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Keywords:

  • self-adaptive software;
  • goal-driven model;
  • run-time action selection

SUMMARY

Self-adaptive software is a closed-loop system, since it continuously monitors its context (i.e. environment) and/or self (i.e. software entities) in order to adapt itself properly to changes. We believe that representing adaptation goals explicitly and tracing them at run-time are helpful in decision making for adaptation. While goal-driven models are used in requirements engineering, they have not been utilized systematically yet for run-time adaptation. To address this research gap, this article focuses on the deciding process in self-adaptive software, and proposes the Goal-Action-Attribute Model (GAAM). An action selection mechanism, based on cooperative decision making, is also proposed that uses GAAM to select the appropriate adaptation action(s). The emphasis is on building a light-weight and scalable run-time model which needs less design and tuning effort comparing with a typical rule-based approach. The GAAM and action selection mechanism are evaluated using a set of experiments on a simulated multi-tier enterprise application, and two sample ordinal and cardinal action preference lists. The evaluation is accomplished based on a systematic design of experiment and a detailed statistical analysis in order to investigate several research questions. The findings are promising, considering the obtained results, and other impacts of the approach on engineering self-adaptive software. Although, one case study is not enough to generalize the findings, and the proposed mechanism does not always outperform a typical rule-based approach, less effort, scalability, and flexibility of GAAM are remarkable. Copyright © 2011 John Wiley & Sons, Ltd.