Reducing the subscription latency in reliable causal publish-subscribe systems

Publish-subscribe systems are a powerful abstraction to build distributed applications. This paper addresses the problem of reducing subscription latency in reliable publish-subscribe systems. In most systems that offer reliability guarantees, a subscriber needs to wait until its subscription has been propagated throughout the entire system, and known by all relevant publishers, before starting to receive events. Interestingly, this may happen even when a previously deployed subscription covers a new one. In this paper, we study the properties that need to be satisfied to reduce the subscription latency and propose a new publish-subscribe system that leverages causal order multicast to offer low subscription latency when these conditions are met.