Requirements

Determine the different ways the system will be used. This includes main functions the system needs to perform and who will use it.


  • vehicle
    • size: compact, standard, oversized
    • type: might have others: regular, EVs, handicap accessible...
  • Ticket
    • record entry time, exit time
    • maybe spot
  • Gateway
    • use LPR service to get Vehicle size
    • assign ticket & spot & feedback
      • assigning strategy
        • best fit
        • FCFS
        • Nearest
        • ...
    • charging on leaving
      • Pricing strategy
        • spot type
        • vehicle type
        • duration
        • location
  • Spot
    • size: compact, standard, oversized
    • type: might have others: regular, EVs, handicap accessible...
    • spot are down-size compatible
    • location


Define Core Objects

Based on the requirements and use cases, identify the main objects of the system...


  • Parking Lot System
    • have multiple Gateway
    • have multiple Parking Spot
  • Gateway
    • can assign any spot to vehicles as long as they match
  • Parking Spot
  • Vehicle
  • Parking Tickets
    • each vehicle each entry correspond to 1 ticket



Analyze Relationships

Determine how these objects will interact with each other to fulfill the use cases...


Vehicle

  • send enter request
  • send leave request
  • pay ticket


Gateway

  • get vehicle meta data
  • assign spot & create ticket
  • charge


Parking Spot

  • scan ticket and car to unlock
  • lock after vehicle leaving






Establish Hierarchy

Design inheritance trees where applicable to promote code reuse and polymorphism. This step involves identifying common attributes and behaviors that can be abstracted into parent classes...






Design Patterns

Consider using design patterns (e.g., Factory, Singleton, Observer, Strategy) that fit the problem...






Define Class Members (write code)

Attributes: For each class, define the attributes (data) it will hold...

Methods: Define the methods (functions) that operate on the attributes. Ensure they align with the object's responsibilities and adhere to the principle of encapsulation.


public class Car { ... } // Example







Adhere to SOLID Guidelines

Check and explain whether your design adheres to solid principles (Ask interviewer what SOLID principle is if you can not recall it.)...






Consider Scalability and Flexibility

Explain how your design can handle changes in scale and whether it would be easily to extend with new functionalities...






Create/Explain your diagram(s)

Try creating a class, flow, state and/or sequence diagram using the diagramming tool. Mermaid flow diagrams can be used to represent system use cases. You can ask the interviewer bot to create a starter diagram if unfamiliar with the tool. Briefly explain your diagrams if necessary...






Future improvements

Critically examine your design for any flaws or areas for future improvement...