Publish/Subscribe (pub/sub) is an important paradigm for distributed content delivery. Traditionally, there have been two approaches to supporting pub/sub service: subject-based and content-based. Content-based pub/sub allows fine-grained expressiveness, and thus is a more attractive solution for content dissemination. However, the performance of a content-based pub/sub network is bounded by the expensive matching cost of content messages. In this paper, we propose a hybrid approach capable of minimizing both the matching and forwarding overhead within the pub/sub network and the delay experienced by clients receiving the content. The hybrid approach aims to eliminate redundant matching and forwarding inside the pub/sub network. In particular, it identifies a number of virtual groups by exploring common subscription interests among clients, and messages for each virtual group are only matched once at the group entry point. In addition, for each virtual group, the content delivery tree embedded in the underlying pub/sub network can benefit from shortcutting forwarding-only paths. Simulations have shown that the hybrid approach is highly effective in improving the service efficiency and quality of a content-based pub/sub system
['Rongmei Zhang', 'Y.C. Hu']
HYPER: A Hybrid Approach to Efficient Content-Based Publish/Subscribe