Spring Boot 4 Enterprise Architecture Guide

Spring Boot 4 represents a major evolution in Java enterprise engineering. With native support for Virtual Threads (Project Loom), AOT compilation via GraalVM, and reactive stream optimizations, building high-throughput services is faster than ever.

1. Virtual Threads Configuration

Virtual Threads allow thousands of concurrent requests without thread-per-request OS overhead:

server:
  port: 8080
spring:
  threads:
    virtual:
      enabled: true

2. Declarative HTTP Interfaces

Define REST clients cleanly with explicit annotations:

@HttpExchange("/api/v1/users")
public interface UserClient {
    @GetExchange("/{id}")
    UserResponse getUserById(@PathVariable("id") String id);
}

3. Production Readiness Checklist