Cloud Integration Library

This project, developed in Java 21, implements a library that facilitates the development of integrations with cloud services, using custom annotations. It provides a simplified interface for communication with Google Pub/Sub and implements retry mechanisms for Feign calls, optimizing the reliability and robustness of applications.

Features

Pub/Sub

• @PubSubListener: Facilitates the creation of listeners for Google Pub/Sub topics, processing messages asynchronously and with support for custom error handling.
• PubSubListenerErrorHandler: Free interface to implement a handler that handles and redirects failed messages, allowing discarding, retrying or sending to secondary queues.

Feign Retry

• @FeignRetry: Adds automatic support for resending attempts in API calls using Feign, with flexible backoff configuration and maximum number of attempts.
• Exponential Backoff Support: Allows the configuration of retry strategies with exponential backoff, avoiding request overloads in external APIs.

Requirements

• Java 21: This project requires Java 21 to run.
• Spring Boot: This project was developed on top of v3.4.0 of Spring Boot.
• Spring Cloud: This project was developed on top of v2024.0.0 of Spring Cloud.
• Google Cloud: This project was developed on top of v26.51.0 of Google Cloud.
• Maven: Used as a build system to manage dependencies and plugins.

Installation

1. Clone the repository:

   git clone https://github.com/maurigre/cloud-common.git

2. Navigate to the project directory:

   cd cloud-common

3. Build the project:

   mvn clean install

Configuration

Maven

Add the following dependencies to your pom.xml:

<dependencies>
    <!-- Feign and Pub/Sub -->
    <dependency>
        <groupId>io.github.maurigre.cloud</groupId>
        <artifactId>common-bom</artifactId>
        <version>1.0.0</version>
    </dependency>

    <!-- Feign -->
    <dependency>
        <groupId>io.github.maurigre.cloud</groupId>
        <artifactId>feign-retry-annotation</artifactId>
        <version>1.0.0</version>
    </dependency>

    <!-- Pub/Sub -->
    <dependency>
        <groupId>io.github.maurigre.cloud</groupId>
        <artifactId>pubsub-annotation</artifactId>
        <version>1.0.0</version>
    </dependency>
</dependencies>

Make sure you are using Java 21 in your Maven build configuration:

<properties>
    <java.version>21</java.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.10.1</version>
            <configuration>
                <source>${java.version}</source>
                <target>${java.version}</source>
            </configuration>
        </plugin>
    </plugins>
</build>

Usage

Pub/Sub Listener

To create a listener for Pub/Sub, use the @PubSubListener annotation on the method that will process the messages. Example:

@PubSubListener(subscription = "my-subscription", errorHandler = "MyPubSubErrorHandler")
public void onMessage(PubsubMessage message) {
    // Processa a mensagem recebida
    log.info("Mensagem recebida: " + message.getData().toStringUtf8());
}

Feign Retry

1. Setting values directly in code

@FeignClient(name = "my-service")
public interface MyFeignClient {

    @FeignRetry(maxAttempts = 5, backoff = @Backoff(delay = 2000, multiplier = 2))
    @GetMapping("/api/resource")
    ResponseEntity<Resource> getResource();
}

2. Using variables configured in application.yml

@FeignClient(name = "my-service")
public interface MyFeignClient {

    @FeignRetry(maxAttempts = "${feign.retry.max-attempts}",
        backoff = @Backoff(
            delay = "${feign.retry.backoff.delay}",
            maxDelay = "${feign.retry.backoff.max-delay}",
            multiplier = "${feign.retry.backoff.multiplier}"))
    @GetMapping("/api/resource")
    ResponseEntity<Resource> getResource();
}

Suggested Retry configuration via application.yml

feign:
    retry:
        max-attempts: 5
    backoff:
        delay: 2000
        max-delay: 10000
        multiplier: 2

Error Handling in Pub/Sub

Implement the error handler to manage messages that failed to process:

@Component(value = "pubSubErrorHandler")
public class PubSubErrorHandler implements PubSubListenerErrorHandler {

    @Override
    public void handleError(PubsubMessage message, Throwable throwable) {
        // Lógica de tratamento de erro
        log.error("Erro ao processar mensagem: " + message.getMessageId(), throwable);
        // Enviar para fila de Dead Letter, descartar ou tentar novamente
    }
}

Contribution

Contributions are welcome! To contribute:

1. Fork the project.
2. Create a branch with your feature: git checkout -b my-feature.
3. Commit your changes: git commit -m 'My new feature'.
4. Push to the remote repository: git push origin my-feature.
5. Open a Pull Request.

License

This project is licensed under the MIT License.

Contact

For questions or suggestions, please contact maurigre@gmail.com.