Spring Boot makes creating small Java application easy - and also facilitates operations and deployment. But for Microservices need more: Because Microservices are a distributed systems issues like Service Discovery or Load Balancing must be solved. Spring Cloud adds those capabilities to Spring Boot using e.g. the Netflix stack. This talks covers Spring Boot and Spring Cloud and shows how these technologies can be used to create a complete Microservices environment.

1. Microservices with
Java, Spring Boot &
Spring Cloud
Eberhard Wolff
Fellow, innoQ
@ewolff

3. http://microservices-buch.de/ http://microservices-book.com/

4. http://microservices-book.com/primer.html
FREE!!!!

5. Microservice
Definition

6. Server Server
Microservices:
Definition
> Small
> Independent deployment units
> Any technology
> Any infrastructure
Micro
Service
Micro
Service

7. Components Collaborate
Micro
Service
Micro
Service
Link
Data Replication
REST
Messaging

8. Infrastructure
> …must support lots of services
> Easy to create a new project
> REST integrated
> Messaging supported
> Uniform operations

9. Spring Boot Demo

10. Simple Infrastructure
> One pom.xml
> …or Gradle / Ant
> Very few dependencies
> One plug in
> Versions defined

11. REST Integrated
> Support in Spring MVC
> As we have seen
> Also: JAX-RS
> Jersey

12. Messaging Support
> Numerous Spring Boot Starter
> AMQP (RabbitMQ)
> HornetQ (JMS)
> ActiveMQ Artemis (JMS)

13. Messaging Support
> Spring JMS abstraction
> Message driven POJOs
> Scalable
> Simplify sending JMS
> Can use other libs, too!
> Boot: everything Spring / Java can do

14. Infrastructure
> …must support lots of services
> Easy to create a new project
> REST integrated
> Messaging supported
> Simple deployment
> Uniform operations
✓
✓
✓

15. Deploy
> Package everything in an
executable JAR
> …or a WAR
> Based on Maven, Ant or Gradle
> Add configuration

16. Spring Boot
Deploy Demo

17. Deploy
> Install a basic machine
> Install Java
> Copy over JAR
> Optional: Make it a Linux Service
> …just a link
> Optional: Create application.properties

18. Infrastructure
> …must support lots of services
> Easy to create a new project
> REST integrated
> Messaging supported
> Simple deployment
> Uniform operations
✓
✓
✓
✓

19. Spring Boot Actuator
> Provide information about the application
> Via HTTP / JSON
> …or Metrics
> Can be evaluated by monitoring tools etc.
> E.g. Graphite, Grafana ….

20. Spring Boot
Actuator Demo

21. > https://github.com/ewolff/user-registration-V2
> Logging ELK
> Subdir log-analysis
> Monitoring Graphite
> Subdir graphite

22. Infrastructure
> …must support lots of services
> Easy to create a new project
> REST integrated
> Messaging supported
> Simple deployment
> Uniform operations
✓
✓
✓
✓
✓

23. Spring Cloud

24. Based on Spring Boot

25. Supports many
technology stacks,
Clouds,
…

26. Focus: Netflix Stack

27. Spring Cloud
Netflix
Zuul
Routing
Ribbon
Client Side
Load Balancing
Eureka
Service Discovery
Hystrix
Resilience

28. Coordinating
Microservices

29. > Must find each other
Microservice Microservice

30. Service Discovery
Eureka

31. Why Eureka?
> REST based service registry
> Supports replication
> Caches on the client
> Resilient
> Fast
> …but not consistent
> Foundation for other services

32. Eureka Client in
Spring Cloud
> @EnableDiscoveryClient:
generic
> @EnableEurekaClient:
more specific
> Dependency to
spring-cloud-starter-eureka
> Automatically registers application

33. application.properties
eureka.client.serviceUrl.defaultZone=http://host:8761/eureka/
eureka.instance.leaseRenewalIntervalInSeconds=5
spring.application.name=catalog
eureka.instance.metadataMap.instanceId=${spring.application.name}:${r
andom.value}
eureka.instance.preferIpAddress=true
Eureka server
Can include user / password
Needunique ID
Load balancing
Faster updates
Dockerwon’t resolve host names
Used for registration
In CAPITAL caps

34. Eureka Server
@EnableEurekaServer
@EnableAutoConfiguration
public class EurekaApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaApplication.class,
args);
}
}
Add dependency to
spring-cloud-starter-eureka-server

36. > Must find each other
> Route calls to a service
Microservice Microservice

37. Zuul
Routing

38. Routing
> One URL to the outside
> Internal: Many Microservices
> In particular: REST
> Power through filters

39. Customer Order Catalog
Zuul
Proxy
Automatically maps route to server registered on Eureka
i.e. /customer/**
to CUSTOMER
No configuration
Can add filters etc

40. Zuul Proxy
@SpringBootApplication
@EnableZuulProxy
public class ZuulApplication {
public static void main(String[] args) {
new SpringApplicationBuilder(ZuulApplication.class).
web(true).run(args);
}
}
Enable Zuul Proxy
Can change route
Also routing to external services possible

41. > Must find each other
> Route calls to a service
> Configuration
Microservice Microservice

42. Spring Cloud Config

43. Configuration
> Spring Cloud Config
> Central configuration
> Dynamic updates
> Can use git backend
> I prefer immutable server
> & DevOps tools (Docker, Chef…)

44. Spring Cloud Bus
> Pushed config updates
> …or individual message
> I prefer a messaging solution
> Independent from Spring

45. > Must find each other
> Route calls to a service
> Configuration
> Security
Microservice Microservice

46. Spring Cloud Security

47. Spring Cloud Security
> Single Sign On via OAuth2
> Forward token e.g. via RestTemplate
> Support for Zuul
> Very valuable!

48. Implementing
Microservices

49. Microservice Microservice
> Load Balancing

50. Load Balancing
Ribbon

51. Proxy Load Balancing
> Centralized Load Balancing
> Can become bottle neck
> Single point of failure
> Configuration complex
Load
Balancer
Server
Client

52. Client
Ribbon: Client Side
Load Balancing
> Decentralized Load Balancing
> No bottle neck
> Resilient
> Can consider response time
> Data might be inconsistent
Load
Balancer
Server

53. RestTemplate & Load
Balancing
@RibbonClient(name = "ribbonApp")
…
public class RibbonApp {
@Autowired
private RestTemplate restTemplate;
public void callMicroService() {
Store store = restTemplate.
getForObject("http://stores/store/1",
Store.class);
}
Enable Ribbon
Left out other annotations
Eureka name or server list
Standard Spring
REST client
Can also use Ribbon API

54. Microservice Microservice
> Load Balancing
> Resilience

55. Hystrix
Resilience

56. Hystrix
> Enable resilient applications
> Do call in other thread pool
> Won’t block request handler
> Can implement timeout

57. Hystrix
> Circuit Breaker
> If call system fail open
> If open do not forward call
> Forward calls after a time window
> System won’t be swamped with requests

58. Hystrix / Spring Cloud
> Annotation based approach
> Annotations of javanica libraries
> Java Proxies automatically created
> Simplifies Hystrix dramatically
> No commands etc

59. @HystrixCommand(fallbackMethod = "getItemsCache")
public Collection<Item> findAll() {
…
this.itemsCache = pagedResources.getContent();
return itemsCache;
}
private Collection<Item> getItemsCache() {
return itemsCache;
}
Fallback

60. Stream via http
Circuit Breaker status
Thread Pool status

61. Conclusion

62. Infrastructure
> Easy to create a new project
> REST integrated
> Messaging supported
> Simple deployment
> Uniform operations

63. Spring Cloud
> Eureka: Service Discovery
> Zuul: Route calls to a service
> Spring Cloud Config: Configuration
> Ribbon: Load Balancing
> Hystrix: Resilience

64. Links
> https://github.com/ewolff/microservices
> https://github.com/ewolff/spring-boot-demos
> https://github.com/ewolff/user-registration-V2
> http://projects.spring.io/spring-boot/
> http://projects.spring.io/spring-cloud
> https://spring.io/guides/
> http://microservices-book.com

65. Thank You!!
@ewolff