Overlay broker networks are an important part of an eventbased middleware. In this paper, we investigate the requirements of overlay broker networks and argue that using peer-to-peer techniques for their creation and the contentbased routing of events has many advantages. We support our claims with an experimental evaluation of Hermes, an event-based middleware architecture that uses a peer-topeer routing substrate, in comparison with a standard publish/subscribe system that has a simple, predefined overlay topology. The results reveal that Hermes has better routing efficiency and keeps less routing state at the event brokers. Keywords event-based middleware, overlay broker networks, contentbased routing, simulation, experimental evaluation
Peter R. Pietzuch, Jean Bacon