The Internet is currently being used to support increasingly complex interactions. The entities, with which applications and services need to interact, span a wide spectrum that includes desktops, PDAs, appliances, and other networked resources. Clients - which abstract users, resources and proxies thereto - within these systems communicate with each other through the exchange of events, which are essentially messages with timestamps. In this paper we explore matching, routing and network utilization issues in the context of our research prototype NaradaBrokering, which provides support for centralized, distributed and P2P interactions.