Concepts and Models of Environment of Self-Adaptive Systems: A Systematic Literature Review

The runtime environment is an important concern for self-adaptive systems (SASs). Although researchers have proposed many approaches for developing SASs that address the issues from runtime environments, the understanding of these environments varies depending on the objectives, perspectives, and assumptions of the research. Thus, the current understanding of environments in SAS development remains ambiguous and abstract. To make this knowledge more concrete, we investigated concepts and models of the environment covered in this area through a systematic literature review (SLR). We automatically and manually searched 3719 papers and selected 128 papers as primary studies. We explored and analyzed concepts of the environment covered in the primary studies and investigated cases in which the concepts were specifically expressed as environment models. In doing so, we provide trends of how SAS academia understands the environment of SAS. Specifically, this SLR provides five common characteristics of the environment, two common sources of the environmental uncertainty, and 14 reference environment models with various purpose and expressiveness. Finally, we summarized lessons learned through this SLR and directions for future SAS research on the basis of the concrete knowledge of the SAS environment.