Node and Backend
Node and Backend Prerequisites Complete 094–108 and understand HTTP, middleware, authentication, testing, and safe errors. Topics - libuv, event-loop phases, streams, backpressure, buffers, and pipeline failure; - worker
Prerequisites
Complete 094–108 and understand HTTP, middleware, authentication, testing, and safe errors.
Topics
- libuv, event-loop phases, streams, backpressure, buffers, and pipeline failure;
- worker threads, child processes, filesystem boundaries, and crypto APIs;
- queues, scheduled jobs, idempotency keys, retry budgets, and dead letters;
- rate limiting, overload behavior, graceful shutdown, and connection pools;
- correlation IDs, structured logs, metrics, traces, OpenAPI, and contract tests.
Investigation
Add a background notification job to the task service. Define its durable state machine, idempotency key, retry and dead-letter policy, metrics, shutdown behavior, and tests for duplicate delivery.
Interview checkpoint
Explain why blocking CPU work harms unrelated requests, why retries can amplify an outage, and how a queue changes the client contract.