SCRIBE: A large-scale and decentralized publish-subscribe infrastructure

This paper presents Scribe, a large-scale event notification infrastructure for topic-based publishsubscribe applications. Scribe supports large numbers of topics, with a potentially large number of subscribers per topic. Scribe is built on top of Pastry, a generic peer-to-peer object location and routing substrate overlayed on the Internet, and leverages Pastry’s reliability, self-organization, and locality properties. Pastry is used to create a topic (group) and to build an efficient multicast tree for the dissemination of events within a topic with a potentially large set of subscribers (members). Scribe provides weak reliability guarantees, but we outline how an application can extend Scribe to provide stronger ones. Simulation results, based on a realistic network topology model, show that Scribe scales across a wide range of topics and subscribers per topic. Also, it balances the load on the nodes while achieving acceptable delay and link stress when compared to IP multicast.