ESUG 2012, Ghent

1. ESUG 2012
Extending a Base Product
for Multiple Customers
Denis Defreyne
MediaGeniX NG
1

2. 2

3. “
Your product is cool,
but it’s missing feature X!
— CUSTOMER
3

4. “
Yes, feature X would be nice…
for you, but nobody else!
— YOU
4

5. “
Why did you not
implement feature X? :(
— CUSTOMER
5

6. “
Ugh, this product is
getting bloated! :(
— OTHER CUSTOMER
6

7. Contents
1. Customisations
2. Techniques
3. Modules
7

8. 1. Customisations
8

9. Customisation =
extra bits of code
for a single customer
9

10. Customisations
‣ New functionality
e.g. new issue checks (no porn at noon)
‣ Extended functionality
e.g. extra metadata on films, contracts, …
‣ Changed functionality
e.g. parental rating management in UK, Finland
10

11. Integrations
‣ Playout server
‣ Commercial scheduling system
‣ Music scheduling system
‣ …
unique for every customer!
11

12. Customisations are
only possible if you
have FEW customers
12

13. Requirements
‣ Be customer-specific
‣ Be fine-grained
‣ Allow merging bugfixes
‣ Be decoupled
13

14. Why?
‣ Talk to other devices
You’ll have static on your TV otherwise
‣ Cater to a diverse market
No two broadcasters have the same workflow
‣ Resolve conflicting requirements
Don’t compromise, let them both have it their way
‣ Make customers happy!
But don’t over-do it :)
14

15. 15

16. 2. Techniques
16

17. Techniques
1. Site classes
2. Behaviors
3. Convenience methods
17

18. Techniques
1. Site classes
2. Behaviors
3. Convenience methods
18

19. Site classes – example
19

20. Site classes – example
20

21. Site class =
subclass for one
specific customer
21

22. Site = customer
22

23. Site classes
Film
23

24. Site classes
Film
FilmMTV
24

25. Site classes
Film class >> siteClassForMTV
^FilmMTV
MTV
25

26. Site classes
newAustinPowersFilm
^Film siteClass new
title: 'Adventures at ESUG';
duration: (Duration fromMinutes: 93);
yourself
BASE
26

27. Packages
MTV WHATS’On code for MTV only
BASE WHATS’On code shared between customers
FRAMEWORK MediaGeniX framework code
27

28. Packages
NRK TV2 PRO7
VRT MTV VPRO
VTM SBS FI NPO
FOX FTO …
28

29. Extensions in packages
PACKAGE A PACKAGE B
MusicClip Contract
MusicClip>>title Agreement
MusicClip>>videoFile
MusicClip>>audioFile MusicClip>>contract
MusicClip>>is16Plus MusicClip>>agency
29

30. Site classes
Film class >> siteClassForMTV
^FilmMTV
MTV
30

31. Site classes
BASE MTV
Film FilmMTV
MusicClip
Commercial Film>>siteClassForMTV
31

32. Film >> siteClassForMTV
Film siteClass new
32

33. Site classes
Class >> siteClass
^Site current siteClassOf: self
FRAMEWORK
33

34. Site classes
SiteMTV >> siteClassOf: aClass
^aClass siteClassForMTV
MTV
34

35. Site classes
Site >> siteClassOf: aClass
^aClass
BASE
35

36. Site classes – example
Film class >> buildSuperModelWith: aBuilder
super buildSuperModelWith: aBuilder.
aBuilder
addString: #title name: 'Title';
addDuration: #duration name: 'Duration'
BASE
36

37. 37

38. Site classes – example
Film class >> buildSuperModelWith: aBuilder
super buildSuperModelWith: aBuilder.
aBuilder
addString: #title name: 'Title';
addDuration: #duration name: 'Duration'
BASE
38

39. Site classes – example
FilmMTV class >> buildSuperModelWith: aBuilder
super buildSuperModelWith: aBuilder.
aBuilder
addString: #idForMTV name: 'ID for MTV'
MTV
39

40. Site classes – example
40

41. Site classes – example
41

42. Site classes – example
FilmEditor class >> form
^self newForm
addFormField: #title;
addFormField: #duration;
yourself
BASE
42

43. Site classes – example
FilmEditor >> siteClassForMTV
^FilmEditorMTV
FilmEditorMTV class >> form
^super form
addFormField: #idForMTV;
yourself
MTV
43

44. Site classes – example
44

45. Site classes – example
45

46. Site classes – example
FilmEditor class >> form
^self newForm
addFormField: #title;
addFormField: #duration;
addFormField: #imdbRating;
yourself
BASE
46

47. Site classes – example
47

48. Site classes – example
48

49. Site classes – example
Film >> openInEditor
^FilmEditor siteClass
openWithEditee: self
BASE
49

50. Call #siteClass everywhere?
YES!
It’s not as bad as you may think…
50

51. PRO TIP
Avoid long methods
51

52. Techniques
1. Site classes
2. Behaviors
3. Convenience methods
52

53. Behaviors
Product
Film Commercial MusicClip
53

54. Behaviors
Product
ProductMTV
54

55. Behaviors
Product
Film Commercial MusicClip
55

56. Behaviors
Product ProductBehavior
Film Commercial MusicClip ProductBehaviorMTV
56

57. Behavior class =
siteclassable class with
behavior from original class
57

58. Behaviors
BehaviorObject class >> newOn: anObject
^self new
orig: anObject;
yourself
FRAMEWORK
58

59. Behaviors – example
Product >> hasValidCertForTx: aTx
^self certification isOkayForTx: aTx
BASE
59

60. Behaviors – example
ProductBehavior >> hasValidCertForTx: aTx
^self orig certification isOkayForTx: aTx
BASE
60

61. Behaviors – example
ProductBehaviorMTV >> hasValidCertForTx: aTx
^self orig videoFiles allSatisfy:
[:f | f certification isOkayForTx: aTx]
MTV
61

62. Behaviors – example
Product >> hasValidCertForTx: aTx
^self behavior hasValidCertForTx: aTx
BASE
62

63. Behaviors – example
Product >> behavior
behavior ifNil:
[behavior := ProductBehavior siteClass
newOn: self].
^behavior
BASE
63

64. PRO TIP
Prefer composition
over inheritance
64

65. Techniques
1. Site classes
2. Behaviors
3. Convenience methods
65

66. Convenience method =
commonly implemented
or overridden method
66

67. Convenience methods
buildSuperModelWith: aBuilder
addToolsMenuItemsTo: aMenu
addCommandsToToolBar: aToolBar
67

68. Convenience methods
buildSuperModelWith: aBuilder
buildSuperModelForMTVWith: aBuilder
addToolsMenuItemsTo: aMenu
addToolsMenuItemsForMTVTo: aMenu
addCommandsToToolBar: aToolBar
addCommandsToToolBarForMTV: aToolBar
68

69. Convenience methods
FilmMTV class >> buildSuperModelWith: aBuilder
super buildSuperModelWith: aBuilder.
aBuilder
addString: #idForMTV name: 'ID for MTV'
MTV
69

70. Convenience methods
Film class >> buildSuperModelForMTVWith: aBuilder
super buildSuperModelForMTVWith: aBuilder.
aBuilder
addString: #idForMTV name: 'ID for MTV'
MTV
70

71. Convenience methods
Site >> buildSuperModelWith: aBuilder
for: aClass
aClass buildSuperModelWith: aBuilder
FRAMEWORK
71

72. Convenience methods
SiteMTV >> buildSuperModelWith: aBuilder
for: aClass
super buildSuperModelWith: aBuilder for: aClass.
aClass buildSuperModelForMTVWith: aBuilder.
MTV
72

73. PRO TIP
Use convenience methods
for common methods only
73

74. Techniques to avoid
‣ Branches
Use them, but not for customer-specific code
‣ VisualWorks “overrides”
They prevent access to original code
74

75. Techniques
1. Site classes
2. Behaviors
3. Convenience methods
75

76. 3. Modules
76

77. Module =
pluggable component
that provides a set of
related functionalities
77

78. Example modules
‣ Contract management
‣ Secondary events (logos)
‣ Video on demand
78

79. Super models in modules
Film class >> buildSuperModelWith: aBuilder
super
buildSuperModelWith: aBuilder.
WRONG
aBuilder
" … other attributes here … "
addReference: #contract
to: Contract name: 'Contract'
BASE
79

80. Activating modules
SiteMTV >> moduleClasses
^OrderedCollection new
add: ContractModule;
add: SecondaryEventsModule;
yourself
MTV
80

81. Super models in modules
81

82. Super models in modules
Film class >>
buildSuperModelForContractModuleWith: aBuilder
super
buildSuperModelForContractModuleWith: aBuilder.
aBuilder
addReference: #contract
to: Contract name: 'Contract'
BASE
82

83. Super models in modules
Site >> buildSuperModelWith: aBuilder
for: aClass
aClass buildSuperModelWith: aBuilder.
FRAMEWORK
83

84. Super models in modules
Site >> buildSuperModelWith: aBuilder
for: aClass
aClass buildSuperModelWith: aBuilder.
self modules do:
[:m |
m buildSuperModelWith: aBuilder for: aClass].
FRAMEWORK
84

85. Super models in modules
Module >> buildSuperModelWith: aBuilder
for: aClass
"nothing by default"
FRAMEWORK
85

86. Super models in modules
ContractPresentModule >> buildSuperModelWith: aBuilder
for: aClass
aClass buildSuperModelForContractModuleWith:
aBuilder.
BASE
86

87. Extensions in modules
87

88. Extensions in modules
FilmEditor class >> form
form := self newForm.
form addFormField: #title.
form addFormField: #duration.
^form
BASE
88

89. Extensions in modules
FilmEditor class >> form
form := self newForm.
WRONG
form addFormField: #title.
form addFormField: #duration.
form addFormField: #contract.
^form
BASE
89

90. Extensions in modules
FilmEditor class >> form
form := self newForm.
form addFormField: #title.
form addFormField: #duration.
ContractModule current
addFieldsTo: form for: self.
^form
BASE
90

91. Extensions in modules
ContractPresentModule >>
addFieldsTo: aForm
for: anEditor
anEditor addContractFieldsTo: aForm
BASE
91

92. Extensions in modules
FilmEditor >>
addContractFieldsTo: aForm
aForm addFormField: #contract.
BASE
92

93. Extensions in modules
ContractAbsentModule >>
addFieldsTo: aForm
for: aSender
"nothing by default"
BASE
93

94. Extensions in modules
CONTRACT
94

95. Extensions in modules
CONTRACT
95

96. Site classes vs. modules
‣ Modules can be shared across sites
‣ Modules require hooks
96

97. Recap
97

98. Techniques
‣ Use site classes
whenever possible
‣ Use behaviors
when site classes fail (inheritance trees)
‣ Use modules
when you need more separation
98

99. Requirements
‣ Be customer-specific (with packages)
‣ Be fine-grained (with site classes)
‣ Allow merging bugfixes (with packages)
‣ Be decoupled (with site classes and modules)
99

100. “
Your product is cool,
but it’s missing feature X!
— CUSTOMER
Do not worry.
We’ll implement it for you!
— YOU
100

101. ? MAIL denis.defreyne@mediagenix.tv
TWITTER @ddfreyne
GITHUB github.com/ddfreyne
101

102. Extra Slides
102

103. Site classing modules
Site >> modules
^self moduleClasses collect:
[:c | c siteClass new]
FRAMEWORK
103

104. Site classing modules
SuperModellary >> buildSuperModelFor: aClass
builder := SuperModelBuilder new.
Site current buildSuperModelWith: builder
for: aClass.
supermodels at: aClass put: builder superModel.
FRAMEWORK
104

105. Extensions in modules
FilmEditor class >> form
form := self newForm.
form addFormField: #title.
form addFormField: #duration.
ContractModule current
addFieldsTo: form for: self.
^form
BASE
105

106. Extensions in modules
FilmEditor class >> form
form := self newForm.
form addFormField: #title.
form addFormField: #duration.
ContractModule current isAvailable ifTrue:
[form addFormField: #contract].
^form
BASE
106

107. Extensions in modules
Film >> isLegallyBroadcastable
^ContractModule current isAvailable
ifFalse: [true]
ifTrue: [self contract isSigned].
BASE
107

108. Extensions in modules
Film >> isLegallyBroadcastable
^ContractModule current isAvailable
ifFalse: [true]
ifTrue: [self contract isSigned].
BASE
108

109. Extensions in modules
Film >> isLegallyBroadcastable
^ContractModule current
isFilmLegallyBroadcastable: self
BASE
109

110. Extensions in modules
ContractPresentModule >>
isFilmLegallyBroadcastable: aFilm
^aFilm contract isSigned
BASE
110

111. Extensions in modules
ContractAbsentModule >>
isFilmLegallyBroadcastable: aFilm
^true
BASE
111