中文摘要：

提出了基于内容发布／订阅系统的一种准入控制机制RacsCBPS来保障客户端的服务质量．首先分析了基于内容发布／订阅系统中实现准入控制机制的难点，给出了RacsCBPS的基本模型，在此基础上，提出了基于覆盖关系的资源需求计算方法和以订阅分发路径为基础的准入控制算法．RacsCBPS在不影响发布／订阅系统松散耦合性的情况下，能够有效地解决因系统资源不足而导致的事件过载问题，同时为系统提供了不同的准入准则，以便在系统资源利用率和服务质量保证程度之间作出不同的权衡．最后通过实验验证了准入控制机制的有效性和相应的系统资源利用率．

英文摘要：

This paper presents RacsCBPS, an admission control scheme for large-scale and scalable content-based publish/subscribe systems. First the key requirements to implement admission control in content-based publish/subscribe systems are identified and how it differs from admission control schemes in the Internet and other research areas is analyzed. A cover-relation based algorithm to compute subscription resource requirements and an admission control algorithm based on subscription routing are presented. The scheme ensures time, space and control decoupling without sacrificing scalability of publish/subscribe systems. Publish/Subscribe systems can seek different balances between system resource utilization and QoS guarantee by choosing different admission control criteria. Experimental results show the effectiveness of the method.