Managing reputation in contract-based distributed systems

In industry practice, bilateral agreements are established between providers and consumers of services in order to regulate their business relationships. In particular, Quality of Service (QoS) requirements are specified in those agreements in the form of legally binding contracts named Service Level Agreements (SLA). Meeting SLAs allows providers to be seen in the eyes of their clients, credible, reliable, and trustworthy. This contributes to augment their reputation that can be considered an important and competitive advantage for creating potentially new business opportunities. In this paper we describe the design and evaluation of a framework that can be used for dynamically computing the reputation of a service provider as specified into SLAs. Specifically, our framework evaluates the reputation by taking into account two principal factors; namely, the run time behaviors of the providers within a specific service provision relationship, and the reputation of the providers in the rest of the system. A feedback-based approach is used to assess these two factors: through it consumers express a vote on the providers' behavior according to the actions the providers undertake. We have carried out an evaluation that aimed at showing the feasibility of our approach. This paper discusses the principal results we have obtained by this evaluation. © Springer-Verlag 2009.