Peer-to-peer (P2P) computing promises to o?er exciting new possibilities in d- tributed information processing and database technologies. The realization of this promise lies fundamentally in the availability of enhanced services such as structured ways for classifying and registering shared information, veri?cation and certi?cation of information, content-distributed schemes and quality of c- tent, security features, information discovery and accessibility, interoperation and composition of active information services, and ?nally market-based me- anisms to allow cooperative and...