Dragon: Multidimensional Range Queries on Distributed Aggregation Trees,

Distributed query processing is of paramount importance in next-generation distribution services, such as Internet of Things (IoT) and cyber-physical systems. Even if several multi-attribute range queries supports have been proposed for peer-to-peer systems, these solutions must be rethought to fully meet the requirements of new computational paradigms for IoT, like fog computing. This paper proposes dragon, an ecient support for distributed multi-dimensional range query processing targeting ecient query resolution on highly dynamic data. In dragon nodes at the edges of the network collect and publish multi-dimensional data. The nodes collectively manage an aggregation tree storing data digests which are then exploited, when resolving queries, to prune the sub-trees containing few or no relevant matches. Multi-attribute queries are managed by linearising the attribute space through space lling curves. We extensively analysed dierent aggregation and query resolution strategies in a wide spectrum of experimental set-ups. We show that dragon manages eciently fast changing data values. Further, we show that dragon resolves queries by contacting a lower number of nodes when compared to a similar approach in the state of the art

Analisi e valutazione di algoritmi distribuiti per la costruzione della Triangolazione di Delaunay

Delaunay triangulations are very useful because of their mathematical properties, expolited in several distributed applications, from peer-to-peer networks to sensor and geographical networks. For these reasons, several distributed algorithms for the construction of Delaunay based overlays have been recently proposed. This thesis presents a survey of the main distributed algorithms for the construction of the Delaunay Triangulation presented in the last years, and of their applications, with particular focus on the innovative techniques. The analysis has led to the definition of NewACE, a new distributed algorithm, which has been compared with two state of art approahes. The thesis presents a set of experimental results showing the pro and the cons of these algorithms