FSF provides for the temporal encapsulation of subsystems to support the composability and reusability of available components including legacy subsystems. FSF also represents a higher level of abstraction relative to the operating system primitives. It provides an abstract API that makes time a first class citizen, making it easier to build real-time applications. Instead of concentrating on condition variables, timers, or other low-level RTOS mechanisms, the application developer is able to think in terms of deadlines, execution time budgets, or high-level synchronization primitives.