Design and evaluation of a wide-area event notification service

Reviewer: Klaus Galensa

Event notification systems deliver information sent by event publishers to clients who have subscribed to that information. Event notification underlies such now-popular applications as “instant messenger” and stock price tracking services. An event notification service (ENS) is an application-independent infrastructure that supports the construction of event-based systems. Most ENSs are based on a centralized server, and therefore do not scale well in wide-area networks like the Internet. In this paper, the authors present a scalable ENS, called SIENA, which they have designed and implemented. First, the scaling problem and the chosen solution are outlined. Then, SIENA’s application programming interface is introduced. A presentation of several server topologies and protocols is followed by a description of the routing algorithms used by the service to deliver event notifications. The authors discuss strategies for optimizing the performance of the notification selection process. Supported in part by the results of simulation studies, the scalability of the design choices is analyzed. Before concluding the paper, the authors discuss related work and future plans. The main focus of this well-structured and very readable research paper is on the notification selection process, and on the scalability of the delivery service. Other design criteria, like resilience in the presence of broken links, administration of the service, and security, are outside the scope of this paper. A discussion of those topics can be found in Cabrera, Jones and Theimer [1]. Unfortunately, the authors did not cite this paper. Online Computing Reviews Service