Distributed Elevator Control System
|
- The physical configuration consists of multiple nodes interconnected by a local area network.
- Multiple instances of the Elevator Subsystem (one instance per elevator)
- Multiple instances of the Floor Subsystem (one instance per floor)
- One instance of the Scheduler subsystem
- All communication between the subsystems is via loosely coupled message communication.
- There is no shared memory in a distributed configuration; thus the gSchedulerh and multiple instances of the gElevator Subsystemhcan not directly access the gElevator Status & Planh data abstraction object.
- Client-Server solution presents the potential danger of crating a bottleneck at this server. Instead, an alternative solution is to use replicated data. Each instance of the Elevator Subsystem maintains its own local instance of the Elevator Status & Plan, called Local Elevator Status & Plan. The scheduler also maintains a copy of the Elevator Status & Plan, called Overall Elevator Status & Plan.