Design a supermarket checkout system
Design a Supermarket Checkout System
Design the software for a supermarket checkout system. The system must support multiple checkout lanes operated by cashiers and be extensible to include self-checkout functionality in the future.
Customers bring items to a register, where a cashier scans products, and the system computes the final total.
The system should support the following core functionalities:
Product Management
- Product lookup by barcode or PLU code.
- Handling of both unit-based and weight-based items.
- Managing quantities for the same item.
Transaction Processing
- Application of taxes, discounts, promotions, and coupons.
- Maintaining a running subtotal as items are scanned.
- Ability to void an item before payment is finalized.
- Support for multiple payment methods, including cash and card.
- Generation of a detailed receipt upon transaction completion.
Operational Management
- Opening and closing a register session for a cashier.
Discussion Points
The design discussion should cover:
- The core objects/classes and their responsibilities.
- The main APIs or service boundaries.
- The checkout session lifecycle and its state transitions.
- How pricing and promotions should be modeled cleanly.
- Error handling and data consistency concerns.
- Strategies for extending the design to incorporate future features such as loyalty programs, returns processing, and split payments.
AI interview prep
Core dilemma
Balancing the complexity and real-time application of diverse business rules (pricing, promotions, taxes) with strict transactional consistency and extensibility for future features, all within a potentially distributed store environment.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Design a supermarket checkout system
Design a Supermarket Checkout System
Design the software for a supermarket checkout system. The system must support multiple checkout lanes operated by cashiers and be extensible to include self-checkout functionality in the future.
Customers bring items to a register, where a cashier scans products, and the system computes the final total.
The system should support the following core functionalities:
Product Management
- Product lookup by barcode or PLU code.
- Handling of both unit-based and weight-based items.
- Managing quantities for the same item.
Transaction Processing
- Application of taxes, discounts, promotions, and coupons.
- Maintaining a running subtotal as items are scanned.
- Ability to void an item before payment is finalized.
- Support for multiple payment methods, including cash and card.
- Generation of a detailed receipt upon transaction completion.
Operational Management
- Opening and closing a register session for a cashier.
Discussion Points
The design discussion should cover:
- The core objects/classes and their responsibilities.
- The main APIs or service boundaries.
- The checkout session lifecycle and its state transitions.
- How pricing and promotions should be modeled cleanly.
- Error handling and data consistency concerns.
- Strategies for extending the design to incorporate future features such as loyalty programs, returns processing, and split payments.