Microservice application learning

• API Gateway
• Eureka
• Hystrix

Tutorial Video

https://m.youtube.com/watch?v=nElpCWmpSew&list=PLyHJZXNdCXsd2e3NMW9sZbto8RB5foBtp&index=1

Estimated time: 105 minutes;

Create Database

CitizenService VaccinationCenter

Eureka Server Service

service name: EurekaServer url: http://localhost:8761/

remember to visit the url and check the Eureka page, you will see the service in that page

Dependency

org.springframework.cloud spring-cloud-starter-netflix-eureka-server

Configuration

server: port:
8761 eureka: client: fetch-registry: false register-with-eureka: false

Code

Only need to add @EnableEurekaServer

@SpringBootApplication @EnableEurekaServer public class EurekaServerApplication {

public static void main(String[] args) {
	SpringApplication.run(EurekaServerApplication.class, args);
}

}

Citizen Servie

VaccinationCenter Service

Enable CircuitBreaker and LoadBalanced

@SpringBootApplication @EnableCircuitBreaker public class VaccinationCenterApplication {

public static void main(String[] args) {
	SpringApplication.run(VaccinationCenterApplication.class, args);
}

@Bean
@LoadBalanced
public RestTemplate getRestTemplate() {
	return new RestTemplate();
}

}

Call another service

@RestController @RequestMapping("/vaccinationcenter") public class VaccinationCenterController { @Autowired private RestTemplate restTemplate;

@GetMapping("/id/{id}")
@HystrixCommand(fallbackMethod = "handleCitizenDownTime")
public ResponseEntity<RequiredResponse> getAllDataBasedonCenterId(@PathVariable Integer id) {

    RequiredResponse response = new RequiredResponse();
    //get vaccination center detail
    VaccinationCenter center = centerRepository.findById(id).get();
    response.setCenter(center);

    //then get all citizen registered in that center
    List<Citizen> listCitizen = restTemplate.getForObject("http://CITIZEN-SERVICE/citizen/id/" + id, List.class);
    response.setCitizens(listCitizen);
    return new ResponseEntity<RequiredResponse>(response, HttpStatus.OK);

}

public ResponseEntity<RequiredResponse> handleCitizenDownTime(@PathVariable Integer id) {

    RequiredResponse response = new RequiredResponse();
    //get vaccination center detail
    VaccinationCenter center = centerRepository.findById(id).get();
    response.setCenter(center);

    return new ResponseEntity<RequiredResponse>(response, HttpStatus.OK);
}

}