Circuit Breaker & Resilience with Resilience4j

    Question 1: CIRCUIT BREAKEER - Purpose of Circuit Breaker

    What is the main goal of using a Circuit Breaker in a microservice?

    Question 2: CIRCUIT BREAKEER - States of Circuit Breaker

    Which is not a valid state of Resilience4j Circuit Breaker?

    Question 3: CIRCUIT BREAKEER - Code Snippet (Annotation Usage)

    What does this method do?

    @CircuitBreaker(name = "orderService", fallbackMethod = "orderFallback")
public String placeOrder() {
    return restTemplate.getForObject("http://payment-service/pay", String.class);
}

    Question 4: RESILIENCE - Fallback Method Rule

    In Resilience4j, what must be true for a fallback method?

    Question 5: CIRCUIT BREAKEER - Code Snippet (Config in application.yml)

    What does the following config do?

    resilience4j.circuitbreaker:
  instances:
    orderService:
      failureRateThreshold: 50
      waitDurationInOpenState: 10s

    Question 6: RESILIENCE - Retry Mechanism

    In Resilience4j, what does the `@Retry` annotation do?

    Question 7: CIRCUIT BREAKEER - Code Snippet (Retry Example)

    What is the effect of this snippet?

    @Retry(name = "paymentRetry", fallbackMethod = "paymentFallback")
public String processPayment() {
    return paymentClient.pay();
}

    Question 8: RESILIENCE - Bulkhead Pattern

    What does the Bulkhead feature in Resilience4j achieve?

    Question 9: CIRCUIT BREAKEER - Time Limiter

    What does the TimeLimiter module in Resilience4j do?

    Question 10: RESILIENCE - Code Snippet (Chained Resilience Features)

    What does this configuration achieve?

    @CircuitBreaker(name = "inventoryService", fallbackMethod = "inventoryFallback")
@Retry(name = "inventoryRetry")
@TimeLimiter(name = "inventoryTimeout")
public CompletableFuture<String> checkInventory() {
    return CompletableFuture.supplyAsync(() -> inventoryClient.check());
}