Thirty months of microservices. Stairway to heaven or highway to hell

1. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 1 @aahoogendoorn | www.ditisagile.nl Thirty months of microservices Stairway to heaven or highway to hell? Sander Hoogendoorn ditisagile.nl

2. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 2 Sander Hoogendoorn Me Dad, software architect, agile coach, programmer, trainer, speaker, writer Books, articles, conferences, courses Work Owner ditisagile.nl Former CTO insurance company Former global agile thoughtleader Capgemini Web www.sanderhoogendoorn.com aahoogendoorn aahoogendoorn sander@ditisagile.nl

3. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 3

4. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 5 @aahoogendoorn | www.ditisagile.nl Monoliths Hard to deliver, even harder to test and impossible to maintain

5. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 6 Who has a system that is too big and that really should be broken up?

6. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 8 Dependencies will kill you A typical systems landscape

7. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 9 @aahoogendoorn | www.ditisagile.nl A brief history of components and services

8. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 10 Client server

9. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 11 Component based development

10. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 12 Service oriented architecture

11. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 13 Microservices

12. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 15 @aahoogendoorn | www.ditisagile.nl Microservices Beyond the hype?

13. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 16 Microservices Beyond the hype?

14. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 17 Gartner hype cycle

15. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 18 @aahoogendoorn | www.ditisagile.nl Microservices The clear benefits

16. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 19 But first … a definition

17. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 20 In short, the microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. These services are built around business capabilities and independently deployable by fully automated deployment machinery. There is a bare minimum of centralized management of these services, which may be written in different programming languages and use different data storage technologies. Martin Fowler

18. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 22 In short, the microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. These services are built around business capabilities and independently deployable by fully automated deployment machinery. There is a bare minimum of centralized management of these services, which may be written in different programming languages and use different data storage technologies. Martin Fowler

19. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 29 Products not projects Scalable Decentralized governance Replaceable parts High performance Technology independent Polyglot persistence Easy to build Easy to test Easier deployment than monoliths Microservices Promises

20. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 30 What is a microservice exactly? How small is a microservice? Requirements in a microservice world Components or services Who owns a microservice? What technologies do you use? What protocols do you apply? How to define messages How to test microservices How to coordinate when business services run across components? How to build deployment pipelines? How does integration really work? Containers anyone? Microservices But…

21. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 31 Opinions, opinions, opinions

22. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 32 Oh and by the way… Doing microservices means that you are building a distributed system

23. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 33 @aahoogendoorn | www.ditisagile.nl Are microservices a stairway to heaven?

24. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 34 @aahoogendoorn | www.ditisagile.nl Or are they a highway to hell?

25. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 35 @aahoogendoorn | www.ditisagile.nl From the trenches Microservices in real life

26. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 36 Where do we come from?

29. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 39 Outsourcing didn’t work

30. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 40 Where are we going to?

32. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 45 For the things we have to learn before we can do them, we learn by doing themAristotle

34. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 47 @aahoogendoorn | www.ditisagile.nl So what did we learn?

35. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 48 Microservices require an evolutionary software architecture

36. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 49 @aahoogendoorn | www.ditisagile.nl Start with some guiding principles

37. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 51 Client thinks in business processes, so we implement business processes We move away from the mainframe, to a new systems landscape, consisting of micro-applications and micro- components Requirements and documentation are modeled rather than written Applications implement a single (elementary) business process Components serve a single purpose and offer services Applications and components all have their own bounded context – a domain model Applications and components will have an similar internal software architecture to facilitate ease of maintenance and allow for harvesting re-use Communication between applications and components will use a simple open protocol - REST Some guiding principles

38. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 52 Client thinks in business processes, so we implement business processes We move away from the mainframe, to a new systems landscape, consisting of micro-applications and micro- components Requirements and documentation are modeled rather than written Applications implement a single (elementary) business process Components serve a single purpose and offer services Applications and components all have their own bounded context – a domain model Applications and components will have an similar internal software architecture to facilitate ease of maintenance and allow for harvesting re-use Communication between applications and components will use a simple open protocol - REST Some guiding principles

41. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 64 @aahoogendoorn | www.ditisagile.nl Designing microservices Modular design and bounded contexts

42. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 65 Doing big up-front design is dumb, doing no design up-front is even dumberDave Thomas

43. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 66 Bounded contexts

44. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 67 SOLID Single Responsibility Principle Open Closed Principle Liskov Substitution Principle Interface Segregation Principle Dependency Inversion Principle Single Responsibility Principle Every “module” should have responsibility over a single part of the functionality provided by the software, That responsibility should be entirely encapsulated by that module All its services should be narrowly aligned with that responsibility The SOLID principles Uncle Bob Martin

45. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 68 Single responsibility principle Group together things that change together Separate things that change for different reason

46. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 69 Domain driven design The paradigm of designing software based on models of the underlying domain The domain model helps the business and the developers to reason about the functionality A model needs to be unified – internally consistent without contradictions Bounded context The bounded context is a central pattern in domain driven design When you model larger domains, it becomes progressively harder to create this single unified model So, instead of creating a single unified model, you create several, all valid within their bounded context Bounded context Eric Evans

47. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 70 The single unified domain model Or more often the humongous data model

48. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 71 Bounded contexts

50. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 73 @aahoogendoorn | www.ditisagile.nl Modeling resources

51. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 75 Root resource (component) GET the collection, but only limited to this representation (but with locations likely) GET a single item from the collection, but with representation Modeling resources

53. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 77 @aahoogendoorn | www.ditisagile.nl RESTfulness is not as easy as it seems

54. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 78 A small quiz Guess the HTTP status codes… Get localhost:8080/countries Get localhost:8080/countries/42 localhost:8080/countries/GRC localhost:8080/countries/isocode/GRC localhost:8080/countries?isocode=“GRC” Post or put? localhost:8080/countries localhost:8080/countries/38

55. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 84 HTTP return codes cheat sheet 1**. Hold on 2**. Here you go 3**. Go away 4**. You fucked up 5**. I fucked up

56. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 85 Be conservative in what you send, be liberal in what you accept Postel’s Law

57. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 87 @aahoogendoorn | www.ditisagile.nl Testing microservices

58. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 88 Fail fast, fail often, fail forward

59. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 89 A (typical) service development lifecycle

60. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 90 What to test

61. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 91 Even though you might have really brilliant testers…

62. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 92 … please automate all your tests

63. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 95 @aahoogendoorn | www.ditisagile.nl Deploying microservices Continuous integration and build pipelines

64. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 99 Microservices. Building a deployment pipeline Code DeveloperTest Test AcceptanceTest Acceptance Live Code DeveloperTest Test AcceptanceTest Acceptance Live Code DeveloperTest Test AcceptanceTest Acceptance Live Code DeveloperTest Test AcceptanceTest Acceptance Live

65. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 100 Microservices. Pipeline hell? Codev.2 DeveloperTestv.2 Testv.2 AcceptanceTestv.2 Acceptancev.2 Code DeveloperTest Test AcceptanceTest Acceptance Live Testv.2 AcceptanceTestv.2 Acceptancev.2 Livev.2 DeveloperTest Test AcceptanceTest Acceptance Live Codev.3 DeveloperTestv.3 Live Codev.2

66. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 101 No one tool to rule them all We tried Jenkins, Bamboo, Team City, GoCD and then Jenkins again…

67. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 102 DevOps is not easy It feels like showing up at the wrong re-enactment

68. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 131 @aahoogendoorn | www.ditisagile.nl In retrospective Some final thoughts

69. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 132 Microservices are not for everyone (yet) How do we benefit from implementing microservices?

70. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 133 Will it work?

71. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 134 The hockey stick model

72. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 135 Minimal viable product

74. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 137 @aahoogendoorn | www.ditisagile.nl Allow your teams to learn continuously…

75. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 138 @aahoogendoorn | www.ditisagile.nl And never forget to have fun

76. @aahoogendoorn | www.ditisagile.nlThirty months of microservices. Stairway to heaven or highway to hell? 139 @aahoogendoorn | www.ditisagile.nl References and questions www.sanderhoogendoorn.com www.ditisagile.nl aahoogendoorn aahoogendoorn sander@ditisagile.nl