earticle

영어

In most large-scale distributed applications, publish/subscribe (P/S) systems allow a decoupling between senders and receivers to interact with publishers and subscribers. Recently, in these areas, there has been increasing emphasis in managing end-to-end message delivery performance and message order-based consistency, which have been addressed in distributed collaborative applications. Especially, a causally ordered delivery consistency is more useful for these applications in which a large number of processes request collaboratively and interactively. In P/S systems of wireless sensor networks (WSNs), data fusion, the process of correlating individual sensor readings into high-level sensing results, depends on a causally ordered delivery. And gossip protocols based on P/S systems are becoming one of the promising solutions for addressing P/S scalability problems and very useful for the applications with a mixture of diverse message order consistencies. In this paper, we present two versions of causally ordered delivery protocols based on P/S systems using gossip protocols. The one is that only the predecessors immediately before the multicast message are disseminated from brokers to subscribers. And the other, specifically for P/S systems of WSNs, is that the timestamps that represent the gossip round in which the immediate predecessors are generated are disseminated from brokers to subscribers. The features of these two versions might be highly scalable and suitable for the area of the applications requiring only the minimum causal information with flexible consistency.