How do microservices interact with each other?

Microservices interact with each other primarily through network protocols, using lightweight message exchange mechanisms. Main methods of interaction:

• HTTP/REST API — the most common way, where microservices exchange data via HTTP requests using JSON or XML.
• gRPC — a high-performance protocol based on HTTP/2 with support for binary serialization, suitable for internal communication.
• Messages through brokers (RabbitMQ, Kafka) — asynchronous message exchange, enabling event-driven architecture.

Important aspects:

• Each microservice has its own API and is responsible for its own domain.
• Interaction should be as loosely coupled as possible to ensure independent deployment and scaling.

Example of a simple REST call in Java using Spring Boot:

@RestController
public class UserController {
    @GetMapping("/users/{id}")
    public User getUser(@PathVariable String id) {
        // logic to get user
    }
}

// In another microservice
RestTemplate restTemplate = new RestTemplate();
User user = restTemplate.getForObject("http://user-service/users/123", User.class);