The dependency management framework: a case study of the ION CubeSat

Due to the complexity and requirements of modern realtime systems, multiple teams must often work concurrently and independently to develop the various components of the system. Since a team typically only knows the dependency relations between the components they wrote and those they directly use, keeping track of system-wide dependency relations is not possible for any individual team. To further complicate matters, dependency relations often change as software components are refined or their interactions modified. Because the robustness of any real-time system hinges on the availability of essential services in spite of faults and failures in useful but non-essential components, keeping track of the constantly evolving dependency relations between the system´s components is crucial. If a system´s designers cannot ensure that critical services only USE but do not DEPEND ON less critical components, a seemingly minor fault can propagate along complex and unforeseen dependency chains and bring down the entire system. Therefore, automatically tracking and analyzing system-wide dependency relations given only local dependency information is vital for the development of robust real time systems. This paper presents DMF (dependency management framework), a prototype toolkit for dependency management in designing robust real-time systems. We demonstrate the usability and scalability of DMF with a case study of ION CubeSat, the University of Illinois at Urbana-Champaign ´s first student-developed satellite