Spring Cloud, Spring Boot ke UPAR TOOLS ka SET hai, MICROSERVICES architectures banaने ke liye. SERVICE DISCOVERY (Eureka) — HAR microservice STARTUP par khud REGISTER karti hai, aur DUSRI services usse NAAM SE dhoondती hain (hardcoded IP/port ke bajaye) — cloud environments mein, jaha IPs CONSTANTLY CHANGE hoti hain, ye ESSENTIAL hai.

API GATEWAY (Spring Cloud Gateway) EK SINGLE ENTRY POINT hai — CLIENT sirf Gateway se baat karta hai, jo request ko SAHI internal service tak ROUTE karta hai. Cross-cutting concerns (RATE LIMITING, AUTHENTICATION) YAHIN CENTRALIZE ho sakte hain, HAR individual service mein DUPLICATE karne ke bajaye.

// Eureka Server (registry):
@SpringBootApplication
@EnableEurekaServer
public class DiscoveryServerApplication { }

// Individual microservice — khud REGISTER karti hai:
@SpringBootApplication
@EnableDiscoveryClient
public class OrderServiceApplication { }

// Ek service, DUSRI ko NAAM se call karti hai (IP nahi):
@Service
public class OrderService {
    private final WebClient.Builder webClientBuilder;

    public Inventory checkInventory(Long productId) {
        return webClientBuilder.build()
            .get()
            .uri("http://inventory-service/api/inventory/" + productId)  // service NAME, IP nahi
            .retrieve()
            .bodyToMono(Inventory.class)
            .block();
    }
}