Reconfiguring Publish/Subscribe Overlay Topologies

Distributed content-based publish/subscribe systems are usually implemented by a set of brokers forming an overlay network. Most existing publish/subscribe middleware assumes that the overlay topology is static. Those that consider reconfiguration, exchange a single link that is torn down by another link that comes up. However, they do not guarantee that no notifications are lost or duplicated nor do they ensure any message ordering policy. In this paper, we discuss the dynamic reconfiguration of publish/subscribe systems which are built on content-based routing. We present algorithms that allow for reconfigurations without notification loss or duplication that can also ensure FIFO-publisher and causal ordering. Moreover, the efficiency of reconfigurations is increased by limiting their effects to those parts of the network which are directly affected by the reconfiguration.