A novel scheduling scheme

called Two-Dimensional Priority Real-Time Scheduling (TDPRTS)

is proposed for open systems.This scheme not only sets task priority

but also sets scheduling policy priority.The execution order of task is determined by both task priority and its scheduling policy priority.It can not only separate scheduling mechanism from scheduling policy but also improves the performance.This scheme also introduces the CPU bandwidth control so as to realize different real time systems with different goals

such as hard

soft and hybrid real time systems.It also simplifies the schedulability analysis of the tasks

and it can provide the services with different QoS to the users with different rights and levels.This mechanism has high efficiency and high open degree.It can be used to extensive fields and has high extensibility.