Using heuristics to improve service portfolio selection in P2P grids

In this paper we consider a peer-to-peer grid system which provides multiple services to its users. An incentive mechanism promotes collaboration among peers. It has been shown that the use of a reciprocation-based incentive mechanism in such a system prevents free-riding and, at the same time, promotes the clustering of peers that have mutually profitable interactions. On the other hand, an issue that has not been sufficiently studied in this context is that of service portfolio selection. Normally, peers are subject to resource limitations, which force them to provide only a subset of all services that can be possibly provided. Clearly, the subset of selected services impacts the profit that the grid yields to the peers, since each service will have a different cost and will return a different utility. Moreover, the utility generated by a service is strongly influenced by the behavior of the other peers, which in turn may change over time. In this paper we explore the use of heuristics to select the portfolio of services to be offered by peers in such a grid. The main contributions of this work are the use of heuristics to improve the average profit of peers and a study on the impact of some system characteristics on the heuristics behavior.