Broadcast Protocol Guaranteeing Causal Delivery Order Consistency Condition for Social Networks

Abstract

The social networks are based on sensor networks by mobile phones where social applications, such as real-time collaborative video watching applications, work out well, sensing their events collaboratively and socially. Recently, these networks use a contentbased distributed P/S (publish/subscribe) infrastructure that acts as a scalable group communication backbone. P/S based gossip protocols is elastically to scale in and out and provides suitable consistency guarantees for data safety and high availability but, does not deal with end-to-end message delay and message order-based consistency, which are addressed in real-time collaborative applications. Especially in broadcasting in real-time collaboration applications, it is possible for the messages to take different time and arrive at end users in different order. So, these applications should be based on P/S infrastructure including dealing with message timeliness and message ordering consistencies. Gossip communication is becoming one of the promising solutions for addressing P/S scalability problems in providing information propagation functionality by exploiting a mixture of diverse consistency options. In this paper, we present deadline-constraints causal order protocol respecting Δ(lifetime) based on P/S architecture for broadcasting in real-time collaborative applications in social networks to guarantee causally ordered messages delivery from brokers to subscribers. In the proposed protocol, every broker manages a 2dimensional vector, representing its knowledge of the last message sent by each broker at time t. But, every broker disseminates a broadcast message only with one scalar variable, the time-stamped information that represents the maximum gossip round and is the deadline (lifetime) of the immediate message of it, to subscribers because all messages disseminated by brokers have the same lifetime as the maximum number of gossip rounds. Therefore, the proposed protocol implemented for P/S based on gossip protocols results in very low communication overhead from brokers to subscribers in the context of broadcast respecting Δ.