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Niu J.,Tongji University | Niu J.,Embedded System and Service Computing Key Laboratory of Ministry of Education | Niu J.,China Institute of Technology | Zeng G.-S.,Tongji University | And 3 more authors.
Jisuanji Xuebao/Chinese Journal of Computers | Year: 2010

It has been a research focus that the performance analysis of complex systems such as network protocols which include nondeterministic choices. Besides time, space aspect is also considered during the process of performance evaluation. By model checking, we can verify whether time or space performance meets expected constraints. The authors adopt CTMRP (Continuous-Time Markov Reward Process) as the verification model since it can depict nondeterminism intuitively. The temporal logic CSRL (Continuous Stochastic Reward Logic) is extended by replacing path operators with regular expressions in order to express more comprehensive time or spatial properties which are based on states or paths. For deterministic schedulers, a duality result of constrained reachability probabilities between time and space is proposed, and its correctness is proved based on the existing work. Based on the theoretical consequences, the verification of space performance is reduced to the corresponding analysis of time reachability. The model checking algorithm and a new approach for the performance evaluation of complex systems are given.


Xu H.,Tongji University | Xu H.,East China Institute of Technology | Xu H.,Embedded System and Service Computing Key Laboratory of Ministry of Education | Zeng G.,Tongji University | And 3 more authors.
Journal of Software | Year: 2010

Continuing growth and increasing complexity of distributed software systems make them be more flexible, adaptive and easily extensible. Dynamic evolution or reconfiguration of distributed software systems is one possible solution to meet these demands. However, there are some challenges for building dynamically evolving distributed software systems at runtime, where dynamic software architectures for them is one of the most crucial problems. In this paper, we proposed a formal method of describing and verifying dynamic software architectures for distributed systems using hypergraph grammars. We firstly gave out reconfiguration production rules and operations for software architectures based on hypergraph grammars, and then described dynamic reconfiguration of software architectures for distributed systems according to those rules. At last we verified the invariant property of dynamic software architectures for those systems using model checking, and gave out corresponding verification algorithms. © 2010 ACADEMY PUBLISHER.

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