Architecture evaluation in continuous development

Context: In automotive, stage-gate processes have previously been the norm, with architecture created mainly during an early phase and then used to guide subsequent development phases. Current iterative and Agile development methods, where the implementation evolves continuously, changes the role of architecture. Objective: We investigate how architecture evaluation can provide useful feedback during development of continuously evolving systems. Method: Starting from the Architecture Tradeoff Analysis Method (ATAM), we performed architecture evaluation, both in a national research project led by an automotive Original Equipment Manufacturer (OEM), and at the OEM, in the context of continuous development. This allows us to include the experience of several architects from different organizations over several years. Using data produced during the evaluations we perform a post-hoc analysis to derive initial findings. We then validate and refine these findings through a series of focus groups with architects and industry experts. Findings: We propose principles of continuous evaluation and evolution of architecture, and based on these discuss a roadmap for future research. Conclusion: In iterative development settings, the needs are different from what typical architecture evaluation methods provide. Our principles show the importance of dedicated feedback-loops for continuous evolution of systems and their architecture