Explain how to make robust HTTP API calls

SWE Fundamentals: Making Robust HTTP Calls (Client/Service)

You need to integrate with an external HTTP API (could be an internal microservice or a third-party service). The call is on the critical path of a user request.

Prompt

Explain how you would implement this HTTP integration robustly:

• Which HTTP method(s) you would use and why
• Timeouts (connect/read), retries, and backoff
• Which failures are retryable vs not
• Authentication and headers
• Rate limiting and pagination
• Observability (logging/metrics/tracing)
• How you would avoid duplicate side effects (idempotency)

Assume high QPS and that the external API can be slow or intermittently failing.