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Module Quiz

Complete this quiz after finishing all concept and practice pages. Save your answers before opening separate quiz calibration.

Current Module Questions​

Question 1: What Is an Event?​

State, in one sentence, the three non-negotiable properties of an event, and give one example of a "message" that is not an event and why.

Question 2: Event vs Command vs Query​

A team proposes a topic called order-events carrying PlaceOrder, OrderPlaced, GetOrderStatus, and CancelOrder. Identify each message's real intent and propose the corrected topic/endpoint for each.

Question 3: Pick the Messaging Pattern (Scenario 1)​

A checkout service publishes that an order was placed; four other services react (billing, inventory, notifications, analytics). Which messaging pattern and why?

Question 4: Pick the Messaging Pattern (Scenario 2)​

An image-processing service accepts upload events and generates thumbnails. 10 workers share the load. Which messaging pattern and why?

Question 5: The Outbox Pattern​

A service writes to Postgres and then publishes to Kafka. Sometimes, after a crash, the DB has the row but the broker does not have the event. Name the bug and describe the fix.

Question 6: Queue vs Log-Based Broker​

A team argues about RabbitMQ vs Kafka for "an event bus." What two questions decide the choice?

Question 7: Partitions and Consumer Groups​

A Kafka topic has 12 partitions. A consumer group has 20 consumers. What happens?

Question 8: Ordering Guarantees​

A saga orchestrator occasionally sees PaymentCaptured before OrderPlaced. List the two most likely causes.

Question 9: Choreography vs Orchestration​

A 20-step business workflow with timers, compensations, and several human approvals needs to be modeled across 12 services. Which topology and why?

Question 10: Saga Compensation​

In a checkout saga ReserveStock -> ChargeCard -> CreateShipment, CreateShipment fails. Walk the compensation.

Question 11: Idempotency and Exactly-Once​

Explain why "at-least-once delivery + idempotent consumers" is effectively exactly-once, and why stronger broker-level "exactly once" is not enough.

Question 12: Event Sourcing Fit​

Name three situations where event sourcing is overkill, and one where it is the natural fit.

Question 13: Projections and Rebuildability​

Why is it important that every projection be rebuildable, and what does that require of the event stream?

Question 14: CQRS Decision​

A 5-engineer startup with 2 simple CRUD screens and ~100 customers asks if they should use CQRS. Defend a recommendation.

Question 15: Integration Question -- Tie the Module Together​

A payments service emits PaymentCaptured. Downstream: a ledger service, a notification service, and an analytics pipeline. Describe the minimum production-quality integration end-to-end.

Interleaved Review Questions​

(5 questions from previous modules to maintain retention)

Prior Module Question 1 (from S8M2)​

What is a "distributed monolith," and what is the single most reliable signal that a microservices system has become one?

Prior Module Question 2 (from S8M1)​

In system design, what is the correct first step when a requirement is ambiguous -- and why not "start drawing components"?

Prior Module Question 3 (from S7)​

State the dependency rule in Clean Architecture in one sentence.

Prior Module Question 4 (from S6)​

What does "eventual consistency" actually promise, and what does it explicitly not promise?

Prior Module Question 5 (from S5)​

Why does a queue between a fast producer and a slow consumer not "solve" the throughput mismatch -- and what does it actually buy you?

Self-Assessment and Remediation​

Scoring and Advancement Criteria​

Mastery Level (90-100% correct):

  • Retrieval is strong; complete all module and semester evidence gates before advancing.
  • Action: Check the required assessment evidence before proceeding.

Proficient Level (75-89% correct):

  • Action: Review concept pages corresponding to missed questions; redo the matching kata.

Developing Level (60-74% correct):

  • Action: Rework Clusters 2 (messaging + outbox) and 4 (saga + idempotency). These are where most missed questions will cluster. Redo Practice 2 and 3 fully.

Insufficient Level (<60% correct):

  • Action: Return to Concepts 1-3 and rebuild the mental model before attempting the operational clusters. Without the "event is a past fact" discipline, the rest of this module does not stick.

Remediation Resources by Score Range​

75-89% Score Range:

  • Targeted Review: Re-read only the specific concept(s) behind missed questions.
  • Quick Practice: 2-3 additional scenarios from Practice 2 or 4.

60-74% Score Range:

  • Systematic Review: Full re-read of Clusters 2 and 4.
  • Extended Practice: All of Practice 3 (saga + idempotency) with different domains.
  • Alternative Explanations: Fowler's "What do you mean by Event-Driven?" and Richardson's saga article on microservices.io.

<60% Score Range:

  • Foundation Check: Verify S7M2 (event-driven topologies) is understood.
  • Comprehensive Remediation: Rework every concept page with notes in your own words.
  • Peer/Instructor: Explain "event vs command" and "the outbox pattern" out loud; the gap will surface quickly.

Progression boundary​

Quiz performance calibrates retrieval and reasoning. It does not replace runnable work, changed-case transfer, the module assessment or required semester evidence. Consult practice calibration for the additional independent cases.