Engineering lessons for systems of systems learned from service-oriented systems

In today's rapidly changing environment it is no longer possible for isolated systems to provide all the capabilities that are necessary to fulfill a mission. Therefore, there is an increasing trend towards interconnected systems of systems that provide capabilities not available in a single system. However, existing software and system engineering practices do not scale well to SoS-engineering a system of systems (SoS) is still an open problem with significant challenges. Understanding these challenges and providing engineering solutions will require a two-pronged approach. First, a top-down approach that models an SoS at an abstract level is essential to understand key concerns that exist independent of the technologies used to implement the SoS. SoS research challenges about these concerns are well understood now. Second, a bottom-up approach that focuses on abstracting the concepts and lessons learned from specific examples of engineering systems of systems is needed. Currently, the most common approaches for engineering software-intensive systems of systems are service-oriented architecture (SOA), Grid Computing, and Cloud Computing - all of which are distributed computing paradigms. In the future, newer technologies may replace or complement these existing engineering approaches. This paper focuses on the bottom-up approach by exploring several areas where lessons learned from SOA implementations can be abstracted and applied to systems of systems, regardless of the implementation technology.