How can microservice can talk to other microservice in JHipster - jhipster

Question

I am planning to create a microservice aplication with a dedicated service for dealing with data (mostly a Mongodb based service). I am wondering if there is a way using which my other microservices will be able to communicate with this service to make use of the shared data. Is it possible with JHipster API Gateway ?
If not how can I achieve this. I dont want to keep multiple copies of the same data within each microservice.

Answer 1

You can also use Feign clients with JHipster.
Annotate your SpringBootApplication with #EnableFeignClients
...
import org.springframework.cloud.openfeign.EnableFeignClients;
...
#SpringBootApplication
#EnableConfigurationProperties({LiquibaseProperties.class, ApplicationProperties.class})
#EnableDiscoveryClient
#EnableFeignClients
public class MyApp {
...
}
Create a Feign client in your microservice
...
import org.springframework.cloud.openfeign.FeignClient;
...
#FeignClient("another-service")
public interface AnotherClient {
#RequestMapping(method = RequestMethod.GET, value = "/api/another")
List<AnotherDTO> getAll();
}
Inject the Feign client with #Autowired and call it. It should be ready to use.
#RestController
#RequestMapping("/api")
public class MyResource {
...
#Autowired
private AnotherClient anotherClient;
...
#GetMapping("/another")
#Timed
public List<AnotherDTO> getAll() {
log.debug("REST request to get all");
return anotherClient.getAll();
}
}
For us, it worked without implementing a ClientHttpRequestInterceptor and setting a JWT token.

Answer 2

You can register your microservices to the same registry and then they can call each other.
UPDATE : Here is how I made it work.
In the microservice consuming the data one, use RestTemplate with the current user's jwt-token in the Authorization-header for the API calls :
#Component
public class AuthenticateClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {
#Override
public ClientHttpResponse intercept(HttpRequest httpRequest, byte[] bytes, ClientHttpRequestExecution clientHttpRequestExecution) throws IOException {
String token = SecurityUtils.getCurrentUserJWT();
httpRequest.getHeaders().add("Authorization","Bearer "+token);
return clientHttpRequestExecution.execute( httpRequest, bytes );
}
}
My custom restTemplate using ClientHttpRequestInterceptor for adding token in header.
#Configuration
public class CustomBean {
#Autowired
AuthenticateClientHttpRequestInterceptor interceptor;
#Bean
#LoadBalanced
public RestTemplate restTemplate() {
RestTemplate restTemplate = new RestTemplate();
restTemplate.setInterceptors(Collections.singletonList(interceptor));
return restTemplate;
}
}
And in the resource controller where your are making the call for data:
#RestController
#RequestMapping("/api")
public class DataResource {
#Autowired
RestTemplate restTemplate;
#PostMapping("/hello")
#Timed
public ResponseEntity<Hello> createHello(#RequestBody Hello Hello) throws URISyntaxException {
//The name your data micro service registrated in the Jhipster Registry
String dataServiceName = "data_micro_service";
URI uri = UriComponentsBuilder.fromUriString("//" + dataServiceName + "/api/datas")
.build()
.toUri();
//call the data microservice apis
List<Data> result = restTemplate.getForObject(uri, Data[].class);
return ResponseEntity.created(new URI("/api/hellos/" + result.getId()))
.headers(HeaderUtil.createEntityCreationAlert(ENTITY_NAME, result.getId().toString()))
.body(result);
}
}

Answer 3

Typically microservices talk to each other. Thats the whole point. With Eureka discovery in place you simply call the microservice by name instead of the FQDN which we normally would use without microservice.
For e.g. your book-service will call the author-service like this
http://author-service/authors
full example here https://spring.io/blog/2015/01/20/microservice-registration-and-discovery-with-spring-cloud-and-netflix-s-eureka
Please don't forget that JHipster is an opinionated framework based off of Spring Cloud so you can find most of this stuff by searching Spring docs.

Answer 4

you can use below solution :
Microservice A (i.e UAA-SERVICE), and Microservice B
Microservice B want to connect microservice A and call services with Feign client.
1)This code for Microservice B
Client proxy :- #AuthorizedFeignClient(name = "UAA-SERVICE")
#AuthorizedFeignClient(name = "UAA-SERVICE")
public interface UaaServiceClient {
#RequestMapping(method = RequestMethod.GET, path = "api/users")
public List<UserDTO> getUserList();
#RequestMapping(method = RequestMethod.PUT, path = "api/user-info")
public String updateUserInfo(#RequestBody UserDTO userDTO);
}
UAA-SERVICE : find this name with running Application Instances with registry.
2) In Microservice B (application.yml)
Increase feign client connection Time Out:
feign:
client:
config:
default:
connectTimeout: 10000
readTimeout: 50000
Increase hystrix Thread time out:-
hystrix:
command:
default:
execution:
isolation:
thread:
timeoutInMilliseconds: 60000
shareSecurityContext: true
3) add #EnableFeignClients in main #SpringBootApplication class.
This solution is working fine for me.