ism: intent-perceptible service migration model for ip network survivability

由于传统的服务漂移方法存在一定不足,致使服务器集群的负担较重,且服务漂移的时间开销过大,严重影响服务连续性.为了改善这种情况,本文提出了一种漂移意图可感知的IP网络生存性服务提供模型(Inten-tper-ceived Service Migration,ISM).在ISM模型中,我们设计了一种独特的服务漂移触发机制和目标节点选取策略,并通过服务器与客户端的协作,使客户端对服务器集群内部的服务漂移意图有了预感知能力.分析结果表明,ISM模型既能在时间和空间上保证服务漂移的随机性,增强服务抗毁度;又能显著减小由服务漂移带来的服务间断时间,有效提高了IP网络服务可生存性.国家973计划课题(No.2007CB310706)|国家自然科学基金项目(No.60725104,No.60873263,No.60932005)|国家863计划课题(No.2009AA01Z215)|四川省青年基金项目(No.09ZQ026-032)|教育部新世纪优秀人才计划The existing service migration methods bring the server cluster heavy burden, and their time spending is so high that seriously affects the service continuity. In order to enhance the survivability of IP network services, the paper puts forward an intent-perceptible service migration model (ISM). In this model, we design a novel trigger mechanism and object selecting method for service migration, and make the service migration intention perceptible for the client with the cooperation of the server. The evaluation results show that ISM model can not only ensure the service invulnerability by maintaining a high randomness of service migration, but also improve the service continuity by reducing the service gap time spending on service migration to the maximum extent. Therefore, ISM model can enhance IP network survivability efficiently

Cloning,sited-directed mutagenesis and expresison of hCu,Zn-SOD gene in E.coli

目的　在克隆人源铜锌超氧化物歧化酶基因 (hCu ,Zn -SOD)的基础上 ,对hCu ,Zn -SOD进行定点突变 ,使其在E .coliDH5α中表达 ,为进一步改造hCu ,Zn -SOD基因奠定基础。方法　首先构建质粒 pESOD ,然后用定点突变技术把其中hCu ,Zn -SOD的Cys111密码子突变为Ala111密码子 ,再与 pUCMT1相连接 ,构建表达载体pE SODT111,使其在E .coliDH5α中表达 ,表达产物用改良的邻苯三酚法和Westem杂交测定。结果　hCu ,Zn -SOD突变后在E .coliDH5α中成功表达 ,表达产物具有SOD活性 ,活力为 16 4 4 7U/ml培养液。结论　hCu ,Zn -SOD基因经过定点突变后构建的表达载体可在DH5n中表达 ,表达产物同样具有天然的hCu ,Zn -SOD活性Objective For further researching of hCu,Zn-SOD gene engineering,to mutate human copper,zinc-superoxide dismutage gene(hCu,Zn-SOD),and expressed the plamid in E.coli DH5α.Methods The pESOD plamid was constructed firstly,then the Cys 111 genetic code of hCu,Zn-SOD gene in the pESOD plamid was mutated into the Ala 111 code with sited directed mutagenesis and the expression plamid pESODT111 was constructed by inserting the mutated pESOD into pUCMT1 plamid.The pESODT111 plamid was expressed in E.coli JM101.The expression product was determined by Western blot and improved by pyrogallol autoxidation. Results Mutated hCu,Zn-SOD gene expressed in E.coli DH5α correctly,the expression product had SOD activity-16.447?U/ml culture medium.Conclusion The expression product of the mutated hCu,Zn-SOD had activity of native hCu,Zn-SOD.国家自然科学基金 (40 2 0 60 1 8