The 'Art' of Programming Gossip-based Systems

International audience; How does one best go about building actual gossip-based protocols? Trying to answer this question has brought us to address two preliminary questions, namely (1) what the in- trinsics of such systems or protocols are, and (2) what kind of applications would in the end be built on top of such protocols. We address the first question by arguing that gossip-based protocols are all built following one and the same pattern, and describing three building blocks which we claim are used to support this recurrent pattern—most notably a source of randomness. We validate these claims by devising simplified versions of well-known protocols, in a layered fashion, on top of a conceptual interface describing these basic services. The second question is addressed by ar- guing that gossip-based protocols exhibit some probabilistic or imperfect flavor (e.g., probabilistic or partial completion), and by proposing to take such probabilistic behavior into ac- count when devising interfaces for applications building on top of gossip-based protocols. We argue for inherent support for these probabilities in the programming model.