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Using Feign REST Client for Service Invocation

Feign is a Java-based declarative web service client developed by Netflix. It simplifies the process of making HTTP requests to RESTful web services by allowing you to define API requests as Java interfaces, and it handles the rest of the HTTP communication for you. Feign is often used in microservices architectures to communicate between services.

Here’s how you can use Feign as a REST client for service invocation:

1. Add Feign to Your Project: You need to include the Feign dependency in your project. If you’re using Maven, add the following dependency to your pom.xml file:


If you’re not using Spring Boot or Spring Cloud, you can still use Feign independently by including the appropriate Feign dependency.

2. Create a Feign Client Interface:

In Feign, you create an interface that defines the HTTP requests you want to make. Each method in the interface corresponds to an HTTP endpoint you want to call. You can use annotations like @RequestMapping, @GetMapping, @PostMapping, etc., to define the HTTP method and URL template. Here’s an example:

					import org.springframework.cloud.openfeign
import org.springframework.web.bind.annotation

@FeignClient(name = "example-service", url 
= "http://example.com")
public interface ExampleServiceClient {

    String getResource
    (@PathVariable("id") Long id);


In this example, @FeignClient specifies the target service and base URL, and the getResource method defines a GET request to retrieve a resource.

3. Use the Feign Client in Your Code:

You can inject the Feign client interface into your service or controller and use it to make API calls. Here’s an example:

public class MyService {

    private final ExampleServiceClient 

    public MyService(ExampleServiceClient 
    exampleServiceClient) {
        this.exampleServiceClient = 

    public String fetchResource
    (Long resourceId) {
        return exampleServiceClient


4. Configure Feign:

You might need to configure Feign to modify its behavior, such as setting request timeouts, error handling, or authentication. You can do this by creating a FeignClient configuration class or using properties in your application.yml or application.properties file.

For example, to set a connection timeout and read timeout for your Feign client, you can add properties to your application.yml:

        connectTimeout: 5000
        readTimeout: 5000


That’s the basic process of using Feign as a REST client for service invocation. Feign simplifies the communication between services by allowing you to work with Java interfaces and annotations rather than manually crafting HTTP requests.

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