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Runtime Analysis of Self-adaptive Systems

Bagheri, Maryam | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54065 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Movaghar, Ali; Sirjani, Marjan
  7. Abstract:
  8. Increasing the complexity of software systems, their ubiquitous presence in the human activities, and necessity to preserving the functional and nonfunctional requirements of the systems under an uncertain environment, increase the need for self-adaptive systems. A self-adaptive system changes its structure and behaviors in response to changes in its environment and the system itself. A key research challenge in the self-adaptive community is to guarantee that the system fulfills its requirements. This issue can be addressed by employing formal methods during the design of the software systems. However, the assurance techniques should be used during the execution of the system as well as the design time. To this end, maintaining a model of the system at runtime, updating it base on the changes in the system and its environment, and verifying the model are necessary tasks. The analysis results are used to make an adaptation decision for the system. Th focus of this research is on verifying self-adaptive systems, especially Track-based Traffic Control Systems (TTCSs), at runtime. To this end, a coordinated actor model is proposed. A fine-grained and a coarse-grained semantics for the coordinated actor model are proposed, and it is proved that the two semantics are in an action-based weak bisimulation relation. Then, the Magnifier technique, which is based on the compositional verification, is specially proposed for verifying self-adaptive TTCSs. The employed semantics in this technique is based on networks of Timed Automata. Furthermore, a compositional approach for partial order reduction of timed actors is proposed. Finally, a semantics for the robust planning of the moving objects in a TTCS is proposed. This thesis exploits the Ptolemy framework as an implementation platform. Ptolemy provides an actor-based modeling language to model and simulate cyber-physical systems. In this thesis, Ptolemy is extended with appropriate models of computation to generate the state space of a system
  9. Keywords:
  10. Actor Model ; Self-Adaptive System ; Verification ; Runtime Model ; Ptolemy Modeling Framework ; Air Traffic

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