Privacy and temporal aware allocation of data in decentralized online social networks

Distributed Online Social Networks (DOSNs) have recently been proposed to grant users more control over the data they share with the other users. Indeed, in contrast to centralized Online Social Networks (such as Facebook), DOSNs are not based on centralized storage services, because the contents shared by the users are stored on the devices of the users themselves. One of the main challenges in a DOSN comes from guaranteeing availability of the users' contents when the data owner disconnects from the network. In this paper, we focus our attention on data availability by proposing a distributed allocation strategy which takes into account both the privacy policies defined on the contents and the availability patterns (online/offline) of the users in order to allocate their contents on trusted nodes. A linear predictor is used to model and to predict the availability status of the users in a future time interval, on the basis of their past temporal behaviour. We conduct a set of experiments on a set of traces taken from Facebook. The results prove the effectiveness of our approach by showing high availability of users' profiles.