to provide the service. This is not an earth-shattering revelation, but it's true, and it's something developers of any new service (Internet-based or otherwise) need to keep in mind.

Some of the technical proposals presented here will get readers thinking. An example: Require that senders of e-mail solve a moderately complex math problem before recipients' mailboxes will accept their mail. The problem would be no big deal for a mailer to solve if he or she were sending messages one at a time, but the processor load would really add up for spammers who blast tens of thousands of unwanted emails onto the Internet in a single session. Another idea: mechanizing the concept of reputation so people know whose thoughts and whose creative works (like software) are worth using or believing.

More business-oriented readers might want to read more about the more subtle ways of incorporating peer-to-peer components into business models. Lots of traditional Web services--Amazon.com is an example--are supplementing their client-server activities with others that have peer-to-peer characteristics. Amazon.com, for example, lets operators of small Web sites promote goods and rely on the centralized resources for billing and fulfillment. There's no distributed software (other than a few links), but the company takes advantage of creativity and marketing efforts outside of its official core. Coverage of that sort of "soft" distributed computing might be a good supplement for the second edition of this book.

Peer-to-Peer is a thought-provoking book that will help its readers understand an exciting, still-emerging application architecture for the Internet. --David Wall

Topics covered: Peer-to-peer applications that run at the edges of the Internet, usually on home computers run by ordinary people. Much of this book comprises case studies on SETI@home, Gnutella, Freenet, Jabber, and other peer-to-peer services. Later chapters address technical issues, such as accountability, security, efficient use of limited bandwidth, and data cataloging.

CUSTOMER REVIEWS (Average Customer Rating: 4.5 based on 21 reviews)

This book changed my life

I work in the MP3 player industry, so the title of my review is only a slight exaggeration. P2P technology created the MP3 revolution. This book takes an honest look back at where P2P came from and where it is going from several different viewpoints. I think it is a must-read for anyone working on the future architecture of computing technology. And it is just plain interesting if you are sitting on the sidelines--and you might just find a role you can play in the game.
November 22, 2005

Still the best overview I know of

It's five years old by now, which is a long time in this industry, but the book remains relevant by virtue of the solid writing and lack of fluff that we expect from O'Reilly, and by the third section's excellent in-depth coverage of fundamental issues: Performance, Trust, Accountability, Reputation, Security. Each of these has a lot of valuable information, references and ideas.

Particularly valuable to me were the discussions of:
- Analyzing and optimizing peer connection graphs
- How Groove uses cryptography to protect and authenticate data
- Using token economies and "nonfungible micropayments" to avoid denial-of-service attacks
- How trust relationships can be tracked

The coverage of specific technologies hasn't aged quite as well. There's too much on things that either never went anywhere (Red Rover?) or are extremely primitive by today's standards (Gnutella), while very important more recent ones like BitTorrent and Kademlia are understandably missing.

Still, as I said, I don't think there's a better book out there. I've bought others and been disappointed by their superficiality, even the "academic" books. Buy this one, and then be prepared to do some intensive web searching/surfing for research papers to catch up on later developments like Distributed Hash Tables, BitTorrent, Kademlia, Chord, Pastry, Coral, JXTA, PNRP, Bonjour...
September 21, 2005

Excellent coverage of p2p

In 2000, O'Reilly surveyed the field of peer-to-peer computing, and published this book. It has an excellent description of the key concepts behind all the major p2p implementations then existing. Napster, of course, was the best known. But Seti@home, Gnutella, Jabber, Freenet, Free Haven and others are also explained. These are compared with each other, so that you can see the different emphases and strengths of each.

Since the book's release, p2p usage has grown, and the attendant controversy about the downloading of copyrighted material, mainly music, has continued unabated. Napster in its original incarnation has gone. But other p2p networks, like Kazaa, have arisen.

Another type of p2p network has also emerged - for social networks. Companies include Friendster, Tribe.net, Ryze and others. Of course, these aren't covered in the book, because they did not exist when it was written. But as a measure of how comprehensive the book is, one of its chapters describes the key work on social networks and encompasses this entire group of companies.

The technical level is moderate throughout the book. While XML, SOAP and cryptography are described, you only need slight familiarity with these topics. The discussion involving them tends to be at a higher level of usage.
March 12, 2004

dasper

I've been a big fan of O'Reilly & Associates for years because of their consistent ability to provide highly readable and accurate technical books, often about technologies I find fascinating and useful. To me the editorial bias of most of those books is simply the love of the technology they describe. But O'Reilly has increasingly become a force in the organization and direction of new technologies. And it is that aspect of this book on P2P which has made the biggest impression on me. This book is different from the many other O'Reilly books I've read because it discusses the publisher's own ideas about P2P and involvement with it.
July 25, 2002

A Great Summary

This book provides a great summary of current P2P projects and the technologies used. It is non-technical book that would be a great intro to P2P, especially for "suits" who only think of Napster when you mention the word P2P. There are loads of gems in this text; I recommend this book to any computer enthusiast.

The chapters start out strong, but I lost interest in a few of latter chapters, which tend to be a little redundant. There seemed to be a little too much emphasis on decentralized systems and anonymous file sharing. A few chapters appear to focus on broad topics but actually focus on the particular author's project. For Example, the security chapter was more or less an overview of grove networks. Another characteristic of this text is the fact that its basically 19 separate papers rolled in to one book so don't expect it to flow.
December 13, 2001

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