We address the problem of content-based dissemination of highly-distributed, high-volume data streams for stream-based monitoring applications and large-scale data delivery. Existing content-based dissemination approaches commonly rely on distributed filtering trees that require filtering at all brokers on the tree. We present a new semantic multicast approach that eliminates the need for content-based filtering at interior brokers and facilitates fine-grained control over the construction of efficient dissemination trees. The central idea is to split the incoming data streams (based on their contents, rates, and destinations) and then spread the pieces across multiple channels, each of which is implemented as an independent dissemination tree. We present the basic design and evaluation of SemCast, an overlay-network based system that implements this semantic multicast approach. Through a detailed simulation study and realistic network topologies, we demonstrate that SemCast significantly improves the efficiency of dissemination compared to traditional approaches. 1.

Application-level content-based routing using XML is a key technology for decentralized publish / subscribe systems. In this paper, a new approach is proposed to support the efficient dissemination of XML packets when allowing the clients to specify their subscriptions with path queries. The proposed method is based on Chord-liked distributed hash table (DHT) scheme. The integration of XML packet filtering and finger table based routing in structured overlay networks provides an elegant base for the proposed SONNET system, upon which the optimization techniques are studied. Analytical and empirical results have shown that the coupling of disseminating and routing in publish/subscribe systems could offer robustness and extensibility for the systems, while the decoupling of the two aspects brings more scalability and workload balance. Extensive empirical studies have demonstrated that the proposed method outperforms previous efforts for content-based routing.