The subscription-cover based routing algorithm in content-based publish/subscribe

Subscription-cover relationship has been proposed to reduce the size of routing-table in intermediate brokers in the publish/subscribe network. Existing researches neglect the extent that covering can be applied and don't give a simple approach to validate the correctness of routing-table when using subscription-cover. In this paper, we propose two routing algorithms based on subscription-cover, which are strict subscription-cover based routing (SSCBR) and relaxed subscription-cover based routing (RSCBR). The goal of the former is to maintain the least covered subscriptions. The latter maintains more covered subscriptions to balance in memory, time and network traffic. On the other hand, we propose a necessary and sufficient condition of correct routing-table configuration when applying SSCBR. We can easily validate the correctness of broker's routing-table through it. Experiments evaluate the ability of two algorithms in reducing the routing-table size of intermediate broker and the efficiency of SSCBR and RSCBR under different subscribing/unsubscribing distribution.