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LetsGit.IT/Categories/Monoliths
Monolithshard

Domain events inside a monolith: why use them and what are the pitfalls?

Tags
#monoliths#ddd#events#decoupling
Back to categoryPractice quiz

Answer

They decouple modules: one module publishes an event (“OrderPlaced”) and others react without tight coupling. Pitfalls: deciding sync vs async handling, avoiding doing heavy work inside the same transaction, and ensuring handlers are reliable and idempotent (events can be retried or processed twice).

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): monoliths, ddd, events, decoupling
  • Scaling: what scales horizontally vs vertically, where bottlenecks appear.
  • Reliability: retries/circuit breakers/idempotency, observability (logs/metrics/traces).
  • Evolution: keep changes cheap (boundaries, contracts, tests).
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "domain-events-inside-a-monolith:-why-use-them-an"
function explain() {
  // Start from the core idea:
  // They decouple modules: one module publishes an event (“OrderPlaced”) and others react with
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?

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