Combining Goals and SysML for Traceability and Decision-Making in the Development of Adaptive Socio-Cyber-Physical Systems

Abstract

Socio-cyber-physical systems (SCPSs) are cyber-physical systems (CPSs) with a sociotechnical system (STS) aspect. Several SCPSs need to adapt dynamically to changing situations in order to reach an optimal symbiosis with users in their contexts. Tailoring requirements engineering activities and modeling techniques is needed for developing SCPSs and supporting their runtime adaptability. Goal models are used to support early requirements engineering activities by capturing system and stakeholder objectives and their links, and by enabling what-if and trade-off analysis in a decision-making context. They are also increasingly used in system monitoring and self-adaptation contexts. Yet, linking system models to goals and automatically converting goal models to code for supporting analysis and adaptation activities remain important issues. This thesis combines a common way of modeling STSs (i.e., goal modeling with the Goal-oriented Requirement Language – GRL) with a conventional way of modeling CPSs (i.e., SysML, optionally with feature models) in order to integrate social concepts early in SCPS requirements, design, simulation, optimization, and implementation activities. To help guarantee system quality and compliance during both design time and runtime adaptations, the thesis translates goal and feature models to mathematical functions used to validate possible design and adaptation alternatives during simulations at design time and adaptations at runtime. Feature model functions help constrain candidate goal model functions to valid solutions. These functions are used outside goal and feature modeling tools and are combined with SysML models, simulations, constraint solvers, and implementation tools. Furthermore, an integration between GRL and SysML models via a third-party requirements management system is achieved in order to strengthen system traceability and help ensure that stakeholder goals are considered properly during the SCPS development process. The main contributions of this thesis are: 1. An approach to integrate social concerns with CPSs, called CGS4Adaptation, composed of three independent methods supporting: (a) System design in SysML with a companion goal view, to support the documentation and consideration of goal-based rationales behind requirements and design elements, traceability and change management, impact analysis, and consistency and completeness checks (between the elements of goal and SysML models). (b) System optimization and simulation, to select and validate system designs, as well as adaptation strategies predefined at design time for common contexts and generated at runtime for unforeseen contexts. (c) System implementation, to support systems in choosing between adaptation alternatives at runtime while monitoring their quality and compliance. 2. A new and integrated arithmetic semantics for standard GRL, optionally combined with feature models.

3. An automated transformation of GRL models, and optionally feature models, to mathematical functions in multiple programming languages. Such code allows for quantitative GRL and FM model evaluations to be performed outside of modeling tools, including in running systems.