What is eMule

Cooperation incentives have been proposed as an effective solution to various problems that plague Peer-to-Peer (P2P) and Computational Grid systems including: free-riding, resource discovery, collusion of resources, scalability and fairness. In this chapter we will introduce the concept of cooperation incentives and discuss their design goals and capabilities and how can they improve the characteristics of P2P systems. We will classify incentive mechanisms based on their pattern into four categories: trust-based, reputation-based, barter-trade and bond-based. These categories have different feature sets and can be applied to different scenarios, something we will elaborate on in this chapter. We will also discuss two very popular P2P file sharing systems: BitTorrent and eDonkey2000 (ED2K). We will use this discussion to illustrate how incentive mechanisms have been integrated into these widely-deployed very-successful P2P networks. Throughout our discussion, we will map incentive mechanisms proposed for P2P networks and Computational Grids to their well-established roots in economic systems and game theory.