A DHT-based Infrastructure for Content-based Publish/Subscribe Services

Publish/subscribe model has become a prevalent paradigm for building distributed event delivering systems. Content-based publish/subscribe allows high expresses in subscriptions and thus is more appropriate for content dissemination. However, the scalability has remained a challenge in the design of distributed content-based publish/subscribe systems due to the expensive matching and delivering cost of content-based events. In this paper we propose an infrastructure built on top of distributed hash table for efficient content-based data distribution. Based on efficient subscription installation, event publication and event delivery mechanisms, the proposed infrastructure can simultaneously support any numbers of pub/sub schemas with different number of attributes. There are three key features in our design: (1) a locality-preserving hashing mechanism which partitions and maps the content space to nodes. Subscriptions and events are mapped to the corresponding node for efficiently matching; (2) an efficient event delivery algorithm which exploits the embedded trees in the underlying DHT to deliver events to the corresponding subscribers; (3) light-weighted load balancing mechanisms to adjust the load among peers and ensure that no peer is unduly loaded.