| Most existing real-time applications are implemented on stand-alone, embedded systems or on dedicated computers. Their schedulability is determined by analyzing all the applications together. With tremendous advances in hardware technologies, it is now possible to run realtime applications on fast, general purpose workstations and personal computers concurrently with non-real-time applications. A challenging problem is how to schedule an open system of complex, independently developed real-time applications and non-real-time applications.; This thesis proposes an architecture of the open system in which multiple independently developed real-time applications and non-real-time applications run concurrently. The open system uses a two-level hierarchical scheme to schedule the applications. The scheme allows the developer of each real-time application to validate the schedulability of the application independently of other applications. The open system always admits non-real-time applications, but it admits a real-time application only if the application passes the acceptance test provided by the system. Once a real-time application is created and admitted by the open system, its schedulability is guaranteed regardless of the behaviors of other applications that execute concurrently in the system.; This thesis also presents the design and the implementation of the open system as an extension to a general purpose thread-based operating system. The extension includes three components: (1) a two-level kernel scheduler and an admission control mechanism, (2) a set of system service providers, and (3) a set of real-time application programming interface (RTAPI) functions. |
