Legacy-Systeme mit Microservices, Hystrix und RxJava modernisieren

WJAX, 4.November 2015 in München

Als Softwareentwickler ist man nur sehr selten in der Situation, ein völlig neues System auf der Basis neuester Technologien entwickeln zu dürfen. Oft sollen bestehende Systeme nur um viele kleinere Features erweitert werden. Die Renovierung der grundlegenden Systemarchitektur und die Einführung neuer Programmierparadigmen ist in diesem Umfeld schwierig. Umso wichtiger ist es, dass man die Modernisierung von Altsystemen zu einem fortlaufenden Bestandteil auch des featuregetriebenen Entwicklungsprozesses macht. In diesem Vortrag möchten wir zeigen, wie auch größere, monolithische Altsysteme mithilfe der offenen Netflix-Bibliotheken schrittweise in Richtung einer Microservice-Achitektur weiterentwickelt werden können. Hystrix kann dabei einen wertvollen Beitrag zur Gesamtstabilität des entstehenden verteilten Systems leisten. Der Einsatz von RxJava ist eine gute Möglichkeit, den Anteil von asynchronen Prozessen innerhalb der Legacy-Architektur zu erhöhen. Der Vortrag wird anhand von Beispielen demonstrieren, wie der hier angedeutete Modernisierungsprozess umgesetzt werden kann.

Transcript

1. Modernizing Systems with Microservices, Hystrix and RxJava Holger Kraus, Arne Landwehr W-JAX, München, Nov 4, 2015
2. A typical System
3. The context
4. Current problems > Maintenance is difficult > New features need a lot of time > Very unstable > Outdated technology > Doesn’t scale + frustrated developers :(
5. Current problems > Maintenance is difficult > New features need a lot of time > Very unstable > Outdated technology > Doesn’t scale Microservices FTW ! not yet …
6. Stabilize first!
7. External dependencies here! here! and also here!
8. Cascading Failures https://www.flickr.com/photos/benstassen/2991003141/
9. Stability patterns > Timeouts > Circuit Breaker > Bulkhead … Fail Fast, Steady State, Handshaking, Test Harness, Decoupling Middleware
10. Timeout https://www.flickr.com/photos/55293400@N07/15564061004
11. Bulkheads https://www.flickr.com/photos/10413717@N08/6935206524
12. Ships http://de.wikipedia.org/wiki/RMS_Titanic#/media/File:Titanic_Structure_de.svg
13. Bulkheads and IT > Thread pools > Database connection pools > Instances > Server > Data center
14. Circuit Breaker https://www.flickr.com/photos/leafbug/409950515/
15. Circuit Breaker http://martinfowler.com/bliki/CircuitBreaker.html
16. Hystrix > Library from Netflix > Resilience Library > Command Pattern > Metrics > Dashboard
17. Use Cases let’s pick this one!
18. Search Products 2. find external products 1. search products 3. find internal products 4. return internal + external products
19. Search Products
20. Call without Hystrix cascading failures incoming!
21. Simple Command
22. Execute it!
23. Execute it asynchronously
24. Fallback
25. In case Merchant 2 is down something is missing here
26. The stabilized system
27. Demo
28. And now?
29. Current Problems > Maintenance is difficult > New features need a lot of time > Very unstable => enables further distribution > Outdated technology > Doesn’t scale
30. Microservices! but how to get started ????
31. Architectural Decisions https://speakerdeck.com/aheusingfeld/microservices-meet-real-world-projects-lessons-learned
32. Domain Architecture which boxes do we need ? let the monolith guide you!
33. Domain: Search
34. Macro Architecture > Integration > Deployment > Formats > Protocols > Reduce Choices what’s the same for all boxes ? = API + UI = Docker = JSON = HTTP + AMQP = Java, Go Monozon: pick your own!
35. Micro Architecture Search Service
36. Migration Path ? pick one [big bang, strangler, wonder]
37. Big Bang a.k.a REVOLUTION only call old monolith meanwhile build new systems:
38. Big Bang only call new shiny systems delete this one!
39. Strangler a.k.a EVOLUTION your monolith a.k.a „Big Ball of Mud“
40. Strangler give your monolith internal structure and define interfaces … if possible.
41. Strangler Extract your new service and redirect calls to it
42. Strangler Once unused strangle the old code
43. Is it really so easy?
44. Time to connect boxes
45. Synchronous vs. Async/Parallel
46. Try this with futures blocking! blocking!
47. Time for RxJava > Reactive Extensions for the JVM > Asynchronous streams > Elements of > Iterator pattern > Observable pattern > Functional programming
48. https://speakerdeck.com/benjchristensen/functional-reactive-programming-with-rxjava-javaone-2013
49. Everything is a stream!
50. RxJava in one picture https://speakerdeck.com/benjchristensen/functional-reactive-programming-with-rxjava-javaone-2013
51. Creating Observables
52. Transforming with map http://reactivex.io/RxJava/javadoc/rx/Observable.html
53. map in action
54. Combining with merge http://reactivex.io/RxJava/javadoc/rx/Observable.html
55. merge in action
56. Combining streams with zip http://reactivex.io/RxJava/javadoc/rx/Observable.html
57. zip in action
58. Collecting details with flatMap http://reactivex.io/RxJava/javadoc/rx/Observable.html
59. flatMap in action
60. Why not map?
61. Concurrency
62. Easier with Hystrix
63. Converting into a stream
64. Returning a result
65. Summary > Use Hystrix to stabilize your system! > Use RxJava to increase the amount of async/ parallel processes in an easy way! > Introduce Microservices to get control over your system again! > Have fun :)
66. Our goal was to make you curious!
67. Find your own way!
68. Thank you! innoq.com