äPeers In A Client Server Worldô provides a comprehensive overview of emerging peer-to-peer (P2P) technologies that have revolutionized the way we think about distributed computing and the internet. These technologies are compared to alternative solutions, most notably web services and Grid computing but also other technologies, such as client/server based systems and agent technologies. A wide range of diverse middleware and application-based technologies are covered, such as JXTA, Jini, Globus, Web services, OGSA, J2EE, Napster and Gnutella, with an emphasis given on the architecture employed and security model chosen. Each technology and its capabilities are analyzed in the context of the degree of centralization or decentralization they employ. A resulting taxonomy is created that gives the reader a context in which to consider the most advanced and broad ranging distributed systems available today, and provides them with an essential reference text for designing new distributed systems.