Section: Overall Objectives

Scalability: Cloud computing meets p2p

Our second objective is to move forward in the area of scalable infrastructures for data intensive applications. In this context, we focus significant efforts on personalization systems, which represent one of the biggest challenges addressed by most large stake holders.

Hybrid infrastructures for personalisation. So far, social filtering techniques have mainly been implemented on centralized architectures relying on smart heuristics to cope with an increasing load of information. We argue however that, no matter how smart these heuristics and how powerful the underlying machines running them, a fully centralized approach might not be able to cope with the exponential growth of the Internet and, even if it does, the price to be paid might simply not be acceptable for its users (privacy, ecological footprint, etc.).

At the other end of the spectrum, lie fully decentralized systems where the collaborative filtering system is implemented by the machines of the users themselves. Such approaches are appealing for both scalability and privacy reasons. With respect to scalability, storage and computational units naturally grow with the number of users. Furthermore, a p2p system provides an energy-friendly environment where every user can feel responsible for the ecological foot-print of her exploration of the Internet. With respect to privacy, users are responsible for the management of their own profiles. Potential privacy threats therefore do not come from a big-brother but may still arise due to the presence of other users.

We have a strong experience in devising and experimenting with such kinds of p2p systems for various forms of personalization. More specifically, we have shown that personalization can be effective while maintaining a reasonable level of privacy. Nevertheless, frequent connections/disconnections of users make such systems difficult to maintain while addressing privacy attacks. For this reason, we also plan to explore hybrid approaches where the social filtering is performed by the users themselves, as in a p2p manner, whereas the management of connections-disconnections, including authentication, is managed through a server-based architecture. In particular, we plan to explore the trade-off between the quality of the personalization process, its efficiency and the privacy guarantees.