Start by clarifying requirements and constraints (e.g., expected throughput, latency, consistency, and provider authentication). Then walk through the high-level architecture, detailing the REST API contract, request lifecycle, and scaling strategy. Emphasize trade-offs and how you would handle failures and ensure reliability.
Pro tip: Demonstrate maturity by discussing idempotency and asynchronous processing for long-running validations, and how you would handle partial failures and retries without duplicating listings.
Ask questions to understand expected request volume, latency SLAs, consistency needs, and provider authentication mechanisms. Define what 'validation' entails and whether it's synchronous or asynchronous.
Define endpoints, HTTP methods, request/response payloads, and status codes. Include authentication, idempotency keys, and error handling. Consider versioning and rate limiting.
Describe the flow from receiving a request, validating it, forwarding to the internal validation domain, and returning the result. Include error handling, retries, and timeouts.
Discuss horizontal scaling, load balancing, caching, and asynchronous processing (e.g., message queues) to handle high throughput and ensure resilience.
Compare synchronous vs. asynchronous validation, consistency vs. availability, and monolith vs. microservices. Explain your choices based on requirements.
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