WebClient is part of the new WebFlux Framework, built on top of Project Reactor. Let's see an example to learn how to to use it. Spring Framework 5 introduces WebClient, a component in the new Web Reactive framework that helps build reactive and non-blocking web applications. Architecture oriented. We will use the GET method for: Single user GET /customers/{id} List of customer GET /customers Let's look at the HTTP GET call using the Spring WebClient. Add dependencies in pom.xml. As WebClient is a part of Spring WebFlux, you can add it to the pom.xml or build.gradle file of your project via the spring-webflux dependency. That's cool because you want to start handling these errors gracefully. The juice for extracting the bytes is shown below, and is defined separately as it is used in the . When we make a web request, the data is often returned as JSON. Use static factory methods create () or create (String) , or builder () to prepare an instance. The second is a function that maps the response to a Mono or an Exception. Execution of the second parameter is based on the output of the first. Netty logging is included in Baeldung's post but isn't nearly as granular as the Jetty HTTP client. * <p>Internally delegates to {@link DataBufferUtils#takeUntilByteCount}. From the resulting DataBuffer we can then extract the byte data and pass it along to the interested party via the Consumer that was passed in during construction. T - response body type Parameters: bodyClass - the expected response body type Returns: the ResponseEntity with the decoded body Since: 5.2; toEntity <T> reactor.core.publisher.Mono<ResponseEntity<T>> toEntity(ParameterizedTypeReference<T> bodyTypeReference) So without further ado, here's a walk-through of the best method (in my opinion) to do request and response logging (with the HTTP body) in Spring Webclient, with examples, comments and output. The first line shows you the status code with the message. This will be called automatically if you're consuming the body through the retrieve() method. ClientResponseWrapper. Non-blocking, reactive client to perform HTTP requests, exposing a fluent, reactive API over underlying HTTP client libraries such as Reactor Netty. URI Query Parameters. We wrap the encodeValue() method and delegate the encoding job to the original superclass body in Line 13. Change the fetchUser () method: The first thing to notice is that the whole method is now in a try/catch block. We can use the exhange() method in case we need more details from response. WebClient interface is the main entry point for initiating web requests on the client side. Cloud with AWS. As you can see, it matches exactly what you put in the code above. Provides access to the response status and headers, and also methods to consume the response body. Add WebClient into your project. Discover Spring 5's WebClient - a new reactive RestTemplate alternative. Since Spring 5 release, WebClient is the recommended approach. 5. Now that you have an instance of WebClient, it's easy to call the downstream service to get a JSON object. Now you need to update UserService. WebClient - GET Request . 1. In this tutorial, we are going to show how to customize Spring's WebClient - a reactive HTTP client - to log requests and responses. Overview. In today's world, when we exchange data with other services, we use JSON as a preferred format. Specialised in backend technologies based in the Java ecosystem. contentLength (long contentLength) Set the length of the body in bytes, as specified by the Content-Length header. The retrieve() method returns a WebClient.ResponseSpec whose bodyToMono() extracts the response body to a Mono. It has a functional, fluent API with reactive types for . java; spring-boot . This question is similar to Spring Webflux : Webclient : Get body on error, which has no accepted answer and some of the suggested approaches use methods that are no deprecated. Interface WebClient. There are a few different ways to unwrap an asynchronous value. The onStatus method requires two parameters. Shortcut for body (BodyInserter) with a value inserter. It will close the resources properly under the . Updated status after a team call: the current WebClient API needs to be improved because of resource management issues: we should have a way to signal that we're done with the response so that resources can be closed/recycled; the draft changes in reactor netty address that issue internally but can be problematic for Framework since it limits our ability to use it as a . /**Consume up to the specified number of bytes from the response body and * cancel if any more data arrives. Reading the Body. We then need to unwrap that somehow, to trigger the request and get the response body content itself, once it's available. . To read the response body, we need to get a Mono (i.e: an async future value) for the contents of the response. Line 38 -Line 43 implements the searchMovieById() method in the same way, but by . 3. My suspicion is that this is not executed due to the blocking nature, as the response body is dealt with the bodyToMono after the onStatus. Spring 5 - WebClient Example. Spring Framework 5 has introduces WebClient (spring-webflux module), a part of the new Web Reactive framework that helps construct reactive and non-blocking web applications, is part of the Spring MVC project and allows communication with HTTP servers while adhering to RESTful standards. Follow along for the step by step instructions on how to use WebClient to do GET, POST, PUT and DELETE requests. Finally, we need to remember to keep the right order of actual segment values passed to the build () method. Usually, a query parameter is a simple key-value pair like title=Baeldung. It has a fluent, reactive API, and it uses HTTP protocol in its underlying implementation. In simple words, the Spring WebClient is a component that is used to make HTTP calls to other services. Prior to Spring 5, RestTemplate has been the main technique for client-side HTTP accesses, which is part of the Spring MVC project. The next several lines show you the headers sent back with the response. It was created as part of the Spring Web Reactive module and will be replacing the classic RestTemplate in these scenarios.In addition, the new client is a reactive, non-blocking solution that works over the HTTP/1.1 protocol. public interface WebClient. The class is very simple. Here's the method that handles retrieving a single user: public SalesOwner fetchUser(HttpServletRequest request) { final String requestTokenHeader = request.getHeader("Authorization"); SalesOwner salesOwner . GETting to the Bottom. The first is a predicate that takes in a status code. We use the GET method whenever we like to get/fetch the resources. For examples with a response body see: Represents an HTTP response, as returned by WebClient and also ExchangeFunction. 2. WebClient.RequestBodySpec. 1. What is WebClient? But does this mean we should be able to call that method at any time, even while reading the response body? Logging Spring WebClient Calls. Francisco Dorado. * @param maxByteCount the limit as number of bytes * @return the filter to limit the response size with * @since 5.1 */ public static ExchangeFilterFunction limitResponseSize(long . Spring released WebClient as part of Spring WebFlux framework. contentType ( MediaType contentType) Set the media type of the body, as specified by the Content-Type header. In the Spring Boot project, you can add spring-boot-starter-webflux instead. WebClient is a reactive and non-blocking interface for HTTP requests, based on Spring WebFlux. ClientHttpResponse#ignoreBody(); this method is an alternative to the response.bodyTo* ones. Currently working on Microservices using Spring Framework and AWS Cloud technologies. Java & Spring Backend (+10 years experience). public interface ClientResponse. Let's start by bootstrapping our application using Spring Initializer by selecting spring-boot-starter-webflux dependency. Simply put, WebClient is an interface representing the main entry point for performing web requests. From Spring 5, we get to use WebClient to perform these requests in a reactive, non-blocking way. The last line shows you the body of the response. Francisco Dorado Follow Software Architect at sngular.com in Seville. By the way, your Spring Boot application probably crashed. A URI can have as many path segments as required, though the final URI length must not exceed limitations. The Spring WebClient exchange method provides more control than the retrieve method but makes you responsible for consuming the body in every scenario. Spring WebClient is a non-blocking and reactive web client to perform HTTP requests.WebClient has been added in Spring 5 (spring-webflux module) and provides fluent functional style API.. WebClient. Spring 5 WebClient is reactive and non-blocking client for making HTTP requests. To make HTTP requests, you might have used Spring Rest Template, which was simple and always blocking web client. This tutorial guides us to use WebClient to access another service and consume its data in JSON form. Brian Clozel commented. It is part of Spring's web reactive framework, helps building reactive and non-blocking applications. The spring-webflux module includes a non-blocking, reactive client for HTTP requests with Reactive Streams back pressure. That's the object WebClient uses to store info about the response, such as the body, the headers, and the status code. The library versions can be omitted as it is resolved by the parent pom provided by Spring Boot WebClient.RequestBodySpec. . response -> Mono.error(new ServiceException("Method not allowed. In this case, if we see an INTERNAL_SERVER_ERROR (i.e., 500), we'll take the body, using bodyToMono . Spring recommends to use WebClient instead. Note, however, that the method catches WebClientResponseException and not ServiceException. Please check the URL.", response.statusCode().value())) The Function accepts as its input a ClientResponse object. For most of your use cases .retrieve() should be your go-to solution and if you need access to headers and the status code, you can still convert the response to a ResponseEntity .