Try resilience4j

📦 Recommended Downloadable Project

• resilience4j-spring-boot-demo:

A curated Spring Boot demo showcasing CircuitBreaker, Retry, Bulkhead, TimeLimiter, and RateLimiter patterns in practice using Resilience4j   .

⸻

✅ How to Get and Run It

1. Clone the repository:

git clone https://github.com/resilience4j/resilience4j-spring-boot-demo.git

cd resilience4j-spring-boot-demo

2. Build & run:

• Using Gradle:

./gradlew bootRun

• Or import into your IDE and run the Application.java entry point directly  .

3. Hit sample endpoints to trigger resilience mechanisms:

• Circuit breaker

• Retry with fallback

• Bulkhead and time limiter isolation

• Rate limiting

4. Inspect configurations in application.yml or application.properties:

• Tune parameters like slidingWindowSize, failureRateThreshold, maxAttempts, timeoutDuration, etc.   .

⸻

🛠️ How to Adapt for Your Book Catalog API

You can integrate this resilience demo into your Book API by following these steps:

• Add dependencies:

<dependency>

  <groupId>io.github.resilience4j</groupId>

  <artifactId>resilience4j-spring-boot3</artifactId>

</dependency>

<dependency>

  <groupId>org.springframework.boot</groupId>

  <artifactId>spring-boot-starter-aop</artifactId>

</dependency>

<dependency>

  <groupId>org.springframework.boot</groupId>

  <artifactId>spring-boot-starter-actuator</artifactId>

</dependency>

• Annotate service methods with resilience annotations:

@CircuitBreaker(name = "bookService", fallbackMethod = "fallbackGetAllBooks")

@Retry(name = "bookService", fallbackMethod = "fallbackGetAllBooks")

public List<BookResponse> getAllBooks() { … }

public List<BookResponse> fallbackGetAllBooks(Throwable ex) {

  // return cached data or default list

  return Collections.emptyList();

}

Optionally add @Bulkhead, @TimeLimiter, @RateLimiter as needed    .

• Configure resilience settings in your application.yml:

resilience4j:

  circuitbreaker:

    instances:

      bookService:

        slidingWindowSize: 5

        failureRateThreshold: 50

        waitDurationInOpenState: 5s

  retry:

    instances:

      bookService:

        maxAttempts: 3

        waitDuration: 1s

  bulkhead:

    instances:

      bookService:

        maxConcurrentCalls: 10

  timelimiter:

    instances:

      bookService:

        timeoutDuration: 2s

  ratelimiter:

    instances:

      bookService:

        limitForPeriod: 20

        limitRefreshPeriod: 1s

⸻

🌟 Summary

• The resilience4j-spring-boot-demo repo is a ready-to-run, downloadable Spring Boot project integrating resilience patterns across various examples.

• You can easily adapt it to your existing Book Catalog API to add retry/fallback, circuit breaking, bulkheading, timeout protection, and rate limiting as needed.

• The demo includes Actuator metrics and optional monitoring integrations (e.g. Prometheus/Grafana) for real-time visibility  .

⸻

Next Steps Suggestions:

a. Integrate this demo’s resilience layer directly into your Book API (adding annotations + config)

b. Add unit and integration tests with JUnit and Mockito to simulate timeouts, failures, and ensure fallback methods work correctly