Kwok presents a thin though comprehensive monograph on the current state of peer-to-peer (P2P) research. Certain omissions are glaring, but by and large the treatment of the topic is extensive. A researcher or graduate student who would like to get up to speed on the state of the art in P2P networks will most certainly benefit from this monograph.

It is divided into eight chapters, with the first three devoted to the background needed to be conversant in this sub-field (structured versus unstructured networks, distributed hash tables, and so on). The last chapter is a short conclusion, so that leaves four chapters to tackle the existing P2P literature in the following areas: topology control, incentives, trust, and security issues. The treatment of each topic is extensive, and a case study on PPLive is maintained as a running thread at the end of each chapter. That said, there are certain omissions, the inclusion of which would have made the monograph more complete.

To wit, there is extensive and recent literature on P2P localization techniques, and standardization work in the Internet Engineering Task Force (IETF), aimed at developing a protocol that will allow peers to make intelligent choices when deciding which other peer to contact for resource sharing. The author briefly touches on this, but does not explore it fully; instead, he chooses to couch the debate in terms of quality of service (QoS). There is much focus on QoS in the monograph, but I am not convinced that the lack of QoS is the hindering factor for P2P. Similarly, trust is an important feature in P2P networks; while there is much academic work on this topic, it illustrates that most of the P2P networks operating today (including PPLive) operate on the best faith of the peers involved. It would have been good to survey some literature on private trackers and how the issue of trust is handled in that closed community. Finally, the running case study of PPLive is a bit lightweight. More details on it could have been provided.

In sum, this is a good monograph for getting up to speed on the main issues surrounding P2P networks and for catching up with the extensive literature in this area.