Introduction

Modern computing technologies have decentralized data processing power in an unprecedented manner. An important implication is that user machines, be it a desktop computer or a handheld PDA (personal digital assistant), have data processing power, in terms of instruction processing rate, amount of storage, and reliability, that was inconceivable merely a decade or two ago. Indeed, computing now occurs largely at the “edge” of networks. Network infrastructure systems have also made tremendous strides thanks to the ever improving communications technologies. Advancements in computing and communication, coupled together, enable a recent trend in a new form of distributed processing-peer-to-peer (P2P) computing [Oram, 2001,Steinmetz and Wehrle, 2005,Leuf, 2002,Minar and Hedlund, 2001,Milojicic et al., 2002, Roussopoulos et al., 2004, Schoder and Fischbach, 2003, Smith et al., 2003].