Jumped straight into defining a Publisher and Subscriber interface, which felt right, but I fumbled when they pushed on how you'd handle multiple topics and fan-out.
Start by clarifying requirements and scope, then design the core object model with key abstractions like Publisher, Subscriber, Topic, and Broker. Discuss trade-offs in delivery semantics, scalability, and reliability, and iterate based on feedback.
Pro tip: Demonstrate Amazon leadership principles by proactively discussing operational excellence, such as monitoring, metrics, and failure handling, and tie design decisions to customer impact.
Ask questions to understand functional and non-functional requirements, such as message ordering, delivery guarantees, scalability, and latency.
Identify key objects and interfaces: Publisher, Subscriber, Topic, Broker, Message, and Subscription. Define their responsibilities and relationships.
Specify how components interact using design patterns (e.g., Observer, Mediator) and handle message flow, including publish, subscribe, and notify operations.
Discuss trade-offs in delivery semantics (at-least-once vs. exactly-once), ordering, partitioning, and how to scale the broker horizontally.
Cover fault tolerance, message persistence, monitoring, and how to handle failures and backpressure.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.