Hard real time system Strict timing constraints High performance Guaranteed response time constraints So, the entire database sits in the main memory
Multiprocessor Database Architecture for RealTime System This is for hard real time systems Main memory database Object oriented (C++ elements) Support direct, concurrent, shared memory data access Support explicit declaration of real time constraints andsemantic constraints within the application code Constraint specification like Access time Write < 80 micro sec Read < 50 micro sec Persistance -> volatile
Suitable for NGC (Next generation machinecontrollers) for automated factories Transaction timing in the order of tens ofmicroseconds Control task Periodic task Extracts current sensor values from the database andcomputes new control signal for the actuators
Data accessed extremely high speed must be stored in thephysical shared memory as the virtual memory and diskbased databases may generate the page faults Applications need not know whether the database accessis local or remote. The database handler hides theinformation of being remote. Remote access achievedthrough Remote Procedure calls (RPC). There may be some communication delay when the datais accessed remotely. The shared data manager (SDM)tracks the location and identity of the shared memoryobjects and also constructs its own database handle foreach object to service remote requests.