Queue reorganization for subscription congestion avoidance in publish/subscribe systems

Content-based publish/subscribe systems allow subscribers to specify interests based on event contents, rather than pre-assigned event topics. Since most of existing publish/subscribe systems use FIFO (First In First Out) as its queue management mechanism, it may face network congestion coming from suddenly burst of huge amount of subscription messages as well as event notifications. To promote the ability to handle congestion challenge, we present a new queue management mechanism called queue reorganization algorithm. By taking advantage of similarities among concurrent subscriptions, queue reorganization algorithm can make covering subscriptions as proxies and remove unnecessary subscriptions at each broker, which in turn greatly reduces pressure from congested input queue. Detailed evaluations under various workloads show significant benefits of the optimizations in terms of input queue size and message routing cost.