I started with a straightforward sequential loop and null-on-failure logic, which felt right but maybe too simple for the level they expected.
Start by clarifying requirements and constraints, then propose a high-level design that separates orchestration from downstream calls. Emphasize resilience patterns like timeouts, retries, and circuit breakers, and explain how to handle partial failures by returning a composite response with error details. Finally, discuss trade-offs and monitoring.
Pro tip: Demonstrate maturity by discussing how to handle partial failures gracefully—returning a 207 Multi-Status or a response with per-service status—and how to avoid cascading failures with bulkheads and fallbacks.
Ask about latency SLAs, expected failure rates, and whether the composite response should be all-or-nothing or allow partial success. Confirm if downstream services are idempotent and if retries are safe.
Outline a bootstrap API that sequentially calls three services, with each call wrapped in a resilient client (timeouts, retries, circuit breaker). Use a saga or orchestration pattern to manage the sequence and compensate on failure.
For call failures, catch exceptions and decide whether to retry, fallback, or mark that service as failed. For parse failures, validate responses and log errors, returning partial data with error indicators.
Aggregate successful outputs into a unified response, including metadata about which services succeeded or failed. Consider using a standard format like JSON with a 'status' field per service.
Compare sequential vs. parallel calls (if dependencies allow), synchronous vs. asynchronous processing, and consistency vs. availability. Highlight the need for logging, metrics, and tracing to monitor failures.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
This came as a natural follow-up and I was mostly okay on timeouts and retries.
Start by clarifying the current pattern and the requirements for timeouts, retries, and parallelism. Then, propose a layered design that adds these concerns without breaking existing functionality, discussing trade-offs and implementation details. Conclude with how you would test and monitor the enhanced pattern.
Pro tip: Emphasize idempotency and backoff strategies to avoid cascading failures, and mention how you'd use circuit breakers to prevent retry storms. Also, highlight the importance of context propagation for timeouts and cancellation.
Ask questions to understand the existing pattern (e.g., synchronous calls, error handling) and the specific needs for timeouts, retries, and parallelism. Clarify constraints like latency budgets, failure modes, and whether calls are idempotent.
Propose adding timeouts at multiple levels (e.g., per call, overall operation) using context propagation. Discuss how to handle cancellation and cleanup to avoid resource leaks.
Describe a retry mechanism with exponential backoff and jitter to avoid thundering herds. Mention idempotency keys and circuit breakers to prevent retrying non-idempotent operations or overwhelming downstream services.
Explain how to execute independent calls concurrently using futures, promises, or async/await, and how to aggregate results. Discuss handling partial failures and timeouts in parallel scenarios.
Discuss trade-offs like increased complexity, resource usage, and potential for retry storms. Outline testing strategies (e.g., chaos engineering) and monitoring (e.g., metrics for retries, timeouts, and latency).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.