Start by clarifying requirements and scale (e.g., number of users, orders per second, geographic scope), then outline high-level components like user service, restaurant service, order service, delivery service, and payment service. Dive into data modeling and API design for core flows (search, order placement, tracking), and discuss trade-offs in consistency, availability, and latency.
Pro tip: Emphasize real-time tracking and dispatch as the hardest parts: discuss how to match drivers to orders efficiently using geospatial indexing and a dispatch algorithm, and how to handle location updates at scale with WebSockets or long polling.
Ask questions to understand functional and non-functional requirements: user types (consumer, restaurant, driver), core features (search, order, pay, track), scale (DAU, orders/sec, peak), and constraints (latency, consistency, availability).
Sketch the main services (API gateway, user, restaurant, order, delivery, payment, notification) and data stores (SQL for transactions, NoSQL for scalability, cache, search index). Explain how they interact.
Define key entities (User, Restaurant, MenuItem, Order, Delivery, Payment) and their relationships. Design RESTful or GraphQL APIs for core flows: search restaurants, place order, update order status, track delivery.
Pick 1-2 challenging areas (e.g., real-time tracking, dispatch, payment consistency) and detail the design: geospatial indexing, WebSocket connections, idempotency, distributed transactions.
Discuss partitioning, replication, caching, load balancing, fault tolerance, and consistency vs. availability trade-offs. Mention monitoring, rate limiting, and security.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.