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A Directory of Peer-to-Peer Projects

by David Sims

In putting together this directory of companies in the peer-to-peer space, the editors at the O'Reilly Network spent some time debating whether many of them were truly peer-to-peer. Having ridden the Internet buzzword train for many years, we've watched as companies spin to re-label themselves: Netcos became Push companies, became B2B companies, became Open Source companies, and now, many are redefining themselves as peer-to-peer companies.

In some cases, the new label is valid: the company or project's efforts shift focus, or they merely see their efforts in a new light as broader paradigms are revealed. But we spent some time weighing these and discussing whether they should be included in a peer-to-peer directory.

For example, many of these companies are actually developing distributed computing applications, where a central organization takes advantage of the available cycles on thousands of PCs (nodes, if you will), and aggregates the data. By almost any definition, this can hardly be defined as peer-to-peer, since the peers cannot communicate with one another, but only with a central point. Sounds more like client-server.

And yet, the technical issues that these distributed computing projects face are similar to those faced by peer-to-peer projects. Both are faced with developing systems that coordinate the activities (or data) on thousands of external nodes. Also, both types of systems raise the once anonymous PC to the level of contributor to a larger effort, whether they are contributing a file (in the case of a file-sharing service like Freenet) or cycles (in the case of a distributed computing effort such as SETI@Home).

Tim O'Reilly, who got dragged into this discussion when he walked past my desk, says he sees at least three types of projects working in this peer-to-peer space:

As you can easily see, any of these types of applications could (and often do) work with a central server. But the field is just emerging to prominence and as the technology behind the less centralized efforts The P2P Directory (like Freenet) develops, we may find that even the centralized services, become more truly peer-to-peer.

With that, here's our Peer-to-Peer Directory. If you have thoughts about whether these companies belong, or you know of other efforts that should be included, visit our Forum and tell us about it.

David Sims was the editorial director of the O'Reilly Network.

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