Abstract
As a result of a lack in a fair exchange mechanism for current Peer-to-Peer computing (P2P) systems, unfair exchange situation among peers, the existence of free-rider, tragedy of the commons, and non-cooperation hinders massive kinds of valuable resources to be effectively used as possible. A fair exchange mechanism for P2P systems is presented in this paper. Main idea is that, peer is firstly supposed to select their visiting peers which are always of good performance to access their local resources or to provide them with services they request. And secondly, visiting peers are classified according to the types of service and their priorities are decided in accordance with the quantity and quality of services they provided. Thirdly, a kind of electronic coupon as a proof of access to resources is designed, the number of which transferred between peers is adjusted by the priority of peers. The proposed fair exchange mechanism mainly consists of system initialization, peer access control, service priority adjustment, access to resources, and electronic coupon transfer. In order to tap the potential ability of P2P computing, the mechanism makes peers have no choice but to contribute their own resources actively and steadily, which not only guarantees the equity of interaction between peers, but also changes the fact that only a small number of peers contribute to the most quo of resources and services.