TERA: Topic-based event routing for peer-to-peer architectures

The completely decoupled interaction model offered by the publish/subscribe communication paradigm perfectly suits the interoperability needs of todays large-scale, dynamic, peer-to-peer applications. The unmanaged environments, where these applications are expected to work, pose a series of problems (potentially wide number of partipants, low-reliability of nodes, absence of a centralized authority, etc.) that severely limit the scalability of existing approaches which were originally thought for supporting distributed applications built on the top of static and managed environments. In this paper we propose an architecture for implementing the topic-based publish/subscribe paradigm in large scale peer-to-peer systems. The architecture is based on clustering peers subscribed to the same topic. The major novelty of this architecture lies in the mechanism employed to bring events from the publisher to the cluster (namely outer-cluster routing). The evaluation shows that this mechanism for outer-cluster routing has a probability to bring events to the destination cluster very close to 1 while keeping small the involved number of out-of-cluster peers. Finally, the overall architecture is shown to be scalable along several fundamental dimensions like number of participants, subscriptions, and to exhibit a fair load distribution (load distribution closely follows the distribution of subscriptions on nodes). © 2007 ACM.