Microservices Microservices 3 — Questions and Answers
Question 1: The Saga pattern is used primarily to manage:
- Distributed transactions across multiple services without a global lock (Correct answer)
- UI rendering
- Local file storage
- Single-database ACID commits
Correct answer: Distributed transactions across multiple services without a global lock
Sagas coordinate distributed transactions via a sequence of local transactions and compensations.
Question 2: In a choreography-based saga, services coordinate by:
- Publishing and reacting to events without a central orchestrator (Correct answer)
- A single controller commanding each step
- Sharing one database lock
- Calling a monolith
Correct answer: Publishing and reacting to events without a central orchestrator
Choreography relies on services emitting and reacting to events, with no central coordinator.
Question 3: What is a compensating transaction in a saga?
- An action that undoes the effect of a previously completed step on failure (Correct answer)
- A retry of the same step forever
- A database backup
- A new microservice
Correct answer: An action that undoes the effect of a previously completed step on failure
Compensating transactions semantically reverse prior steps when a later step fails.
Question 4: The Strangler Fig pattern is used to:
- Incrementally migrate a monolith to microservices by gradually replacing functionality (Correct answer)
- Delete all code at once
- Merge services into one binary
- Encrypt the monolith
Correct answer: Incrementally migrate a monolith to microservices by gradually replacing functionality
The Strangler Fig pattern gradually routes functionality away from a monolith to new services.
Question 5: What problem does the CQRS pattern address?
- Separating read and write models for scalability and clarity (Correct answer)
- Combining all services into one
- Removing all databases
- Disabling logging
Correct answer: Separating read and write models for scalability and clarity
CQRS separates command (write) and query (read) responsibilities into different models.
Question 6: Event sourcing stores application state as:
- A sequence of immutable events that can be replayed (Correct answer)
- Only the latest snapshot row
- Temporary in-memory values
- Compiled binaries
Correct answer: A sequence of immutable events that can be replayed
Event sourcing persists every state change as an append-only log of events.
Question 7: Which challenge is introduced by eventual consistency in microservices?
- Data may be temporarily out of sync across services until updates propagate (Correct answer)
- All data is always instantly consistent
- Databases stop working
- Services cannot communicate at all
Correct answer: Data may be temporarily out of sync across services until updates propagate
Eventual consistency means replicas converge over time, so brief inconsistencies can occur.
Microservices Microservices 3
The Saga pattern is used primarily to manage: