Subscription tree pruning: A structure-independent routing optimization for general-purpose publish/subscribe systems.

A main challenge in distributed publish/subscribe systems is the efficient and scalable routing of incoming information (event messages). For largescale publish/subscribe services, subscription forwarding has been established as a prevalent routing scheme. It reduces the network traffic for event routing due to selectively forwarding event messages to relevant parts of the network only. To further improve event routing, publish/subscribe systems apply routing optimizations. So far, optimizations for general-purpose publish/subscribe systems are still missing. In this paper, we present the architecture, realization, and evaluation of our prototype of a large-scale publish/subscribe service applying a novel routing optimization, subscription tree pruning. We also show a comparison of five existing routing optimizations in respect to six important characteristic parameters affecting the suitability of these approaches in practice (including space usage, time efficiency (throughput), and network load). This comparative analysis clearly demonstrates the advantages of subscription pruning over other routing optimizations. In our practical experiments, we then investigate the behavior of our prototype regarding all quantitatively measurable parameters from our previously theoretically analyzed ones. Our evaluation of subscription pruning in this paper is more extensive than previous analyses of any routing optimizations for publish/ subscribe systems, which focus on selected parameters only