Slides from ClojuTRE 2012 talk: https://clojutre.org/2012/

1. Clojure in real life project
Tommi Reiman (@ikitommi)

2. :what

3. :what
Self service project for the public sector

4. :how

5. :how
small team
rapid prototypes
programming
kanban
kiss
fun

6. :architecture

7. :architecture?
thin-client
object-oriented
relational database
symmetric/crud
evil ORM

8. :architecture!
rich client
functional
document database
command query responsibility segregation
event sourcing
REST api

9. :spike

10. :spike
java
scala
clojure

11. :spike
java
scala
clojure
and the winner is ...

12. :scala

13. :scala
I compile!

14. :scala
I compile!
no?

15. :clojure

16. :clojure
I compile too!

17. :clojure
Winner!

18. :clojure
core
noir
monger
midje
lein
...

19. :reasoning

20. :reasoning
functional & immutability

21. :reasoning
maps and vectors as first-class citizens

22. :reasoning
productivity
[lein repl]

23. :reasoning
noir

24. :reasoning
not= version horror

25. :reasoning
superior tools for data manipulation

26. :reasoning
superior tools for data manipulation
[clojure.walk clojure.set]

27. :reasoning
runs on the JVM

28. :reasoning
#euroclojure

29. :cqrs

30. :cqrs
separate reads and writes

31. :cqrs
1) lean start with querys

32. :cqrs
1) lean start with querys
2) iterate over features

33. :cqrs
1) lean start with querys
2) iterate over features
... adding commands

34. :cqrs
1) lean start with querys
2) iterate over features
... adding commands
= functions

35. :cqrs
1) lean start with querys
2) iterate over features
... adding commands
= functions
= domain logic

36. :cqrs
1) lean start with querys
2) iterate over features
... adding commands
= functions
= domain logic
➝ Functional Domain Models

37. :data

38. :data
evolutionary domain model

39. :data
evolutionary domain model
document database for this domain

40. :data
evolutionary domain model
document database for this domain
how to manage model changes?

41. :data
evolutionary domain model
document database for this domain
how to manage model changes?
... enter

42. :event-sourcing

43. :event-sourcing
persistent log of events

44. :event-sourcing
persistent log of events
state is fold over events

45. :event-sourcing
persistent log of events
state is fold over events
separate read aggregates

46. :event-sourcing
persistent log of events
state is fold over events
separate read aggregates
eventually consistent

47. :event-sourcing
persistent log of events
state is fold over events
separate read aggregates
eventually consistent
notion of time

48. :event-sourcing
persistent log of events
state is fold over events
separate read aggregates
eventually consistent
notion of time
audit trail

49. :event-sourcing
persistent log of events
state is fold over events
separate read aggregates
eventually consistent
notion of time
audit trail
[postponed]

50. :rest

51. :rest
simple

52. :rest
simple
easy (with noir)

53. :rest
simple
easy (with noir)
(defjson "/api/documents" [] (db/get-all :documents))
(defjson "/api/documents/:id" {id :id} (db/by-id :documents id))

54. :rest
simple
easy (with noir)
... but just a idiomatic proxy layer
(defjson "/api/documents" [] (db/get-all :documents))
(defjson "/api/documents/:id" {id :id} (db/by-id :documents id))

55. :rest
simple
easy (with noir)
... but just a idiomatic proxy layer
don’t need it in cqrs
(defjson "/api/documents" [] (db/get-all :documents))
(defjson "/api/documents/:id" {id :id} (db/by-id :documents id))

56. :api

57. :api
for sending commands and queries

58. :api
for sending commands and queries
(defjson [:post "/api/command/:name"] {name :name}
(execute (command name :data (from-json))))
(defjson [:get "/api/query/:name"] {name :name}
(execute (query name :data (from-request))))

59. :api
for sending commands and queries
...where’s the beef?
(defjson [:post "/api/command/:name"] {name :name}
(execute (command name :data (from-json))))
(defjson [:get "/api/query/:name"] {name :name}
(execute (query name :data (from-request))))

60. :core

61. :core
declarative validation via meta-data

62. :core
declarative validation via meta-data
registered functions for side-effects (via macros)

63. :core
declarative validation via meta-data
registered functions for side-effects (via macros)
(defcommand "close-application"
{:parameters [:id]
:roles [:applicant :authority]
:states [:open]}
[command]
(with-application command
(fn [{id :id}]
(db/update-by-id :applications id
{$set {:state :closed}}))))

64. :event bus

65. :event bus
some cool ideas about temporal state management

66. :event bus
some cool ideas about temporal state management
existing tools for both Scala & Clojure

67. :event bus
some cool ideas about temporal state management
existing tools for both Scala & Clojure
websockets

68. :layers

69. :layers
avoid

70. :layers
avoid
or pass-through

71. :layers
avoid
or pass-through
from database (view) to html

72. :layers
avoid
or pass-through
from database (view) to html
from html to commands

73. :cool-stuff

74. :cool-stuff
macros

75. :cool-stuff
macros
multi-methods

76. :cool-stuff
macros
multi-methods
live coding

77. :maybe

78. :maybe
clj-webdriver

79. :maybe
clj-webdriver
clojurescript

80. :maybe
clj-webdriver
clojurescript
LET’S HACKTODAY!

81. :maybe
clj-webdriver
clojurescript
LET’S HACKTODAY!
➝ post polyglot programming?

82. :developers

83. :developers
(def n 5)

84. 0"
5"
10"
15"
20"
25"
30"
1" 2" 3" 4" 5"
free"
work"
time with clojure

85. 0"
50"
100"
150"
200"
250"
300"
1" 2" 3" 4" 5"
now"
6kk"
efficiency

86. scala%
clojure%
java%
before project

87. scala%
clojure%
java%
current status

88. 0"
0.5"
1"
1.5"
2"
2.5"
3"
3.5"
0" 1" 2" 3" 4" 5"
java$love$
java"love"
next project

89. 0"
0.5"
1"
1.5"
2"
2.5"
3"
3.5"
0" 1" 2" 3" 4" 5"
clojure(love(
clojure"love"
next project

90. :summary
clojure is awesome
dead simple for restful web apps
cqrs for evolutionary domain models
optional event sourcing for time management
evolving from pattern to tools
➝ this is the way apps should be built

91. :summary
clojure is awesome
dead simple for restful web apps
cqrs for evolutionary domain models
optional event sourcing for time management
evolving from pattern to tools
➝ this is the way apps should be built

92. :demo

93. :demo
mac-based authentication