This document details the creation of Java microservices using Spring Boot and Spring Cloud, illustrating the setup of a discovery service and various microservices such as a car service and an API gateway. It provides code examples for configuring services, consuming APIs, and implementing features like circuit breaker and fallback mechanisms. Additionally, it mentions the use of JHipster for generating applications and highlights future enhancements for microservices development.

1. Java Microservices with Spring Boot and Spring Cloud
December 11, 2019
Matt Raible | @mraible
Photo by Trish McGinity https://www.mcginityphoto.com

3. Blogger on raibledesigns.com and
developer.okta.com/blog
Web Developer and Java Champion
Father, Husband, Skier, Mountain
Biker, Whitewater Rafter
Open Source Connoisseur
Hi, I’m Matt Raible!
Bus Lover
Okta Developer Advocate

6. Create Java Microservices using start.spring.io
http https://start.spring.io/starter.zip javaVersion==11
artifactId==discovery-service name==eureka-service
dependencies==cloud-eureka-server baseDir==discovery-service
| tar -xzvf -

7. Add JAXB for Java 11
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
</dependency>

8. Enable Eureka Server & Configure application.properties
server.port=8761
eureka.client.register-with-eureka=false
@EnableEurekaServer

9. Create Car Service
http https://start.spring.io/starter.zip
artifactId==car-service name==car-service baseDir==car-service
dependencies==actuator,cloud-eureka,data-jpa,h2,data-
rest,web,devtools,lombok | tar -xzvf -

10. Enable Discovery & Configure application.properties
server.port=8090
spring.application.name=car-service
@EnableDiscoveryClient

11. Create API Gateway
http https://start.spring.io/starter.zip
artifactId==api-gateway name==api-gateway baseDir==api-gateway
dependencies==cloud-eureka,cloud-feign,data-rest,web,cloud-
hystrix,lombok | tar -xzvf -

12. Enable Discovery & Configure application.properties
spring.application.name=api-gateway
@EnableDiscoveryClient

13. Build a REST API in Car Service
@Data
@NoArgsConstructor
@Entity
class Car {
public Car(String name) {
this.name = name;
}
@Id
@GeneratedValue
private Long id;
@NonNull
private String name;
}

14. Build a REST API in Car Service
@RepositoryRestResource
interface CarRepository extends JpaRepository<Car, Long> {
}

15. Build a REST API in Car Service
@Bean
ApplicationRunner init(CarRepository repository) {
return args -> {
Stream.of("Ferrari", "Jaguar", "Porsche", "Lamborghini",
"Bugatti", "AMC Gremlin", "Triumph Stag",
"Ford Pinto", "Yugo GV").forEach(name -> {
repository.save(new Car(name));
});
repository.findAll().forEach(System.out::println);
};
}

16. Consume Cars API in Gateway
@EnableFeignClients
@EnableCircuitBreaker
@EnableDiscoveryClient
@SpringBootApplication
public class ApiGatewayApplication {
public static void main(String[] args) {
SpringApplication.run(ApiGatewayApplication.class, args);
}
}

17. Consume Cars API in Gateway
@Data
class Car {
private String name;
}
@FeignClient("car-service")
interface CarClient {
@GetMapping("/cars")
@CrossOrigin
Resources<Car> readCars();
}

18. Consume Cars API in Gateway
@RestController
class CoolCarController {
private final CarClient carClient;
public CoolCarController(CarClient carClient) {
this.carClient = carClient;
}
// code on next slide
}

19. Consume Cars API in Gateway
private Collection<Car> fallback() {
return new ArrayList<>();
}
@GetMapping("/cool-cars")
@CrossOrigin
@HystrixCommand(fallbackMethod = "fallback")
public Collection<Car> goodCars() {
return carClient.readCars()
.getContent()
.stream()
.filter(this::isCool)
.collect(Collectors.toList());
}

20. Consume Cars API in Gateway
private boolean isCool(Car car) {
return !car.getName().equals("AMC Gremlin") &&
!car.getName().equals("Triumph Stag") &&
!car.getName().equals("Ford Pinto") &&
!car.getName().equals(“Yugo GV");
}

21. Start everything with ./mvnw

22. Access https://localhost:8080/cool-cars

23. Java Microservices with Spring Boot and Spring Cloud
developer.okta.com/blog/2019/05/22/java-microservices-spring-boot-spring-cloud

24. Java Microservices with Spring Cloud Config & JHipster
developer.okta.com/blog/2019/05/23/java-microservices-spring-cloud-config

25. Generated with JDL: Gateway
application {
config {
baseName gateway,
packageName com.okta.developer.gateway,
applicationType gateway,
authenticationType oauth2,
prodDatabaseType postgresql,
serviceDiscoveryType eureka,
testFrameworks [protractor]
}
entities Blog, Post, Tag, Product
}
jhipster.tech/jdl/#application_options

26. Generated with JDL: Blog with PostgreSQL
application {
config {
baseName blog,
packageName com.okta.developer.blog,
applicationType microservice,
authenticationType oauth2,
prodDatabaseType postgresql,
serverPort 8081,
serviceDiscoveryType eureka
}
entities Blog, Post, Tag
}

27. Generated with JDL: Store with MongoDB
application {
config {
baseName store,
packageName com.okta.developer.store,
applicationType microservice,
authenticationType oauth2,
databaseType mongodb,
devDatabaseType mongodb,
prodDatabaseType mongodb,
enableHibernateCache false,
serverPort 8082,
serviceDiscoveryType eureka
}
entities Product
}

28. Generated with JDL: Entities for Blog
entity Blog {
name String required minlength(3),
handle String required minlength(2)
}
entity Post {
title String required,
content TextBlob required,
date Instant required
}
entity Tag {
name String required minlength(2)
}

29. Generated with JDL: Entities for Store + Relationships
entity Product {
title String required,
price BigDecimal required min(0),
image ImageBlob
}
relationship ManyToOne {
Blog{user(login)} to User,
Post{blog(name)} to Blog
}
relationship ManyToMany {
Post{tag(name)} to Tag{post}
}

30. Generated with JDL: Pagination and Microservice
paginate Post, Tag with infinite-scroll
paginate Product with pagination
microservice Product with store
microservice Blog, Post, Tag with blog

31. Generated with JDL: Docker Compose
deployment {
deploymentType docker-compose
appsFolders [gateway, blog, store]
dockerRepositoryName "jmicro"
consoleOptions [zipkin]
}

32. JDL Studio

33. What’s Next for JHipster?
Full Reactive with WebFlux
and Spring Cloud Gateway
Spring Boot 2.2
GraphQL and Micro Frontends

34. JHipster Reactive Microservices in Alpha
github.com/jhipster/generator-jhipster/issues/7608

35. Reactive Microservices with Spring Cloud Gateway
developer.okta.com/blog/2019/08/28/reactive-microservices-spring-cloud-gateway

36. git clone https://github.com/oktadeveloper/okta-spring-webflux-react-
example.git
github.com/oktadeveloper/java-microservices-examples
Use the Source, Luke!

37. developer.okta.com/blog
@oktadev

38. Thanks!
Keep in Touch
raibledesigns.com
@mraible
Presentations
speakerdeck.com/mraible
Code
github.com/oktadeveloper
developer.okta.com