中文摘要：

针对应用服务器组件和平台之间的老化依赖关系特征，提出了应用组件再生和应用服务器系统再生两个不同粒度的定时再生采略．通过建立应用服务器老化过程的半马尔科夫模型，获得了应用服务器的可用性和维护费用函数，分析了最优再生时间的边界条件，理论分析表明两级再生策略优于单级的再生策略。模拟实验显示的再生策略和原有的再生策略相比，不仅提高了应用服务器的可用性，同时降低了系统的维护费用。

英文摘要：

Aiming at the characteristic of the dependency relationship between the Application Server components and the platform, a rejuvenation strategy with two different levels of rejuvenation granularities was put forward including the application component rejuvenation and the Application Server system rejuvenation. The reliability and maintenance cost functions were obtained through establishing Semi-Markov Process of the Application Server aging process, and the boundary condition of the optimal rejuvenation time was analyzed. Theory analysis indicates that the two-level rejuvenation strategy is superior to the traditional single step one. Simulation experiments are carried out and results show that compared with the traditional rejuvenation policy, the rejuvenation strategy proposed can further increase availability of the Application Server and reduce download cost.