How do you perform asynchronous HTTP requests in Spring Boot?

Table of Contents

• Introduction
• Methods to Perform Asynchronous HTTP Requests
  • 1. Using WebClient in Spring WebFlux
    • Example:
    • Explanation:
  • 2. Using CompletableFuture with RestTemplate
    • Example:
    • Explanation:
• Practical Examples
  • Example 1: Combining Multiple Asynchronous Calls
  • Example 2: Using CompletableFuture for Aggregating Results
• Conclusion

Introduction

Asynchronous HTTP requests in Spring Boot are crucial for building non-blocking, high-performance applications. These requests free up resources while waiting for responses, enabling the application to handle more concurrent tasks. Spring Boot supports asynchronous HTTP communication through WebClient in Spring WebFlux and CompletableFuture for managing async operations in a non-reactive context.

Methods to Perform Asynchronous HTTP Requests

1. Using WebClient in Spring WebFlux

WebClient is the recommended way to perform non-blocking HTTP requests in Spring Boot. It integrates seamlessly with the reactive programming model.

Example:

Explanation:

• **Mono**: Represents a single asynchronous value or failure.
• **subscribe**: Initiates the request and processes the response asynchronously.

2. Using CompletableFuture with RestTemplate

For non-reactive applications, CompletableFuture provides a way to execute HTTP requests asynchronously.

Example:

Explanation:

• **CompletableFuture.supplyAsync**: Runs the request on a separate thread.
• Suitable for applications not using reactive programming.

Practical Examples

Example 1: Combining Multiple Asynchronous Calls

Using WebClient to combine results from multiple asynchronous requests.

Example 2: Using CompletableFuture for Aggregating Results

Conclusion

Asynchronous HTTP requests in Spring Boot enhance application responsiveness and scalability. The WebClient is ideal for reactive environments, offering seamless integration with Project Reactor, while CompletableFuture works well in non-reactive contexts. Leveraging these tools ensures efficient HTTP communication, enabling modern, high-performance applications.