Software Design ... a nice expression, uh? But what does it mean to "design a software"? What are the prerequisites? What are the pitfalls to avoid? As Software Designers we would like to highlight on what makes us build simple, useful and above all effective software. And of course, we will talk about Domain-Driven Design in that journey ;-) Talk made at http://domain-driven-design.eu/the-art-of-design/

1. THE ART OF (SOFTWARE) DESIGN
Jérémie GRODZISKI - Thomas PIERRAIN
DDD Meetup - February 2017

2. HAS 'AGILE' KILLED
DESIGN IN SOFTWARE?

3. PROBABLY BUT…

4. ’AGILE' WANTED TO KILL
BIG UPFRONT DESIGN ONLY

5. BIG UPFRONT DESIGN
DESIGN
≠

6. LACK OF DESIGN
EMERGENT DESIGN
≠

7. DON'T THROW
THE BABY WITH
THE BATHWATER
DON’T THROW THE DESIGN « BABY » WITH…

8. WHAT IS DESIGN
?

9. DESIGN IS MAKING
DECISIONS

10. MAKING
DECISIONS TO
BUILD
SOMETHING

11. EVERYONE
IS MAKING
DECISIONS

12. EVERYONE IS MAKING
DECISIONS…
BUT WITH DIFFERENT
IMPACTS

13. BUILDING
SOMETHING
OK, BUT WHY?

14. WHY?
WHY?
WHY?
WHY?
WHY?
BUILDING
SOMETHING
OK, BUT WHY?

15. SOLUTION SPACE
PROBLEM SPACE
WHY
WHAT

16. HOW
SOLUTION SPACE

17. PROBLEM
SPACE
Problem
Usages
Languages
Domain
Requirements
Constraints
People

18. PROBLEM
SPACE
Problem
Usages
Languages
Domain
Requirements
Constraints
People
DOMAIN
( noun, do·main)
Set of concepts
That through
usages
Help to solve
problems

19. PROBLEM
SPACE
Problem
Usages
Languages
Domain
Requirements
Constraints
People
DOMAIN
Solve
Problems

20. SOLUTION SPACE
Software
Model
Design
Patterns
Heuristics
Feedback

21. Driven
PROBLEM
SPACE
Problem
Usages
Languages
Domain
Requirements
Constraints
People
SOLUTION SPACE
Software
Model
Design
Patterns
Heuristics
Feedback

22. PROBLEM
SPACE
Domain
SOLUTION SPACE
Design- Driven

23. HEURISTICS?
practical method not guaranteed to be
optimal or perfect, but sufficient for the
immediate goals.

24. PATTERNS
FAVORITES
ALGORITHMS
…
FAVORITES SOLUTIONS
FAVORITES
APPROACHES
OUR MENTAL MODELS

25. HOUSTON?

26. TRAPPED
BY YOUR OWN
HEURISTICS?

27. SYSTEMATIC LAYERS
ORMFRAMEWORKS
ANEMIC
BEHAVIORS
…IOC

28. FROM HEURISTICS TO
SOLUTION-FIRST BIAS

30. MOST
DEVELOPERS
LIKES…
SOLUTIONS

31. OUR USERS ARE
TIRED OF C.R.U.D.
APPLICATIONS

32. C.R.U.D.
APPLICATIONS

33. THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

34. Create
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

35. Ctrl-C
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

36. Update
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

37. Ctrl-V
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

38. Create
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

39. Ctrl-V
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

40. Update
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

41. Ctrl-V
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

42. …
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

43. I’m doing all
the job
actually…
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

44. THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

45. Damn it!
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

46. Damn I.T!
THE C.R.U.D.
BURDEN
CRUD app #1
CRUD app #2
CRUD app #3

47. WHY?!?

48. MANY REASONS BUT…

49. DATA MODELS
INSTEAD OF
DOMAIN MODELS

50. LAZINESS
« Laziness is nothing more
than the habit of resting
before you get tired. »
(Jules Renard)

51. A DDD
ALTERNATIVE?
THE APP REALLY HELPS
WITH A SPECIFIC & CONSISTANT USER JOURNEY

52. OTHER BIASES?

53. BEWARE OF
FADS
micro-services, blockchains, …

54. THE
ABSTRACTION-
FIRST PITFALL

55. CONCRETE
THINGS
FIRST!

56. THE CV-DRIVEN
DEVELOPMENT
PANDEMIC

57. I.T. AS
SEEN BY
THE
BUSINESS

58. WE MUST
FOCUS MORE ON
THE BUSINESS
CONCERNS!

59. DESIGN IS
CONSCIOUS
CHOICES
(Banksy)

60. ALWAYS
CONNECT YOUR DECISIONS
TO YOUR
BUSINESS OBJECTIVES

61. DESIGN IS
THE ART OF
TRADE-OFF

62. design = f(requirements + constraints)trade-off

63. DESIGN
SOFTWARE?

64. ALIGNMENT &
EFFICIENCY
solution space
problem space

65. SOME
CONSTRAINTS
(the mythical man-month)

66. THERMODYNAMICS
OF SOFTWARE

67. HEXAGONAL
ARCHITECTURE
DOMAIN
CODE
(domain first)

68. HEXAGONAL
ARCHITECTURE
DOMAIN
CODE
DO NOT MESS
BUSINESS CODE
INFRA CODE
(infra later)

69. STANDARD
SOFTWARE DESIGN
(take all your favorite
heuristics with you ;-(

70. CONSCIOUS
(SOFTWARE) DESIGN
(take only what you need for
the usages/contraints)

71. CONSCIOUS
(SOFTWARE) DESIGN
USAGES FIRST - INFRA LATER
HEXAGONAL ARCHITECTURE
EXAMPLES & BEHAVIOURS (TESTS) DRIVEN
EXPLICIT (AND BOUNDED) CONTEXTS

72. SOFTWARE DESIGN
VS.
REAL WORLD DESIGN?

73. DUPLICATION
OF
CODE AND DATA
AT ALMOST NO
COST

74. SCALING

75. EASY
MODULARIZATION
AND INTERFACING

76. BEWARE OF THE
BUILDING
METAPHOR

77. WRAP UP

78. MINDSET
APPROACH

79. MINDSET
APPROACH

80. ALWAYS MAKE
CONSCIOUS
DECISIONS
{ Value | Constraint }
(Banksy)

81. FOSTER
CONSCIOUS
DESIGN!

82. STAY CONSCIOUS
OF YOUR
BIAS

83. MINDSET
APPROACH

84. MINDSET
APPROACH

85. USAGES FIRST
…INFRA LATER

86. BE ADAPTABLE
RATHER THAN
PREDICTABLE

87. THANK YOU!
JOIN US @DDDREBOOT