Elevator, Floor, Request classes in LLD - Architecture Diagram

System Overview - Elevator, Floor, Request classes

This system models a building elevator control system. It manages elevator movements between floors based on user requests. Key requirements include handling multiple floor requests, moving elevators efficiently, and responding to user inputs promptly.

Architecture Diagram

User
  |
  v
Floor Panel
  |
  v
Request Handler
  |
  v
Elevator Controller
  |
  v
Elevator
  |
  v
Floor Sensors

Components

User

actor

Person who requests elevator service from floors or inside elevator

Floor Panel

input_interface

Interface on each floor to send elevator requests

Request Handler

service

Receives and queues requests from floor panels and elevator buttons

Elevator Controller

service

Decides elevator movement based on queued requests

Elevator

service

Physical elevator that moves between floors

Floor Sensors

sensor

Detects elevator position at floors

Request Flow - 8 Hops

User → Floor Panel

Floor Panel → Request Handler

Request Handler → Elevator Controller

Elevator Controller → Elevator

Elevator → Floor Sensors

Floor Sensors → Elevator Controller

Elevator Controller → Request Handler

Elevator Controller → Elevator

Failure Scenario

Component Fails:Request Handler

Impact:New elevator requests are not queued, causing elevator to ignore user calls

Mitigation:Implement retry logic and fallback queue storage; alert maintenance team for manual intervention

Architecture Quiz - 3 Questions

Which component decides the elevator's next move based on requests?

A Request Handler

B Elevator Controller

C Floor Panel

D Floor Sensors

Design Principle

This design separates concerns by using distinct components for input handling, request management, decision making, and physical elevator control. It ensures scalability and maintainability by decoupling user interface, logic, and hardware interaction.