Modernizing systems with Microservices, Hystrix and RxJava

This Talk was given at the JEEConf in Kiev, 23th May 2015

As a software developer you are not very often in the situation where you develop a completely new system from scratch based on recent techonologies. More often just small features have to be integrated in already existing systems. A change of the basic software architecture and an introduction of new programming paradigms are very difficult in this context. It is all the more important to make the modernization of a legacy systems an ongoing part of the feature-driven development process. In this talk I will show step by step how to transform a big, monolithic legacy system towards a modern microservice based architecture. And I will demonstrate how two open libraries from Netflix can support this process. Hystrix will help us to improve the overall stability of the system and RxJava will help us to handle asynchronous processes in a more elegant way. Based on examples I will show how the suggested modernization process could be realised.

Transcript

1. Wir lösen das – persönlich! Modernizing systems with Microservices, Hystrix and RxJava Holger Kraus JEEConf, Kiev, May 23, 2015 !
2. © 2015 innoQ Deutschland GmbH A typical system
3. © 2015 innoQ Deutschland GmbH The context
4. © 2015 innoQ Deutschland GmbH Current problems ‣ Maintenance is difficult ‣ New features need a lot of time ‣ Very unstable ‣ Outdated technology ‣ Doesn’t scale ‣ Frustrated developers
5. © 2015 innoQ Deutschland GmbH Stabilize first!
6. © 2015 innoQ Deutschland GmbH External dependencies
7. © 2015 innoQ Deutschland GmbH Cascading Failures https://www.flickr.com/photos/benstassen/2991003141/
8. © 2015 innoQ Deutschland GmbH Stability patterns ‣ Timeouts ‣ Circuit Breaker ‣ Bulkheads ! 
 … Fail Fast, Steady State , Handshaking, Test Harness, Decoupling Middleware
9. © 2015 innoQ Deutschland GmbH Timeout https://www.flickr.com/photos/55293400@N07/15564061004
10. © 2015 innoQ Deutschland GmbH Bulkheads https://www.flickr.com/photos/10413717@N08/6935206524
11. © 2015 innoQ Deutschland GmbH Ships http://de.wikipedia.org/wiki/RMS_Titanic#/media/File:Titanic_Structure_de.svg
12. © 2015 innoQ Deutschland GmbH Bulkheads and IT ‣ Thread pools ‣ Database connection pools ‣ Instances ‣ Server ‣ Data center
13. © 2015 innoQ Deutschland GmbH Circuit Breaker https://www.flickr.com/photos/leafbug/409950515/
14. © 2015 innoQ Deutschland GmbH Circuit Breaker http://martinfowler.com/bliki/CircuitBreaker.html
15. © 2015 innoQ Deutschland GmbH ‣ Library from Netflix ‣ Resilience Library ‣ Command Pattern ‣ Metrics ‣ Dashboard Hystrix
16. © 2015 innoQ Deutschland GmbH Call without Hystrix
17. © 2015 innoQ Deutschland GmbH Simple Command
18. © 2015 innoQ Deutschland GmbH Execute it!
19. © 2015 innoQ Deutschland GmbH Execute it asynchronously
20. © 2015 innoQ Deutschland GmbH Fallback
21. © 2015 innoQ Deutschland GmbH The stabilized system
22. © 2015 innoQ Deutschland GmbH Demo
23. © 2015 innoQ Deutschland GmbH And now?
24. © 2015 innoQ Deutschland GmbH Current problems ‣ Maintenance is difficult ‣ New features need a lot of time ‣ Very unstable ‣ Outdated technology ‣ Doesn’t scale ‣ Frustrated developers
25. © 2015 innoQ Deutschland GmbH https://www.flickr.com/photos/donmaedi/116013352
26. © 2015 innoQ Deutschland GmbH Monozon is a typical Monolith ‣ hidden dependencies ‣ module boundaries are not clear ‣ distributed business processes ‣ just one technical platform ‣ Everything depends on everything
27. © 2015 innoQ Deutschland GmbH We need a clear cut! https://www.flickr.com/photos/taefit/8528632756
28. © 2015 innoQ Deutschland GmbH Our mission: Creating smaller systems that are ‣ understandable ‣ enhanceable ‣ have clear boundaries and responsibilities ‣ allow technological diversity
29. © 2015 innoQ Deutschland GmbH The typical cut
30. © 2015 innoQ Deutschland GmbH Vertical Services, one UI
31. © 2015 innoQ Deutschland GmbH Self contained Systems
32. © 2015 innoQ Deutschland GmbH Micro architecture ‣ Separate (redundant) persistence ‣ Internal, separate logic ‣ Domain models & implementation strategies ‣ Separate UI ‣ Separate development and evolution ‣ Separate deployment, separate infrastructure ‣ Limited interaction with other systems
33. © 2015 innoQ Deutschland GmbH Domain architecture ‣ System boundaries reflect business dependencies ‣ defines who is responsible for which data ‣ follows the principle of ‣ loose coupling ‣ high cohesion
34. © 2015 innoQ Deutschland GmbH From internal structure
35. © 2015 innoQ Deutschland GmbH To autonomous systems
36. © 2015 innoQ Deutschland GmbH Ask the monolith ‣ identify Bounded Contexts ‣ define boundaries explicitly ‣ The experience with the monolith helps to create clear system boundaries
37. © 2015 innoQ Deutschland GmbH Connect! https://www.flickr.com/photos/npobre/8189066572
38. © 2015 innoQ Deutschland GmbH Macro architecture ‣ defines standards across systems ‣ UI integration ‣ communication protocols ‣ representation formats ‣ data redundancy ‣ logging, monitoring, security
39. © 2015 innoQ Deutschland GmbH Smart endpoints, dump pipes! http://martinfowler.com/articles/microservices.html Martin Fowler, James Lewis
40. © 2015 innoQ Deutschland GmbH Consequences ‣ Transactions contexts are bound to just one system ‣ Data should be just changed by the systems that are responsible for it ‣ Processes need Data that are spread over various systems
41. © 2015 innoQ Deutschland GmbH Connecting data
42. © 2015 innoQ Deutschland GmbH Synchronous vs. Asynchronous
43. © 2015 innoQ Deutschland GmbH Time for RxJava! ‣ Reactive Extensions for the JVM ‣ Asynchronous streams ‣ Elements of ‣ Iterator patter ‣ Observable pattern ‣ Functional programming
44. © 2015 innoQ Deutschland GmbH https://speakerdeck.com/benjchristensen/functional-reactive-programming-with-rxjava-javaone-2013
45. © 2015 innoQ Deutschland GmbH RxJava in one picture https://speakerdeck.com/benjchristensen/functional-reactive-programming-with-rxjava-javaone-2013
46. © 2015 innoQ Deutschland GmbH Create streams
47. © 2015 innoQ Deutschland GmbH Transforming with map http://reactivex.io/RxJava/javadoc/rx/Observable.html
48. © 2015 innoQ Deutschland GmbH map in action
49. © 2015 innoQ Deutschland GmbH Combining with merge http://reactivex.io/RxJava/javadoc/rx/Observable.html
50. © 2015 innoQ Deutschland GmbH merge in action
51. © 2015 innoQ Deutschland GmbH Collecting details with flatMap http://reactivex.io/RxJava/javadoc/rx/Observable.html
52. © 2015 innoQ Deutschland GmbH Combining streams with zip http://reactivex.io/RxJava/javadoc/rx/Observable.html
53. © 2015 innoQ Deutschland GmbH flatMap and zip in action
54. © 2015 innoQ Deutschland GmbH Subscribe to stream
55. © 2015 innoQ Deutschland GmbH Blocking streams
56. © 2015 innoQ Deutschland GmbH Systems connected
57. © 2015 innoQ Deutschland GmbH How could you start? https://www.flickr.com/photos/epemsl/8790814488
58. © 2015 innoQ Deutschland GmbH My goal was to make you curious!
59. © 2015 innoQ Deutschland GmbH Find your own way!
60. © 2015 innoQ Deutschland GmbH Summary ‣ Use Hystrix to stabilize your system! ‣ Use RxJava to increase the amount of asynchronous processes in an easy way! ‣ Introduce Microservices to get control over your system again!
61. © 2015 innoQ Deutschland GmbH Thank you! holger.kraus@innoq.com Twitter: @old_nobody