1. Write a Java code snippet to create a simple microservice using Spring Boot.
@RestController
public class GreetingController {
@GetMapping("/greet")
public String greet() {
return "Hello from the microservice!";
}
}
2. Explain how you would implement inter-service communication in a microservices architecture.
Implementing inter-service communication can be done using technologies like RESTful APIs, gRPC, or message queues (e.g., RabbitMQ, Kafka). Here’s a code snippet for a simple RESTful communication in Java using Spring Cloud Feign:
Implementing inter-service communication can be done using technologies like RESTful APIs, gRPC, or message queues (e.g., RabbitMQ, Kafka). Here’s a code snippet for a simple RESTful communication in Java using Spring Cloud Feign:
@FeignClient(name = "other-service")
public interface OtherServiceClient {
@GetMapping("/other-service/endpoint")
String getFromOtherService();
}
3. Write code to demonstrate the use of a circuit breaker pattern (e.g., Hystrix) in microservices for handling failures.
@RestController
public class CircuitBreakerController {
@GetMapping("/fallback")
@HystrixCommand(fallbackMethod =
"fallbackMethod")
public String serviceWithCircuitBreaker() {
// Your microservice logic that might fail
}
public String fallbackMethod() {
return
"Fallback response
when the service is down";
}
}
In this example, the @HystrixCommand annotation applies a circuit breaker to the “serviceWithCircuitBreaker” method, and if it fails, it falls back to the “fallbackMethod.”
4. Explain how you would implement centralized logging and monitoring in a microservices architecture.
@RestController
public class LoggingController {
private Logger logger =
LoggerFactory.getLogger
(LoggingController.class);
@GetMapping("/log")
public String logExample() {
logger.info
("This is a log message.");
return "Logged a message!";
}
}
5. Write code to demonstrate the implementation of API Gateway in a microservices architecture using Spring Cloud Gateway.
@SpringBootApplication
public class ApiGatewayApplication {
public static void main(String[] args) {
SpringApplication.run
(ApiGatewayApplication.class, args);
}
@Bean
public RouteLocator customRouteLocator
(RouteLocatorBuilder builder) {
return builder.routes()
.route("service-route", r -> r
.path("/service/**")
.uri
("http://service-microservice")
)
.build();
}
}
6. Implement a simple RESTful microservice in Java using Spring Boot.
@RestController
@RequestMapping("/api")
public class GreetingController {
@GetMapping("/greeting")
public String greeting() {
return
"Hello from the microservice!";
}
}
7. Develop a microservice in Java that interacts with a database.
@RestController
@RequestMapping("/api")
public class UserController {
@Autowired
private UserRepository userRepository;
@GetMapping("/users")
public List<User> getAllUsers() {
return userRepository.findAll();
}
}
8. Implement caching in a Java microservice.
@Service
public class UserService {
@Autowired
private UserRepository userRepository;
@Cacheable("users")
public User getUserById(Long id) {
return userRepository.findById(id);
}
}
9. How do you implement logging and monitoring in Java-based microservices?
import org.apache.log4j.Logger;
public class LoggingExample {
final static Logger
logger = Logger.getLogger
(LoggingExample.class);
public static void main(String[] args) {
logger.debug("Debug message");
logger.info("Info message");
logger.warn("Warn message");
logger.error("Error message");
logger.fatal("Fatal message");
}
}
10. Implement security measures in a Java microservice.
@Configuration
@EnableWebSecurity
public class SecurityConfig extends
WebSecurityConfigurerAdapter {
@Override
protected void configure
(HttpSecurity http)
throws Exception {
http
.authorizeRequests()
.antMatchers("/api/secure/**")
.authenticated()
.anyRequest().permitAll()
.and()
.formLogin();
}
}
