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Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Baeldung)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Microsoft – NPI EA (cat= Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, you can get started over on the documentation page.

And, you can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat=Spring)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

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Partner – Orkes – NPI EA (tag=Microservices)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

eBook – Guide Spring Cloud – NPI EA (cat=Spring Cloud)
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eBook – Mockito – NPI EA (tag = Mockito)
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Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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eBook – Java Streams – NPI EA (cat=Java Streams)
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Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.

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To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:

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eBook – Jackson – NPI EA (cat=Jackson)
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Building a REST API with Spring?

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Course – LS – NPI EA (cat=Jackson)
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Get started with Spring and Spring Boot, through the Learn Spring course:

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Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:

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Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.

I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.

You can explore the course here:

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Course – All Access – NPI EA (cat= Spring)
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All Access is finally out, with all of my Spring courses. Learn JUnit is out as well, and Learn Maven is coming fast. And, of course, quite a bit more affordable. Finally.

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Course – LSD – NPI EA (tag=Spring Data JPA)
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Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.

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Partner – LambdaTest – NPI EA (cat=Testing)
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End-to-end testing is a very useful method to make sure that your application works as intended. This highlights issues in the overall functionality of the software, that the unit and integration test stages may miss.

Playwright is an easy-to-use, but powerful tool that automates end-to-end testing, and supports all modern browsers and platforms.

When coupled with LambdaTest (an AI-powered cloud-based test execution platform) it can be further scaled to run the Playwright scripts in parallel across 3000+ browser and device combinations:

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eBook – Guide Spring Cloud – NPI (cat=Cloud/Spring Cloud)
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1. Overview

So far, in our cloud application, we’ve used the Gateway Pattern to support two main features.

First, we insulated our clients from each service, eliminating the need for cross-origin support. Next, we implemented locating instances of services using Eureka.

In this article, we are going to look at how to use the Gateway pattern to retrieve data from multiple services with a single request. To do this, we’re going to introduce Feign into our gateway to help write the API calls to our services.

To read up on how to use the OpenFeign client check out this article.

Spring Cloud now also provides the Spring Cloud Gateway project which implements this pattern.

2. Setup

Let’s open up the pom.xml of our gateway server and add the dependency for OpenFeign:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

For reference – we can find the latest versions on Maven Central (spring-cloud-starter-feign).

Now that we have the support for building a OpenFeign client, let’s enable it in the GatewayApplication.java:

@EnableFeignClients
public class GatewayApplication { ... }

Now let’s set up OpenFeign clients for the book and rating services.

3. OpenFeign Clients

3.1. Book Client

Let’s create a new interface called BooksClient.java:

@FeignClient("book-service")
public interface BooksClient {
 
    @RequestMapping(value = "/books/{bookId}", method = RequestMethod.GET)
    Book getBookById(@PathVariable("bookId") Long bookId);
}

With this interface, we’re instructing Spring to create a OpenFeign client that will access the “/books/{bookId}” endpoint. When called, the getBookById method will make an HTTP call to the endpoint, and make use of the bookId parameter.

To make this work we need to add a Book.java DTO:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Book {
 
    private Long id;
    private String author;
    private String title;
    private List<Rating> ratings;
    
    // getters and setters
}

Let’s move on to the RatingsClient.

3.2. Ratings Client

Let’s create an interface called RatingsClient:

@FeignClient("rating-service")
public interface RatingsClient {
 
    @RequestMapping(value = "/ratings", method = RequestMethod.GET)
    List<Rating> getRatingsByBookId(
      @RequestParam("bookId") Long bookId, 
      @RequestHeader("Cookie") String session);
    
}

Like with the BookClient, the method exposed here will make a rest call to our rating service and return the list of ratings for a book.

However, this endpoint is secured. To be able to access this endpoint properly we need to pass the user’s session to the request.

We do this using the @RequestHeader annotation. This will instruct OpenFeign to write the value of that variable to the request’s header. In our case, we are writing to the Cookie header because Spring Session will be looking for our session in a cookie.

In our case, we are writing to the Cookie header because Spring Session will be looking for our session in a cookie.

Finally, let’s add a Rating.java DTO:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Rating {
    private Long id;
    private Long bookId;
    private int stars;
}

Now, both clients are complete. Let’s put them to use!

4. Combined Request

One common use case for the Gateway pattern is to have endpoints that encapsulate commonly called services. This can increase performance by reducing the number of client requests.

To do this let’s create a controller and call it CombinedController.java:

@RestController
@RequestMapping("/combined")
public class CombinedController { ... }

Next, let’s wire in our newly created OpenFeign clients:

private BooksClient booksClient;
private RatingsClient ratingsClient;

@Autowired
public CombinedController(
  BooksClient booksClient, 
  RatingsClient ratingsClient) {
 
    this.booksClient = booksClient;
    this.ratingsClient = ratingsClient;
}

And finally let’s create a GET request that combines these two endpoints and returns a single book with its ratings loaded:

@GetMapping
public Book getCombinedResponse(
  @RequestParam Long bookId,
  @CookieValue("SESSION") String session) {
 
    Book book = booksClient.getBookById(bookId);
    List<Rating> ratings = ratingsClient.getRatingsByBookId(bookId, "SESSION="+session);
    book.setRatings(ratings);
    return book;
}

Notice that we are setting the session value using the @CookieValue annotation that extracts it from the request.

There it is! We have a combined endpoint in our gateway that reduces network calls between the client and the system!

5. Testing

Let’s make sure our new endpoint is working.

Navigate to LiveTest.java and let’s add a test for our combined endpoint:

@Test
public void accessCombinedEndpoint() {
    Response response = RestAssured.given()
      .auth()
      .form("user", "password", formConfig)
      .get(ROOT_URI + "/combined?bookId=1");
 
    assertEquals(HttpStatus.OK.value(), response.getStatusCode());
    assertNotNull(response.getBody());
 
    Book result = response.as(Book.class);
 
    assertEquals(new Long(1), result.getId());
    assertNotNull(result.getRatings());
    assertTrue(result.getRatings().size() > 0);
}

Start up Redis, and then run each service in our application: config, discovery, zipkin, gateway, book, and the rating service.

Once everything is up, run the new test to confirm it is working.

6. Conclusion

We’ve seen how to integrate OpenFeign into our gateway to build a specialized endpoint. We can leverage this information to build any API we need to support. Most importantly we see that we are not trapped by a one-size-fits-all API that only exposes individual resources.

Using the Gateway pattern we can set up our gateway service to each client’s needs uniquely. This creates decoupling giving our services the freedom to evolve as they need, remaining lean and focused on one area of the application.

The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
Baeldung Pro – NPI EA (cat = Baeldung)
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Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:

>> Explore a clean Baeldung

Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat = Spring)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

Partner – Orkes – NPI EA (tag = Microservices)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

eBook – HTTP Client – NPI EA (cat=HTTP Client-Side)
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The Apache HTTP Client is a very robust library, suitable for both simple and advanced use cases when testing HTTP endpoints. Check out our guide covering basic request and response handling, as well as security, cookies, timeouts, and more:

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.

Get started with understanding multi-threaded applications with our Java Concurrency guide:

>> Download the eBook

eBook – Java Streams – NPI EA (cat=Java Streams)
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Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.

But these can also be overused and fall into some common pitfalls.

To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:

>> Join Pro and download the eBook

eBook – Persistence – NPI EA (cat=Persistence)
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Working on getting your persistence layer right with Spring?

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Course – LS – NPI EA (cat=REST)

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Get started with Spring Boot and with core Spring, through the Learn Spring course:

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Course – Spring Sale 2025 – NPI EA (cat= Baeldung)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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Course – Spring Sale 2025 – NPI (All)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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Partner – Microsoft – NPI (cat=Spring)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

eBook Jackson – NPI EA – 3 (cat = Jackson)
eBook – eBook Guide Spring Cloud – NPI (cat=Cloud/Spring Cloud)