A trust-aware,self-organizing system for large-scale federations of utility computing infrastructures

On-demand computing environments, like Cloud/Grid systems, consist of nodes that individually manage local resources intended to be served to clients. When a client needs some resources, it has the problem of finding the most suitable nodes capable of providing them. In addition, a provider node too may be in need to efficiently locate resources for itself, given the emerging, highly competitive, context of large-scale federations. Indeed, a node competes, with the other federated ones, to obtain the assignment of available tasks. To this end, it may decide to publish a set of resources/ services wider than the one it has currently available. Should such a node be assigned a job for which its actual resources are insufficient, it could end up requiring the collaboration of other nodes.Hence the crucial problem, for nodes and clients alike, is to determine the most promising collaborators. For this purpose, in the competitive and demanding scenarios considered, we advocate taking into account the trustworthiness of nodes in declaring their capabilities, i.e., to help it making an effective selection of possible collaborators, each node should be provided with a trust model for accurately evaluating the trustworthiness of its interlocutors.In this paper, a trust-based approach for large-scale federations Utility Computing infrastructures is proposed. The proposed model is designed to allow any node to find the most suitable collaborators in an efficient way, avoiding exploration of the whole node space. A fully decentralized approach is employed, which allows nodes of a federation to be organized in an overlay network on the basis of suitable criteria. This enables any customer or provider in need of collaborators to determine a suitable set of candidate nodes within which to search.