Cloud-assisted Dissemination in Social Overlays

Decentralized social networks are an emerging solution to the privacy issues plaguing mainstream centralized architectures. Social overlays---overlay networks mirroring the social relationships among node owners---are particularly intriguing, as they limit communication within one's friend circle. Previous work investigated efficient protocols for peer-to-peer (P2P) dissemination in social overlays, but also showed that the churn induced by users, combined with the topology constraints posed by these overlays, may yield unacceptable latency. In this paper, we combine P2P dissemination on the social overlay with occasional access to the cloud. When updates from a friend are not received for a long time, the cloud serves as an external channel to verify their presence. The latter acts as an external channel to check for friend updates, when these are not received for a long time. The outcome is disseminated in a P2P fashion, quenching cloud access from other nodes and, if an update exists, speeding dissemination. We show that our protocol performs close to mainstream centralized architectures and incurs only modest monetary costs.