Update propagation for peer-to-peer-based massively multi-user virtual environments

Over the last decade Massively Multi-user Virtual Environments (MMVEs) have become an integral part of modern culture and business. Applications for these large-scale virtual environments range from gaming to business and scientific research. Some MMVEs reach a user base in the tens of millions and the total number of users is estimated in the billions. Despite this success, launching an MMVEs is still a risky proposition. This is in large part due to the high cost associated with setting up and maintaining the necessary server infrastructure. One way of reducing the costs of operating MMVEs is to switch their system architecture from the current client/server-based model to one based on peer-to-peer (P2P) technologies. This has the potential to significantly reduce the infrastructure costs of MMVEs, as users bring their own resources into the P2P system and servers are no longer required, thus decreasing expenses and market entry barriers. This thesis describes a scalable and low-latency update propagation system for P2P-based MMVEs. Update propagation refers to the exchange of information about changes in the virtual environment between users and is one of the key components of MMVEs. Thus, the described system represents a key step towards operating MMVEs as fully distributed peer-to-peer systems

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