This presentation show several options how to implement microservices: the Netflix stack, Consul, and Kubernetes. Also integration options like REST and UI integration are covered.

1. Microservices –
Implementations not
only with Java
Eberhard Wolff
http://ewolff.com
@ewolff
Fellow

2. http://continuous-delivery-buch.de/ http://continuous-delivery-book.com/

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

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

5. What are
Microservices?
> Modules providing interfaces
> Processes, Containers, virtual machines
> Standardized communication:
Synchronous, asynchronous, or UI integration
> Macro- and Micro-Architecture
i.e. clearly defined common, and specific decisions

6. What are
Microservices?
> Independent Continuous Delivery Pipeline including
tests
> Standardized Operations
(configuration, log analysis, tracing, monitoring,
deployment)
> Standards on the interface level
e.g. not a specific log library
> Resilient (compensate failure, crashes …)
therefore separate processes, VM, Docker containers

7. Microservices =
Extreme Decoupling

8. Operational
Complexity
Extreme
Decoupling

9. Micro
Service
Micro
Service
Link
Sync
Async

10. Synchronous REST
Microservices

11. Customer Order Catalog
REST
internal
HTTP
external

12. Synchronous Microservices
> Service Discovery:
IP / port?
> Load Balancing:
Resilience and independent scaling
> Routing:
Route external request to microservices
> Resilience

13. Synchronous
Microservices with
Java, Spring Boot /
Cloud & the Netflix
Stack

14. https://github.com/
ewolff/microservice

15. Service Discovery
Eureka

16. Why Eureka for Service
Discovery?
> REST based service registry
> Supports replication
> Caches on the client
> Resilient
> Fast
> Foundation for other services

17. Eureka Client
> @EnableDiscoveryClient:
generic
> @EnableEurekaClient:
specific
> Dependency on
spring-cloud-starter-eureka
> Automatically registers application

18. 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

20. Load Balancing
Ribbon

21. Client
Ribbon: Client Side
Load Balancing
> Decentralized Load Balancing
> No bottle neck
> Resilient
Load
Balancer
Server

22. Ribbon Example
private LoadBalancerClient loadBalancer;
…
ServiceInstance instance = loadBalancer.choose("CATALOG");
String url = "http://" + instance.getHost() + ":”
+ instance.getPort() + "/catalog/";
Via Dependency Injection
Eureka name
Need dependency to spring-cloud-starter-ribbon

23. Resilience

24. Timeout
> Do call in other thread pool
> Won’t block request handler
> Can implement timeout

25. Circuit Breaker
> Called system fails -> open
> Open -> do not forward call
> Forward calls after a time window

26. Hystrix
Configuration
> Failure Percentage
> Time window until open configurable
> Time window to reject requests
> …
> https://github.com/Netflix/Hystrix/wiki/Con
figuration

27. Hystrix &
Spring Cloud
> Annotation based approach
> Annotations of javanica libraries
> Simplifies Hystrix
> No commands

28. @SpringBootApplication
@EnableDiscoveryClient
@EnableCircuitBreaker
public class OrderApp {
public static void main(String[] args) {
SpringApplication.run(OrderApp.class, args);
}
}
Enable Hystrix
Need spring-cloud-starter-hystrix

29. @HystrixCommand(fallbackMethod = "getItemsCache",
commandProperties = { @HystrixProperty(name =
"circuitBreaker.requestVolumeThreshold", value = "2") } )
public Collection<Item> findAll() {
…
this.itemsCache = pagedResources.getContent();
return itemsCache;
}
private Collection<Item> getItemsCache() {
return itemsCache;
}
Fallback

30. Zuul
Routing

31. Routing
> One URL to the outside
> Internal: Many Microservices
> REST
> Or HTML GUI
> Hides internal structure (sort of)
> Might add filters

32. Customer Order Catalog
Zuul
Proxy
Automatically maps route to server registered on Eureka
i.e. /customer/**
to CUSTOMER
No configuration

33. Netflix Stack
> Service Discovery: Eureka
> Load Balancing: Ribbon
> Routing: Zuul
> Resilience: Hystrix
> Non-Java microservice:
specific clients or sidecar

34. Consul
> Service Discovery by Hashicorp
> DNS interface
> Platform independent
> Consul Template can fill out config file
templates
> e.g. for load balancer
> …unaware of service discovery

35. https://github.com/
ewolff/microservice-consul

36. Kubernetes

37. https://github.com/
ewolff/microservice-
kubernetes

38. Kubernetes
> Docker container on a single machine:
Not resilient enough
> Kubernetes: Run Docker container in cluster
> …and much more!

39. Pods
> Kubernetes runs Pods
> Pods = 1..n Docker containers
> Shared volumes
> …and ports

40. Replica Sets
> Deployment creates replica set
> Replica sets ensure that a certain number of
Pods run
> ...for load balancing / fail over

41. Services
> Services ensure access to the Pods
> DNS entry
> Cluster-wide unique IP address for internal
access
> External load balancer for external access

42. Replica Set
Pod
Pod
Service
starts
DNS
Cluster IP
address
Load Balancer
Deployment
creates

43. Load Balancer
Kubernetes Cluster Server
Service 1
Service 2
Kubernetes Cluster Server
Service 1
Service 2Service
adds a load
balancer
Load Balancer
(e.g. Amazon
Elastic
Load Balancer)

44. Kubernetes
> Service Discovery: DNS
> Load Balancing: IP
> Routing: Load Balancer or Node Port
> Resilience: Hystrix? envoy proxy?
> Can use any language

45. No code
dependencies on
Kubernetes!

46. UI Integration

47. UI Integration
> Very powerful
> Often overlooked
> UI should be part of a microservices
> Self-contained System emphasize UI
> http://scs-architecture.org/

48. Hyperlinks to navigate between
systems.
System 1 System 2

49. Transclusion of content served
by another application
System 1 System 2

50. https://www.innoq.com/
en/blog/transclusion/

51. Server-side integration
> Centralized aggregation
> Bottleneck (runtime/development time)
Browser
UI 1
UI 2
Frontend
Server
Backend 1
Backend 2

52. Server-side Integration:
Technologies
> ESI (Edge Side Include)
> E.g. Varnish cache
> SSI (Server Side Include)
> E.g. Apache httpd, Nginx

53. ESI (Edge Side Includes)
...
<header>
... Logged in as: Ada Lovelace ...
</header>
...
<div>
... a lot of static content and images ...
</div>
...
<div>
some dynamic content
</div>

54. ESI (Edge Side Includes)
...
<esi:include src="http://example.com/header" />
...
<div>
... a lot of static content and images ...
</div>
...
<esi:include src="http://example.com/dynamic" />
http://www.w3.org/TR/esi-lang

55. https://github.com/
ewolff/SCS-ESI

56. Client-side integration
Browser
UI 1
UI 2
Backend 1
Backend 2

57. Client-side Integration:
Code
$("a.embeddable").each(function(i, link) {
$("<div />").load(link.href, function(data, status, xhr) {
$(link).replaceWith(this);
});
});
Replace <a href= " " class= "embeddable">
with content of document in a <div> (jQuery)

58. Transclusion
> Tighter coupling than links
> …but still very loose
> Common CSS
> (Avoid) common JavaScript
> Layout
> Look & Feel

59. https://github.com/
ewolff/SCS-jQuery

60. https://github.com/
ewolff/
crimson-assurance-demo

61. Conclusion

62. Operational
Complexity
Extreme
Decoupling

63. Conclusion:
Communication
> Netflix: Java focus, code dependencies
> Kubernetes: No code dependencies
> UI Integration more decoupling

64. Links
> List of microservices demos (sync, async, UI):
http://ewolff.com/microservices-demos.html
> REST vs. Messaging for Microservices
https://www.slideshare.net/ewolff/rest-vs-
messaging-for-microservices

65. EMail jugsaxony2017@ewolff.com to get:
Slides
+ Microservices Primer
+ Sample Microservices Book
+ Sample of Continuous Delivery Book
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