2. Hard real time system
Strict timing constraints
High performance
Guaranteed response time constraints
So, the entire database sits in the main memory
3. 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
4.
5. 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
6. 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.