To reduce the negative impact of the inherent time lag property of trust evaluation on the result of evaluation, new time lag weakening policies for enhancing trust evaluation reliability were proposed by integrating the trust trends of target entity into trust evaluation process with second derivative as the measurement tool. In order to check the effectiveness of this strategy, with the idea of reverse engineering, the authors used it to extend the famous trust revaluation model proposed by Srivatsa. The results show the parts of trust evaluation result with the extended model is closer to the real behavior of the target entity than that of the original model, and the former is more capable of inhibiting the fluctuating behavior of malicious entity. All of these indicate that the time lag weakening policies can be used to enhance the reliability of trust evaluation.

Current survivability models can hardly bring up a practical solution, nor reflect the properties of Web applications. Firstly, the properties of Web applications were analyzed, especially the differences between atomic Web applications and composite Web applications. Secondly, the mathematical model reflecting the invoking relationship of the atomic Web applications for the development of composite Web application was constructed. Lastly, a survivability model for atomic Web applications and a Markov-based survivability model for composite Web applications with regard to runtime environment were proposed. And on the basis of these models, a recovery approach for Web applications was given, when part or all of the functions failed in adverse environment. Besides, a case was analyzed using these models, and its recovery procedures were given, in which the high survivability was guaranteed.

The cooperative rollback recovery mechanism based on checkpointing is an effective mechanism for the survivability of distributed system. The existing cooperative rollback recovery mechanism based on checkpointing presumes that the communication channel is reliable. However, this assumption is not always true in actual application scenarios. For the actual application scenarios of distributed system, a reliable assurance model for the survivability of distributed system was proposed, based on the checkpointing-based rollback recovery mechanism. Through the creation of redundant communication channel and process migration mechanism, the proposed model assures the survivability of distributed system in actual application scenarios where the communication channel is not reliable.

The efficiency of packet filter is vital for firewalls.An efficient packet filter solution based on INTEL IXP2400 was talked about.This solution optimized packet filter through dynamic rule table,static rule tree and hardware hash unit.The firewall designed in this way can reach 1000M line speed.