On Interfaces to Support Agile Architecting in Automotive: An Exploratory Case Study

Practitioners struggle with creating and evolving an architecture when developing complex and safety-critical systems in large-scale agile contexts. A key issue is the trade-off between upfront planning and flexibility to embrace change. In particular, the coordination of interfaces is an important challenge, as interfaces determine and regulate the exchange of information between components, subsystems, and systems, which are often developed by multiple teams. In a fast-changing environment, boundary objects between teams can provide the sufficient stability to align software or systems, while maintaining a sufficient degree of autonomy. However, a better understanding of interfaces as boundary objects is needed to give practical guidance. This paper presents an exploratory case study with an automotive OEM to identify characteristics of different interfaces, from non-critical interfaces that can be changed frequently and quickly, to those that are critical and require more stability and a rigorous change process. We identify what dimensions impact how interfaces are changed, what categories of interfaces exist along these dimensions, and how categories of interfaces change over time. We conclude with suggestions for practices to manage the different categories of interfaces in large-scale agile development.