For over a decade, the US Navy has been modernizing many of its large-scale, mission-/safety-critical, and software-intensive national security systems using an open systems architecture (OSA)¹ approach, which leverages capable and reliable standards-based commercial off-the-shelf (COTS) software infrastructure components and modern software development practices for iterative and incremental development. As with other mission-/safety-critical domains, such as air traffic management, power grid, and automotive systems, a key goal of the Navy's OSA strategy has been to field and manage affordable and superior capabilities more rapidly at reduced cost.