From P2P to Web Services and Grids / Computer Communications and Networks (PDF)

9 Freenet (p. 151)

This chapter is dedicated to the Freenet distributed information storage system. Freenet was chosen to be included because it gives an excellent example of how many of the techniques discussed so far in this book can be adapted and used in a practical and innovative system. For example, Freenet works within a P2P environment (Chapter 2) and addresses the inherently untrustworthy and unreliable participants within such a network.

Freenet is self-organizing and incorporates a learning algorithm that allows the network to adapt its routing behaviour based on prior interactions. This algorithm is interestingly similar to social networking and achieves a power-law (centralized-decentralized) structure (discussed in Chapter 7) in a self-organizing manner. Such a technique o.ers a di.erent perspective on how to e.ciently scale P2P networks (e.g., Gnutella in Chapter 6) to hundred of thousands of nodes. Freenet was designed from the ground up to provide extensive protection from hostile attack, from both inside the network and out by addressing key information privacy issues. Freenet therefore implements various security strategies that maintain privacy for all participants, regardless of their particular role. The individual security techniques that are used collectively in Freenet were discussed in Chapter 8.

This chapter is concise but it provides a relevant real-world application that integrates many of the technologies described thus far. For a more detailed overview of Freenet see [58], [59] and [61].

9.1 Introduction

Freenet is a decentralized system for storing and retrieving files within a massively distributed network. Each Freenet participant provides some network storage space and acts as a servent (i.e., both clients and servers as in Gnutella), both providing storage and requesting it. Freenet di.ers in philosophy to Gnutella as it gives P2P participants write access to the distributed

From the reviews:

"Provides rich background information to beginners entering this subject area. … The diagrams … are clear-cut, as are the snippets of codes. There are hardly any errors throughout the book. … covers a broad and coherent range of distributed-computing techniques … . People with different programming abilities, even those who have never written a single line of code … learn a lot from it. … recommend the book to anyone interested in distributed computing, especially students in the field of distributed computing … ." (Haoyang Che, THE COMPUTER JOUNAL, Vol. 48(3), 2005)

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