tailieunhanh - Design and Evaluation of a Wide-Area Event Notification Service

The components of a loosely coupled system are typically designed to operate by generating and responding to asynchronous events. An event notification service is an application-independent in- frastructure that supports the construction of event-based systems, whereby generators of events publish event notifications to the infrastructure and consumers of events subscribe with the infras- tructure to receive relevant notifications. The two primary services that should be provided to com- ponents by the infrastructure are notification selection (., determining which notifications match which subscriptions) and notification delivery (., routing matching notifications from publishers to subscribers). Numerous event notification services have been developed for local-area networks, generally based on a centralized. | Design and Evaluation of a Wide-Area Event Notification Service ANTONIO CARZANIGA University of Colorado at Boulder DAVID S. ROSENBLUM University of California Irvine and ALEXANDER L. WOLF University of Colorado at Boulder The components of a loosely coupled system are typically designed to operate by generating and responding to asynchronous events. An event notification service is an application-independent infrastructure that supports the construction of event-based systems whereby generators of events publish event notifications to the infrastructure and consumers of events subscribe with the infrastructure to receive relevant notifications. The two primary services that should be provided to components by the infrastructure are notification selection . determining which notifications match which subscriptions and notification delivery . routing matching notifications from publishers to subscribers . Numerous event notification services have been developed for local-area networks generally based on a centralized server to select and deliver event notifications. Therefore they suffer from an inherent inability to scale to wide-area networks such as the Internet where the number and physical distribution of the service s clients can quickly overwhelm a centralized solution. The critical challenge in the setting of a wide-area network is to maximize the expressiveness in the selection mechanism without sacrificing scalability in the delivery mechanism. This paper presents Siena an event notification service that we have designed and implemented to exhibit both expressiveness and scalability. We describe the service s interface to applications the algorithms used by networks of servers to select and deliver event notifications and the strategies used Effort sponsored by the Defense Advanced Research Projects Agency and Air Force Research Laboratory Air Force Materiel Command USAF under agreement numbers F30602-94-C-0253 F30602-97-2-0021 F30602-98-2-0163 .