Analyzing Software Evolvability of an Industrial Automation Control System: A Case Study

Evolution of software systems is characterized by inevitable changes of software and increasing software complexity, which in turn may lead to huge maintenance and development costs. For long-lived systems, there is a need to address evolvability (i.e. a systempsilas ability to easily accommodate changes) explicitly in the requirements and early design phases, and maintain it during the entire lifecycle. This paper describes our work in analyzing and improving the evolvability of an industrial automation control system, and presents (1) evolvability subcharacteristics based on the problems in the case and available literature; (2) a structured method for analyzing evolvability at the architectural level - the ARchitecture Evolvability Analysis (AREA) method. This paper includes also the main analysis results and our observations during the evolvability analysis process in the case study. The evolvability subcharacteristics and the method should be generally applicable, and they are being validated within another domain at the time of writing.