REAL TIME DATABASE

Hard real time database

Hard real time system Strict timing constraints High performance Guaranteed response time constraints So, the entire database sits in the main

memory

MDARTS

Multiprocessor Database Architecture for Real Time 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

and semantic constraints within the application code Constraint specification like Access time

Write < 80 micro sec Read < 50 micro sec Persistance -> volatile

MDARTS

MDARTS

Suitable for NGC (Next generation machine controllers) for automated factories

Transaction timing in the order of tens of microseconds

Control task Periodic task Extracts current sensor values from the

database and computes new control signal for the actuators

MDARTS

Data accessed extremely high speed must be stored in the physical shared memory as the virtual memory and disk based databases may generate the page faults

Applications need not know whether the database access is local or remote. The database handler hides the information of being remote. Remote access achieved through Remote Procedure calls (RPC).

There may be some communication delay when the data is accessed remotely. The shared data manager (SDM) tracks the location and identity of the shared memory objects and also constructs its own database handle for each object to service remote requests.