Evolution of complex mission-critical software systems based on development and runtime cooperation

Software is becoming part of the human societal infrastructure. This kind of software system is characterized by both “complexity” and “criticality”. Throughout their whole lifecycle, both user requirements and running environments undergo frequent changes. Traditional software engineering approaches struggle to provide effective support for such systems, making this a pressing challenge in current practice. To meet this challenge, it is necessary to introduce the “building, using, and upgrading simultaneously” approach, allowing the system's evolution to keep pace with its external changes. However, complex mission-critical software systems operate in highly regulated environments, characterized by reliable quality of service assurance, high integration of information, physical, and social aspects, numerous stakeholders, which results in their unique software evolution laws and makes it difficult to simply copy practices from other fields, such as Internet software. Based on the analysis of the characteristics of complex mission-critical software systems, we propose an evolution method for this kind of software system, TrustieEvo, which is closely integrated with development and runtime activities and driven by multiple stakeholders. Its core enabling mechanisms are presented in three aspects: continuous requirement management, trusted version iteration, and system resilience enhancement, and the corresponding software platform design is also presented. TrustieEvo has been successfully applied to the continuous evolution of a real complex mission-critical software system for nearly five years, reducing the requirement implementation cycle from “years” to “weeks” from the proposal of new user requirements to the formation of new software capabilities, and has withstood high-intensity validation in practice.