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Software Architecture Guide

Requirements-Decision Modeling for Cyber-Physical Systems of Systems

Explanation

Section titled “Explanation”

Cyber-physical systems (CPS) combine software with physical devices. A cyber-physical system of systems (CPSoS) joins several such systems. The research project TaSSAreCt studies how software architecture can support the sustainability, quality, and long-term evolution of these systems. The Swiss National Science Foundation funds it, and it runs from 2025 to 2028.

One project goal is to find out how CPS influence traditional non-functional properties and new ones. Non-functional requirements (NFRs) describe qualities a system must have, such as speed or reliability. See the articles Quality Attribute and Architectural Decision for background.

ReDeMo is a formal model that links NFRs with architectural decisions. A formal model states these links in a precise, structured way.

The project also builds a knowledge base of architectural decisions and requirements in CPS. The model is implemented in a toolchain based on SysML v2, a modeling language, to support architects.

Sustainability is a key NFR category in this work. It matters most for resource-constrained CPS, which have limited resources to work with.

The University of St. Gallen (HSG) leads the project. ZHAW is listed as a partner.

Example

Section titled “Example”

A team builds a network of battery-powered field sensors. One requirement says the sensors must run for years without a battery change. Another says they must report readings quickly. With a requirements-to-decisions model, the team records both requirements. It then links each decision, such as how often a sensor transmits, to the requirements it affects. Later, anyone who questions a decision can see which requirements it serves.

Trade-offs

Section titled “Trade-offs”

The available facts do not describe the model’s costs or limits. The project runs until 2028, so the model and toolchain are research work in progress. Treat them as an approach to watch, not a settled standard.

Requirements linked to decisions, supported by a knowledge base and a toolchain.

Diagram source 
flowchart LR
  R[Non-functional requirements] -->|linked by ReDeMo| D[Architectural decisions]
  K[Knowledge base] --> D
  T[SysML v2 toolchain] --> D

Checks

Section titled “Checks”
  • Non-functional requirements are explicitly linked to the architectural decisions that address them.
  • Sustainability is considered as a requirement category for resource-constrained cyber-physical systems.
  • Architectural decisions and requirements are collected in a shared knowledge base.
Section titled “Related”

Sources

Section titled “Sources”