Design And Implementation Of Survivable Information Service Systems And Research Of Evaluation Method

With the development of computer science and network technology, society is now increasingly dependent upon large-scale, highly distributed systems that operate in unbounded network environments. Such dependency makes all the pivotal departments, such as the government and the army, can not afford the loss when the computer systems can't run normally. The discipline of survivability can help ensure that such systems can deliver essential services and maintain essential properties despite the presence of intrusions. This dissertation is in the context of building of CCERT content distribution website for CERNET. A survivable information service system has been designed and implemented, and an evaluation method called SEM for survivable systems has been described. The main three contributions of this dissertation are:1. The studying and summarization of the survivability theory.2. Designing and implementation of a survivable information service system through the survivable system design methods such as the layered control method and the reconfiguration method. Using three mechanisms, which are substitute mechanism, mutuality mechanism and assistance mechanism, we have resolved the one point invalidation problem, security information distribution not in time, heavy loading problem when the security affairs happen, etc. We used the non-local copies of information resources and the diversity strategies during the system designing and implementation, and the survivability of the system has been notably increased.3. Presentation an evaluation method for survivable systems called SEM, which is based on the Markov chain, MDPs model, and CMDPs model. The SEM method partitions the relatively steady states of the systems, concerns the abilities of the systems supplying the essential services, presents the survivability function and the six steps survivability evaluation process. We evaluate and analyze an instance information service system with SEM method in the end, and give some amelioration strategies to increase the system survivability.The information service system has achieved the goals of increasing the system survivability by using the P2P technology and the three mechanisms. The SEM method can be used to evaluate the special kind of systems with rather simple evaluation process. And the result can reflect the survivability state of the given system. The research achievements of this dissertation have been applied in the 863 items "Research of Collaborative Emergent Response and Excursion Based Survivable Systems" (2003AA142080), and it has laid a solid foundation for the smooth promotion of this 863 item.