Reactive System. What and How?

Transcript

1. Reactive System.
   What and How?
   by Oleh Dokuka
   

   View Slide

2. About me
   2
   

   View Slide

3. • JSE at Levi9
   About me
   2
   

   View Slide

4. • JSE at Levi9
   • JEEConf Speaker
   About me
   2
   

   View Slide

5. • JSE at Levi9
   • JEEConf Speaker
   • Spring fan
   About me
   2
   

   View Slide

6. • JSE at Levi9
   • JEEConf Speaker
   • Spring fan
   • Reactivity preacher
   About me
   2
   

   View Slide

7. • JSE at Levi9
   • JEEConf Speaker
   • Spring fan
   • Reactivity preacher
   /oleh.dokuka /OlegDokuka
   /OlehDokuka
   About me
   2
   

   View Slide

8. 3
   Agenda
   

   View Slide

9. 3
   • Reactive Approach
   Agenda
   

   View Slide

10. 3
    • Reactive System
    • Reactive Approach
    Agenda
    

    View Slide

11. 3
    • Reactive System
    • Reactive Programming
    • Reactive Approach
    Agenda
    

    View Slide

12. 3
    • Reactive System
    • Reactive Programming
    • Reactive Approach
    Agenda
    • Reactive In Action
    

    View Slide

13. Why Reactive?
    4
    

    View Slide

14. View Slide

15. View Slide

16. View Slide

17. Responsive?
    8
    

    View Slide

18. 9
    Responsive
    

    View Slide

19. 9
    Responsive
    

    View Slide

20. 10
    Responsive
    10
    

    View Slide

21. 10
    Responsive
    Elastic
    10
    

    View Slide

22. 10
    Responsive
    Elastic
    10
    

    View Slide

23. Responsive
    Elastic
    

    View Slide

24. Responsive
    Elastic Resilient
    

    View Slide

25. Responsive
    Elastic Resilient
    

    View Slide

26. 12
    Responsive
    Elastic Resilient
    12
    

    View Slide

27. 12
    Responsive
    Elastic Resilient
    12
    

    View Slide

28. 13
    Responsive
    Elastic Resilient
    

    View Slide

29. 13
    Responsive
    Elastic Resilient
    Message Driven
    

    View Slide

30. 13
    Responsive
    Elastic Resilient
    Message Driven
    

    View Slide

31. 13
    Responsive
    Elastic Resilient
    Message Driven
    

    View Slide

32. 13
    Responsive
    Elastic Resilient
    Message Driven
    

    View Slide

33. 14
    Responsive
    Elastic Resilient
    Message Driven
    

    View Slide

34. Reactive Manifesto
    15
    http://www.reactivemanifesto.org/
    

    View Slide

35. Common Vocabulary
    16
    

    View Slide

36. Reactive System
    17
    

    View Slide

37. Architecture
    18
    

    View Slide

38. 19
    Message Driven
    

    View Slide

39. Reactive Programming
    20
    

    View Slide

40. Reactive Programming
    !=
    Reactive System
    21
    

    View Slide

41. Reactive Programming
    Evolution
    22
    

    View Slide

42. Observer Pattern
    Event Listening
    23
    

    View Slide

43. View Slide

44. View Slide

45. View Slide

46. View Slide

47. View Slide

48. View Slide

49. new EventHandler() {
    void onEvent(Event event) {
    //do stuff
    }
    }
    27
    

    View Slide

50. eventSource.setHandler(
    new EventHandler() {
    void onEvent(Event event) {
    //do stuff
    }
    }
    );
    28
    

    View Slide

51. anotherEventSource.setHandler(
    new EventHandler() {
    void onEvent(Event event) {
    eventSource.setHandler(
    new EventHandler() {
    void onEvent(Event event) {
    //do stuff
    }
    }
    );
    }
    }
    ); 29
    

    View Slide

52. Pyramid of Doom
    30
    

    View Slide

53. Async operation?
    31
    

    View Slide

54. Framework’s Way
    32
    

    View Slide

55. @Component EventHandler() {
    @EventListener
    void onEvent(Event event) {
    //do stuff
    }
    }
    33
    

    View Slide

56. @Component EventHandler() {
    @EventListener
    void onEvent(Event event) {
    //do stuff
    }
    }
    34
    

    View Slide

57. No Clear Flow
    35
    

    View Slide

58. Reactive Extension
    36
    

    View Slide

59. Rx.Net
    37
    

    View Slide

60. 38
    DataSource Subscriber
    

    View Slide

61. 38
    DataSource
    Observable
    Subscriber
    

    View Slide

62. 39
    Observable
    DataSource Subscriber
    

    View Slide

63. 39
    Observable
    DataSource
    Observer
    Subscriber
    

    View Slide

64. 40
    Observable
    DataSource Subscriber
    Observer
    

    View Slide

65. 40
    Observable
    DataSource Subscriber
    onNext()
    onError()
    onComplete()
    Observer
    

    View Slide

66. 40
    Observable
    DataSource Subscriber
    onNext()
    onError()
    onComplete()
    Observer
    

    View Slide

67. 41
    onNext()
    onError()
    onComplete()
    Observable Observer
    Subscriber
    DataSource
    

    View Slide

68. 41
    onNext()
    onError()
    onComplete()
    Observable Observer
    Subscriber
    DataSource
    Observer
    Transform
    onNext()
    onError()
    onComplete()
    

    View Slide

69. 41
    onNext()
    onError()
    onComplete()
    Observable Observer
    Subscriber
    DataSource
    Observer
    Transform
    onNext()
    onError()
    onComplete()
    

    View Slide

70. Observer
    Transform
    42
    Observable Observer
    Subscriber
    DataSource
    onNext()
    onError()
    onComplete()
    onNext()
    onError()
    onComplete()
    

    View Slide

71. IObservable
    43
    

    View Slide

72. IObserver
    44
    

    View Slide

73. public interface IObserver
    {
    // Notifies the observer that
    // the source has finished sending messages.
    void OnCompleted();
    // Notifies the observer about any
    // exception or error.
    void OnError(Exception error);
    // Pushes the next data value from
    // the source to the observer.
    void OnNext(T value);
    }
    45
    

    View Slide

74. public interface IObserver
    {
    // Notifies the observer that
    // the source has finished sending messages.
    void OnCompleted();
    // Notifies the observer about any
    // exception or error.
    void OnError(Exception error);
    // Pushes the next data value from
    // the source to the observer.
    void OnNext(T value);
    }
    46
    

    View Slide

75. public interface IObserver
    {
    // Notifies the observer that
    // the source has finished sending messages.
    void OnCompleted();
    // Notifies the observer about any
    // exception or error.
    void OnError(Exception error);
    // Pushes the next data value from
    // the source to the observer.
    void OnNext(T value);
    }
    47
    

    View Slide

76. public interface IObserver
    {
    // Notifies the observer that
    // the source has finished sending messages.
    void OnCompleted();
    // Notifies the observer about any
    // exception or error.
    void OnError(Exception error);
    // Pushes the next data value from
    // the source to the observer.
    void OnNext(T value);
    }
    48
    

    View Slide

77. API
    Transformations, Operations, etc.
    49
    

    View Slide

78. API
    .just()
    .from()
    .defer()
    .map()
    .filter()
    .flatMap()
    etc.
    50
    

    View Slide

79. Benefit
    51
    

    View Slide

80. observable.businessFunction()
    .map(mapFunction())
    .filter(filterFunction())
    .map(mapFunction())
    .doOnNext(someAction())
    .subscribe()
    52
    

    View Slide

81. Clear flow!
    Looks imperative, but actually async non-blocking
    processing of events
    53
    

    View Slide

82. Order Processing Flow
    54
    

    View Slide

83. RxJava
    Successful Story of Copy/Paste
    55
    

    View Slide

84. Observable
    56
    

    View Slide

85. class Observable {
    ...
    static Observable from(T... items)
    static Observable range(...)
    static Observable just(T value)
    ...
    }
    57
    

    View Slide

86. class Observable {
    ...
    Observable map(...)
    Observable filter(...)
    Observable flatMap(...)
    ...
    }
    58
    

    View Slide

87. Observer
    59
    

    View Slide

88. interface Observer {
    void onCompleted();
    void onError(Throwable e);
    void onNext(T args);
    }
    60
    

    View Slide

89. Subscription
    61
    

    View Slide

90. class Observable {
    ...
    Subscription subscribe(Observer observer){
    ...
    }
    ...
    }
    62
    

    View Slide

91. class Observable {
    ...
    Subscription subscribe(Observer observer){
    ...
    }
    ...
    }
    63
    

    View Slide

92. class Observable {
    ...
    Subscription subscribe(Observer observer){
    ...
    }
    ...
    }
    64
    

    View Slide

93. class Observable {
    ...
    Subscription subscribe(Observer observer){
    ...
    }
    ...
    }
    65
    

    View Slide

94. Flow Examples
    66
    

    View Slide

95. Source Creation
    67
    

    View Slide

96. Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    68
    

    View Slide

97. Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    .just( )
    a
    Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    68
    

    View Slide

98. .just( )
    a
    a
    Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    69
    

    View Slide

99. .just( )
    a
    a
    onNext()
    onError()
    onComplete()
    Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    Observable
    .just("a")
    .subscribe(
    onNext(),
    onError(),
    onComplete()
    )
    69
    

    View Slide

100. .just( )
     onNext()
     onError()
     onComplete()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     a
     70
     

     View Slide

101. .just( )
     .just( )
     onNext()
     onNext()
     onError()
     onComplete()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     a
     70
     

     View Slide

102. onNext()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     a
     onError()
     onComplete()
     71
     

     View Slide

103. onNext()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     onNext()
     .just( )
     onError()
     onComplete()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     onComplete()
     71
     

     View Slide

104. onComplete()
     onNext()
     .just( )
     onError()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     72
     

     View Slide

105. onComplete()
     onNext()
     .just( )
     onError()
     onComplete()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     72
     

     View Slide

106. Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     onNext()
     Observable
     .just("a")
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     onError()
     onComplete()
     onComplete()
     onComplete()
     73
     

     View Slide

107. Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     74
     

     View Slide

108. Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from(asList( ))
     a b
     74
     

     View Slide

109. 75
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from(asList( ))
     a b
     

     View Slide

110. 75
     onNext()
     onError()
     onComplete()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from(asList( ))
     a b
     

     View Slide

111. .from(asList( ))
     76
     onNext()
     onError()
     onComplete()
     a
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     b
     

     View Slide

112. .from(asList( ))
     .from(asList( ))
     76
     onNext()
     onError()
     onComplete()
     onNext()
     a
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     b
     

     View Slide

113. onNext()
     onComplete()
     .from(asList( ))
     onError()
     .from(asList( ))
     77
     onError()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     a b
     

     View Slide

114. onComplete()
     onNext()
     onComplete()
     onNext()
     .from(asList( ))
     onError()
     .from(asList( ))
     77
     onError()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

115. onNext()
     onComplete()
     onNext()
     .from(asList( ))
     onComplete()
     onError()
     .from(asList( ))
     78
     onError()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

116. onNext()
     onComplete()
     onNext()
     .from(asList( ))
     onComplete()
     onError()
     .from(asList( ))
     78
     onError()
     onComplete()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

117. .from(asList( ))
     onComplete()
     onError()
     79
     onNext()
     Observable
     .from(asList("a","b"))
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

118. 80
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

119. 80
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .defer()
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

120. Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     81
     .defer()
     

     View Slide

121. Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     81
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .defer()
     onNext()
     onError()
     onComplete()
     

     View Slide

122. Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     onNext()
     onError()
     onComplete()
     82
     .defer()
     

     View Slide

123. Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     onNext()
     onError()
     onComplete()
     82
     .just( )
     a b
     .defer()
     .defer()
     

     View Slide

124. .just( )
     onNext()
     onError()
     onComplete()
     83
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     a b
     .defer()
     

     View Slide

125. .just( )
     onNext()
     onNext()
     onError()
     onComplete()
     83
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     a b
     .defer()
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

126. onNext()
     onError()
     onComplete()
     84
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     .defer()
     a b
     

     View Slide

127. onNext()
     onNext()
     onError()
     onComplete()
     onComplete()
     84
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     .defer()
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

128. onComplete()
     onNext()
     onError()
     85
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     .defer()
     

     View Slide

129. onComplete()
     onNext()
     onError()
     onComplete()
     85
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     .defer()
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

130. onNext()
     onError()
     onComplete()
     onComplete()
     onComplete()
     86
     Observable
     .defer(() ->
     just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     .defer()
     

     View Slide

131. Transformations
     87
     

     View Slide

132. 88
     .map(…)
     .map()
     

     View Slide

133. 88
     .map(…)
     .map()
     

     View Slide

134. 89
     .filter(…)
     .filter()
     

     View Slide

135. 89
     .filter(…)
     .filter()
     

     View Slide

136. 90
     .flatMap(…)
     .flatMap()
     

     View Slide

137. 90
     .flatMap(…)
     .flatMap()
     

     View Slide

138. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     91
     

     View Slide

139. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     91
     .map()
     .filter()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     

     View Slide

140. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .filter()
     .map()
     92
     

     View Slide

141. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .filter()
     .map()
     92
     

     View Slide

142. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .map()
     .filter()
     93
     

     View Slide

143. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .map()
     .filter()
     93
     

     View Slide

144. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .map()
     94
     .filter()
     

     View Slide

145. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .map()
     94
     .filter()
     

     View Slide

146. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .subscribe()
     .map()
     .filter()
     95
     

     View Slide

147. Thread Manipulation
     96
     

     View Slide

148. Thread A
     Thread Main
     .observeOn(…)
     .observeOn()
     97
     

     View Slide

149. Thread A
     Thread Main
     .observeOn(…)
     .observeOn()
     97
     

     View Slide

150. 98
     .subscribeOn()
     Thread Main
     Thread A
     .subscribeOn(…)
     

     View Slide

151. 98
     .subscribeOn()
     Thread Main
     Thread A
     .subscribeOn(…)
     

     View Slide

152. 98
     .subscribeOn()
     Thread Main
     Thread A
     .subscribeOn(…)
     

     View Slide

153. Quiz
     99
     

     View Slide

154. Observable
     .just(1, 20, 300, 4000)
     .map(Object::toString)
     .filter(v -> v.length() > 3)
     100
     Output?
     

     View Slide

155. Observable
     .just(1, 20, 300, 4000)
     .map(Object::toString)
     .filter(v -> v.length() > 3)
     .subscribe(System.out::println)
     Output?
     101
     

     View Slide

156. Output?
     102
     Observable
     .just(1, 20, 300, 4000)
     .map(Object::toString)
     .filter(v -> v.length() > 3)
     .subscribe(System.out::println)
     

     View Slide

157. Hot vs. Cold
     Observables
     103
     

     View Slide

158. Cold
     104
     

     View Slide

159. .from( )
     4
     3
     2
     1
     Observable
     .just(1, 2, 3, 4)
     1 2 3 4
     105
     

     View Slide

160. .from( )
     4
     3
     2
     1
     Observable
     .just(1, 2, 3, 4)
     1
     2
     3
     4
     .subscribe()
     105
     

     View Slide

161. .from( )
     4
     3
     2
     1
     Observable
     .just(1, 2, 3, 4)
     1
     2
     3
     4
     1 2 3 4
     .subscribe()
     106
     

     View Slide

162. .from( )
     4
     3
     2
     1
     Observable
     .just(1, 2, 3, 4)
     1
     2
     3
     4 1
     2
     3
     4
     .subscribe()
     .subscribe()
     106
     

     View Slide

163. .from( )
     4
     3
     2
     1
     Observable
     .just(1, 2, 3, 4)
     1
     2
     3
     4 1
     2
     3
     4
     .subscribe()
     .subscribe()
     107
     

     View Slide

164. Hot
     108
     

     View Slide

165. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     109
     

     View Slide

166. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     109
     

     View Slide

167. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .filter()
     .map()
     110
     

     View Slide

168. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .filter()
     .map()
     110
     

     View Slide

169. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     111
     

     View Slide

170. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     111
     

     View Slide

171. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     112
     

     View Slide

172. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .filter()
     112
     

     View Slide

173. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     113
     

     View Slide

174. externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     114
     

     View Slide

175. .subscribe()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     114
     

     View Slide

176. .subscribe()
     externalService
     .messagesStream()
     .map(...)
     .filter(...)
     .map()
     .filter()
     115
     

     View Slide

177. RxJava Cons
     116
     

     View Slide

178. RxJava Cons
     116
     

     View Slide

179. RxJava Cons
     • Not easy to understand
     • Unexpected behaviors
     • Complicated extensibility
     • No backpressure
     117
     

     View Slide

180. View Slide

181. Problem
     119
     

     View Slide

182. Reactive Streams
     120
     

     View Slide

183. Purpose?
     121
     

     View Slide

184. Common API
     122
     

     View Slide

185. 123
     Publisher
     

     View Slide

186. 123
     Publisher
     Observable
     like
     

     View Slide

187. 124
     Subscriber
     

     View Slide

188. 124
     Subscriber
     Observer
     like
     

     View Slide

189. 125
     public interface Publisher {
     public void subscribe(
     Subscriber super T> s
     );
     }
     

     View Slide

190. 126
     .publish( )
     a Publisher
     

     View Slide

191. 126
     .publish( )
     a
     Subscriber
     .subscribe()
     Publisher
     Publisher
     

     View Slide

192. 127
     Subscription
     

     View Slide

193. 128
     public interface Subscriber {
     public void onSubscribe(Subscription s);
     public void onNext(T t);
     public void onError(Throwable t);
     public void onComplete();
     }
     

     View Slide

194. 128
     public interface Subscriber {
     public void onSubscribe(Subscription s);
     public void onNext(T t);
     public void onError(Throwable t);
     public void onComplete();
     }
     public interface Subscriber {
     public void onSubscribe(Subscription s);
     public void onNext(T t);
     public void onError(Throwable t);
     public void onComplete();
     }
     

     View Slide

195. public interface Subscription {
     public void request(long n);
     public void cancel();
     }
     129
     

     View Slide

196. public interface Subscription {
     public void request(long n);
     public void cancel();
     }
     129
     public interface Subscription {
     public void request(long n);
     public void cancel();
     }
     

     View Slide

197. Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     } 130
     .publish( )
     a
     .subscribe()
     Publisher
     

     View Slide

198. Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     }
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     } 130
     .publish( )
     a
     .subscribe()
     Publisher
     

     View Slide

199. Publisher
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     }
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     } 131
     .publish( )
     .subscribe()
     a
     

     View Slide

200. Publisher
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     }
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     } 131
     .publish( )
     .subscribe()
     Publisher
     a
     

     View Slide

201. Publisher
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     }
     Subscriber {
     void onSubscribe(Subscription s){
     s.request(1);
     }
     …
     } 131
     .publish( )
     .subscribe()
     Publisher
     a
     

     View Slide

202. Backpressure Support
     132
     

     View Slide

203. 133
     Processor
     

     View Slide

204. 134
     interface Processor
     extends
     Subscriber,
     Publisher {
     }
     

     View Slide

205. 135
     .publish( )
     .subscribe()
     Publisher
     a
     Subscriber
     

     View Slide

206. 135
     .publish( )
     .subscribe()
     Publisher
     a
     .process() Processor
     Subscriber
     Publisher
     Subscriber
     

     View Slide

207. Processor
     .publish( )
     136
     .subscribe()
     Publisher
     a
     .process()
     Subscriber
     

     View Slide

208. Processor
     Processor {
     s.request(1);
     }
     Processor {
     s.request(1);
     }
     .publish( )
     136
     .subscribe()
     Publisher
     a
     .process()
     Subscriber
     

     View Slide

209. Processor
     Processor {
     s.request(1);
     }
     .publish( )
     b
     .process()
     137
     .subscribe()
     Publisher
     a
     Subscriber
     

     View Slide

210. Processor
     Processor {
     s.request(1);
     }
     .publish( )
     b
     .process()
     137
     .subscribe()
     Publisher
     Subscriber
     a
     

     View Slide

211. Processor {
     s.request(1);
     }
     .publish( )
     b
     .process()
     138
     .subscribe()
     Publisher
     Subscriber
     a
     

     View Slide

212. Processor {
     s.request(1);
     }
     Processor {
     s.request(1);
     }
     Processor {
     s.request(1);
     }
     .publish( )
     b
     .process()
     138
     .subscribe()
     Publisher
     Subscriber
     a
     

     View Slide

213. Processor
     Processor {
     s.request(1);
     }
     .publish( )
     .process()
     139
     .subscribe()
     Publisher
     Subscriber
     a
     b
     

     View Slide

214. Processor
     Processor {
     s.request(1);
     }
     .publish( )
     .process()
     139
     .subscribe()
     Publisher
     Subscriber
     a
     b
     

     View Slide

215. Subscriber
     Processor
     140
     .publish( )
     .subscribe()
     Publisher
     .process() Processor
     b a
     

     View Slide

216. Subscriber
     Subscriber {
     s.request(2);
     }
     Processor
     140
     .publish( )
     .subscribe()
     Publisher
     .process() Processor
     b a
     

     View Slide

217. Subscriber
     Processor
     141
     .publish( )
     .subscribe()
     Publisher
     .process() Processor
     Subscriber
     b a
     

     View Slide

218. Subscriber
     Processor
     141
     .publish( )
     .subscribe()
     Publisher
     .process() Processor
     Subscriber
     b a Subscriber
     

     View Slide

219. Subscriber
     Subscriber
     Processor
     142
     .publish( )
     .subscribe()
     Publisher
     .process() Processor
     b a
     

     View Slide

220. Project Reactor
     143
     

     View Slide

221. by
     144
     

     View Slide

222. RxJava-like API
     145
     

     View Slide

223. Benefit
     146
     

     View Slide

224. Benefit
     146
     

     View Slide

225. Reactive Types
     147
     

     View Slide

226. Flux
     148
     

     View Slide

227. Flux
     148
     Observable
     like
     

     View Slide

228. 149
     abstract class Flux implements Publisher
     {
     ...
     static Flux from(...)
     static Flux range(...)
     static Flux just(T data)
     ...
     }
     

     View Slide

229. 150
     abstract class Flux implements Publisher
     {
     ...
     Flux map(...)
     Flux filter(...)
     Flux flatMap(...)
     ...
     }
     

     View Slide

230. Mono
     151
     

     View Slide

231. Mono
     151
     ?????????????
     like
     

     View Slide

232. View Slide

233. Mono
     153
     Observable
     like
     

     View Slide

234. BUT!
     154
     

     View Slide

235. For Zero or One
     element
     155
     

     View Slide

236. 156
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     

     View Slide

237. 157
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     

     View Slide

238. 157
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     onNext()
     onError()
     onComplete()
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

239. .from( ____
     )
     .just( )
     a b
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     158
     onNext()
     onError()
     onComplete()
     

     View Slide

240. .from( ____
     )
     .just( )
     a b
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     158
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     onNext()
     onError()
     onComplete()
     

     View Slide

241. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     159
     .from( ____
     )
     .just( )
     b
     onNext()
     onError()
     onComplete()
     a
     

     View Slide

242. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .just( )
     a b
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     159
     .from( ____
     )
     .just( )
     b
     onNext()
     onError()
     onComplete()
     onNext()
     a
     

     View Slide

243. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .from( ____
     )
     .just( )
     a b
     160
     .just( )
     onNext()
     onError()
     onComplete()
     a
     b
     

     View Slide

244. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .from( ____
     )
     .from( ____
     )
     .just( )
     a b
     160
     .just( )
     onNext()
     onError()
     onComplete()
     a
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     b
     

     View Slide

245. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .from( ____
     )
     .from( ____
     )
     .just( )
     a b
     160
     .just( )
     onNext()
     onError()
     onComplete()
     a
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .just( )
     

     View Slide

246. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .from( ____
     )
     .just( )
     a b
     161
     .just( )
     onNext()
     onError()
     onComplete()
     a
     .just( )
     

     View Slide

247. Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     .from( ____
     )
     .from( ____
     )
     .just( )
     a b
     161
     .just( )
     onNext()
     onError()
     onComplete()
     a
     .just( )
     onComplete()
     Mono.from(
     Flux.just("a", "b")
     )
     .subscribe(
     onNext(),
     onError(),
     onComplete()
     )
     

     View Slide

248. API
     Operations, Transformations, etc.
     162
     

     View Slide

249. API
     .merge() & .mergeWith()
     .zip() & .zipWith()
     .publish()
     etc.
     163
     

     View Slide

250. .merge()
     .merge(…)
     164
     

     View Slide

251. .merge()
     .merge(…)
     164
     

     View Slide

252. 165
     Flux.merge(
     Flux.just("a"),
     Flux.just("b")
     )
     .mergeWith(Flux.just("c"));
     

     View Slide

253. .zip()
     .zip(…)
     166
     

     View Slide

254. .zip()
     .zip(…)
     166
     

     View Slide

255. .zip()
     .zip(…)
     166
     

     View Slide

256. .zip(…)
     167
     .zip()
     

     View Slide

257. .zip(…)
     167
     .zip()
     

     View Slide

258. 168
     Flux.zip(
     Flux.just("a"),
     Flux.just("b"),
     (a, b) -> a + b
     )
     .zipWith(Flux.just("c"),
     (ab, c) -> ab + c);
     

     View Slide

259. 169
     .from()
     

     View Slide

260. 169
     .from()
     static Flux from(Publisher source)
     static Mono from(Publisher source)
     

     View Slide

261. 170
     Flux
     .from(externalPublisher())
     .from()
     

     View Slide

262. 171
     Mono
     .from(externalPublisher())
     .from()
     

     View Slide

263. 172
     .fromStream()
     

     View Slide

264. 172
     .fromStream()
     static Flux fromStream(Stream s)
     

     View Slide

265. 173
     Flux.fromStream(
     Stream.of("a", "b")
     )
     

     View Slide

266. Backpressure Support
     174
     .onBackpressureBuffer()
     .onBackpressureDrop()
     .onBackpressureLatest()
     etc.
     

     View Slide

267. Summary
     1st Part
     175
     

     View Slide

268. Reactivity in Action
     176
     

     View Slide

269. Action Plan
     Refactoring
     177
     

     View Slide

270. Chat Application
     178
     

     View Slide

271. Functionality
     • Gitter Chat Communication
     • Messaging Statistics
     179
     

     View Slide

272. https://goo.gl/XcnEnr
     180
     

     View Slide

273. Demo
     181
     

     View Slide

274. Toolkit
     • Spring Framework 4.x
     • Spring MVC
     • Spring Data JPA
     • Spring Boot 1.5.x
     182
     

     View Slide

275. Architecture
     183
     

     View Slide

276. View Slide

277. User Client
     184
     

     View Slide

278. Gitter Service
     184
     

     View Slide

279. Whole Application
     184
     

     View Slide

280. Controllers Layer
     184
     

     View Slide

281. Service Layer
     184
     

     View Slide

282. DB Layer
     184
     

     View Slide

283. Controllers
     185
     

     View Slide

284. Thymeleaf View
     186
     

     View Slide

285. REST Resources
     187
     

     View Slide

286. Services
     188
     

     View Slide

287. External Chats SPI
     189
     

     View Slide

288. Domain Services
     190
     

     View Slide

289. Gitter Integration
     191
     

     View Slide

290. Service
     Implementations
     192
     

     View Slide

291. Persistence
     193
     

     View Slide

292. Database Model
     194
     

     View Slide

293. Existing Flow
     195
     

     View Slide

294. View Slide

295. View Slide

296. View Slide

297. View Slide

298. View Slide

299. View Slide

300. View Slide

301. View Slide

302. Problems
     200
     

     View Slide

303. Problems
     • Pulling model
     201
     

     View Slide

304. View Slide

305. View Slide

306. Problems
     • Pulling model
     • Blocking I/O
     203
     

     View Slide

307. Solutions
     204
     

     View Slide

308. Reactive Manifesto
     205
     

     View Slide

309. View Slide

310. View Slide

311. View Slide

312. Async Messaging
     Push Model
     207
     

     View Slide

313. Gitter
     Streaming API
     208
     

     View Slide

314. View Slide

315. View Slide

316. View Slide

317. View Slide

318. View Slide

319. Async Messaging
     Elasticity
     211
     

     View Slide

320. Reactive DB Driver
     212
     

     View Slide

321. View Slide

322. View Slide

323. View Slide

324. View Slide

325. View Slide

326. Async Messaging
     Push Model
     215
     

     View Slide

327. WebSocket
     216
     

     View Slide

328. View Slide

329. View Slide

330. One Solution for
     Everything
     218
     

     View Slide

331. Spring 5 :)
     219
     

     View Slide

332. Painless Replacement
     220
     

     View Slide

333. Reactive Stack (WebFlux)
     @Controller, @RequestMapping,…
     Spring MVC
     Servlet API
     Servlet Container
     Spring Web Reactive
     Reactive HTTP
     Servlet, Netty, Undertow
     221
     

     View Slide

334. @RestController
     @RequestMapping("/api/v1/statistics")
     public class StatisticResource {
     private final StatisticService statisticService;
     @Autowired
     public StatisticResource(
     StatisticService statisticService) {
     this.statisticService = statisticService;
     }
     @GetMapping("/users")
     public List getUsersStatistic() {
     return statisticService.getUsersStatistic();
     }
     }
     222
     

     View Slide

335. @RestController
     @RequestMapping("/api/v1/statistics")
     public class StatisticResource {
     private final StatisticService statisticService;
     @Autowired
     public StatisticResource(
     StatisticService statisticService) {
     this.statisticService = statisticService;
     }
     @GetMapping("/users")
     public List getUsersStatistic() {
     return statisticService.getUsersStatistic();
     }
     }
     223
     

     View Slide

336. @RestController
     @RequestMapping("/api/v1/statistics")
     public class StatisticResource {
     private final StatisticService statisticService;
     @Autowired
     public StatisticResource(
     StatisticService statisticService) {
     this.statisticService = statisticService;
     }
     @GetMapping("/users")
     public Flux getUsersStatistic() {
     return Flux.fromIterable(statisticService
     .getUsersStatistic());
     }
     224
     

     View Slide

337. @RestController
     @RequestMapping("/api/v1/statistics")
     public class StatisticResource {
     private final StatisticService statisticService;
     @Autowired
     public StatisticResource(
     StatisticService statisticService) {
     this.statisticService = statisticService;
     }
     @GetMapping("/users")
     public Flux getUsersStatistic() {
     return Flux.fromIterable(statisticService
     .getUsersStatistic());
     }
     225
     

     View Slide

338. View Slide

339. View Slide

340. View Slide

341. Why Netty?
     228
     

     View Slide

342. Asynchronous
     event-driven framework
     229
     

     View Slide

343. New
     Reactive Architecture
     230
     

     View Slide

344. Data Base Connection Pipe
     Gitter Connection Pipe
     231
     Client Connection Pipe
     

     View Slide

345. Data Base Connection Pipe
     Gitter Connection Pipe
     231
     Client Connection Pipe
     

     View Slide

346. Refactoring Steps
     232
     

     View Slide

347. 1. Update to Spring 5
     2. Reactive Interfaces
     3. Reactive Services
     4. Reactive Endpoints
     233
     

     View Slide

348. https://goo.gl/yxAJGI
     234
     

     View Slide

349. Update To Spring 5
     235
     

     View Slide

350. Code Session
     236
     

     View Slide

351. Reactive Interfaces
     237
     

     View Slide

352. Reactive DB Access
     ReactiveCrudRepository
     238
     

     View Slide

353. interface ReactiveCrudRepository extends Repository
     Mono save(S entity);
     Flux saveAll(Iterable entities);
     Flux saveAll(Publisher entityStream);
     Mono findById(ID id);
     Mono findById(Mono id);
     Mono existsById(ID id);
     Mono existsById(Mono id);
     Flux findAll();
     Flux findAllById(Iterable ids);
     Flux findAllById(Publisher idStream);
     Mono count();
     Mono deleteById(ID id);
     Mono delete(T entity);
     Mono deleteAll(Iterable extends T> entities);
     Mono deleteAll(Publisher extends T> entityStream);
     Mono deleteAll();
     } 239
     

     View Slide

354. interface ReactiveCrudRepository extends Repository
     Mono save(S entity);
     Flux saveAll(Iterable entities);
     Flux saveAll(Publisher entityStream);
     Mono findById(ID id);
     Mono findById(Mono id);
     Mono existsById(ID id);
     Mono existsById(Mono id);
     Flux findAll();
     Flux findAllById(Iterable ids);
     Flux findAllById(Publisher idStream);
     Mono count();
     Mono deleteById(ID id);
     Mono delete(T entity);
     Mono deleteAll(Iterable extends T> entities);
     Mono deleteAll(Publisher extends T> entityStream);
     Mono deleteAll();
     } 240
     

     View Slide

355. Code Session
     241
     

     View Slide

356. Reactive Services
     242
     

     View Slide

357. Gitter Service
     243
     

     View Slide

358. Reactive WebClient
     Out-of-the-box
     244
     

     View Slide

359. public interface WebClient {
     UriSpec> get();
     //omitted...
     static WebClient create() {
     return new DefaultWebClientBuilder().build();
     }
     interface RequestHeadersSpec> {
     //omitted...
     Mono exchange();
     //omitted...
     }
     interface ResponseSpec {
     Mono bodyToMono(Class bodyType);
     Flux bodyToFlux(Class elementType);
     Mono> toEntity(Class bodyType);
     Mono>> toEntityList(Class element
     }
     } 245
     

     View Slide

360. public interface WebClient {
     UriSpec> get();
     //omitted...
     static WebClient create() {
     return new DefaultWebClientBuilder().build();
     }
     interface RequestHeadersSpec> {
     //omitted...
     Mono exchange();
     //omitted...
     }
     interface ResponseSpec {
     Mono bodyToMono(Class bodyType);
     Flux bodyToFlux(Class elementType);
     Mono> toEntity(Class bodyType);
     Mono>> toEntityList(Class element
     }
     } 246
     

     View Slide

361. View Slide

362. View Slide

363. Code Session
     248
     

     View Slide

364. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     249
     

     View Slide

365. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     249
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

366. 250
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

367. 250
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

368. .getMS()
     .getLM()
     .retry()
     cache
     251
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

369. .getMS()
     .getLM()
     .retry()
     cache
     251
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

370. .getLM() .getMS()
     .retry()
     cache
     252
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

371. .getLM() .getMS()
     .retry()
     cache
     252
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

372. .getMS()
     .getLM()
     .retry()
     cache
     253
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

373. .getMS()
     .getLM()
     .retry()
     cache
     253
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getLM()
     

     View Slide

374. .getMS()
     .getLM()
     .retry()
     cache
     254
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

375. .getMS()
     .getLM()
     .retry()
     cache
     254
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

376. .getMS()
     .getLM()
     .retry()
     cache
     255
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

377. .getMS()
     .getLM()
     .retry()
     cache
     255
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

378. .getMS()
     .getLM()
     .retry()
     cache
     256
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

379. .getMS()
     .getLM()
     .retry()
     cache
     256
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

380. .getMS()
     .getLM()
     .retry()
     cache
     257
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

381. .getMS()
     .getLM()
     .retry()
     cache
     257
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

382. 258
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

383. …subscribe();
     258
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

384. …subscribe();
     258
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     

     View Slide

385. …subscribe();
     259
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

386. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     260
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

387. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     260
     .getMS()
     .getLM()
     .retry()
     cache
     .getMS()
     .retry()
     

     View Slide

388. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     261
     .getMS()
     .getLM()
     .retry()
     cache
     

     View Slide

389. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     261
     .getMS()
     .getLM()
     .retry()
     cache
     …subscribe();
     

     View Slide

390. @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     261
     .getMS()
     .getLM()
     .retry()
     cache
     …subscribe();
     

     View Slide

391. …subscribe();
     262
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     .getMS()
     .getLM()
     .retry()
     cache
     @Autowired
     public GitterService(
     GitterClient gitterClient
     ) {
     gas = Flux.merge(
     getLatestMessages(),
     getMessagesStream(null)
     )
     .retryWhen(...)
     .replay(30)
     .autoConnect(0);
     }
     …subscribe();
     

     View Slide

392. Message Service
     263
     

     View Slide

393. View Slide

394. View Slide

395. Code Session
     265
     

     View Slide

396. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     ApplicationContext context
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     } 266
     

     View Slide

397. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     267
     

     View Slide

398. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     268
     

     View Slide

399. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     268
     

     View Slide

400. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     269
     

     View Slide

401. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     269
     

     View Slide

402. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     270
     

     View Slide

403. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     271
     

     View Slide

404. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     271
     

     View Slide

405. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     272
     

     View Slide

406. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     272
     

     View Slide

407. @Autowired
     public DefaultMessageService(
     MessageRepository messageRepository,
     ChatService chatClient,
     MessageBroker messageBroker
     ) {
     this.chatClient = chatClient;
     chatClient.stream()
     .transform(MessageMapper::toDomainUnits)
     .transform(messageRepository::saveAll)
     .subscribe()
     messageBroker.createChannel(
     "statisticChanged",
     saved.materialize()
     );
     }
     .transform()
     273
     

     View Slide

408. @Override
     public Flux latest() {
     return chatClient.stream()
     .transform(MessageMapper
     ::toViewModelUnits
     );
     }
     @Override
     public Flux latest() {
     return chatClient.stream()
     .transform(MessageMapper
     ::toViewModelUnits
     );
     }
     @Override
     public Flux latest() {
     return chatClient.stream()
     .transform(MessageMapper
     ::toViewModelUnits
     );
     }
     .transform()
     274
     

     View Slide

409. @Override
     public Flux latest() {
     return chatClient.stream()
     .transform(MessageMapper
     ::toViewModelUnits
     );
     }
     .transform()
     274
     

     View Slide

410. Statistics Service
     275
     

     View Slide

411. View Slide

412. View Slide

413. Code Session
     277
     

     View Slide

414. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 278
     

     View Slide

415. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 279
     

     View Slide

416. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 279
     

     View Slide

417. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 280
     

     View Slide

418. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 280
     

     View Slide

419. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 281
     

     View Slide

420. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 282
     

     View Slide

421. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 282
     

     View Slide

422. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 283
     

     View Slide

423. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     283
     

     View Slide

424. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     284
     

     View Slide

425. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     285
     

     View Slide

426. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 285
     

     View Slide

427. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…) 286
     

     View Slide

428. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     286
     

     View Slide

429. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     287
     

     View Slide

430. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     287
     

     View Slide

431. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     288
     

     View Slide

432. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     289
     

     View Slide

433. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     289
     

     View Slide

434. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     290
     

     View Slide

435. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     290
     

     View Slide

436. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     291
     

     View Slide

437. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     291
     

     View Slide

438. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     292
     

     View Slide

439. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     null
     292
     

     View Slide

440. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .map(…)
     .defaultIfEmpty(…)
     .zip(…)
     293
     

     View Slide

441. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     293
     

     View Slide

442. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     294
     

     View Slide

443. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     295
     

     View Slide

444. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     295
     

     View Slide

445. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     296
     

     View Slide

446. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     296
     

     View Slide

447. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     297
     

     View Slide

448. private Mono doGetUserStatistic
     Mono topActiveUser =
     userRepository
     .findMostActive()
     .map(UserMapper::toViewModelUnits);
     Mono topMentionedUser =
     userRepository
     .findMostPopular()
     .map(UserMapper::toViewModelUnits);
     return Mono.zip(
     topActiveUser.defaultIfEmpty(EMPTY_USER),
     topMentionedUser.defaultIfEmpty(EMPTY_USER),
     UsersStatisticVM::new
     );
     }
     .defaultIfEmpty(…)
     .zip(…)
     .subscribe()
     297
     

     View Slide

449. Reactive Endpoints
     298
     

     View Slide

450. View Slide

451. View Slide

452. Reactive WebSocket
     Out-of-the-box
     300
     

     View Slide

453. public interface WebSocketSession {
     String getId();
     HandshakeInfo getHandshakeInfo();
     DataBufferFactory bufferFactory();
     Flux receive();
     Mono send(Publisher messages);
     default Mono close() {
     return close(CloseStatus.NORMAL);
     }
     Mono close(CloseStatus status);
     WebSocketMessage textMessage(String payload);
     WebSocketMessage binaryMessage(
     Function payloadFactory);
     WebSocketMessage pingMessage(
     Function payloadFactory);
     WebSocketMessage pongMessage(
     Function payloadFactory);
     } 301
     

     View Slide

454. public interface WebSocketSession {
     String getId();
     HandshakeInfo getHandshakeInfo();
     DataBufferFactory bufferFactory();
     Flux receive();
     Mono send(Publisher messages);
     default Mono close() {
     return close(CloseStatus.NORMAL);
     }
     Mono close(CloseStatus status);
     WebSocketMessage textMessage(String payload);
     WebSocketMessage binaryMessage(
     Function payloadFactory);
     WebSocketMessage pingMessage(
     Function payloadFactory);
     WebSocketMessage pongMessage(
     Function payloadFactory);
     } 302
     

     View Slide

455. public interface WebSocketSession {
     String getId();
     HandshakeInfo getHandshakeInfo();
     DataBufferFactory bufferFactory();
     Flux receive();
     Mono send(Publisher messages);
     default Mono close() {
     return close(CloseStatus.NORMAL);
     }
     Mono close(CloseStatus status);
     WebSocketMessage textMessage(String payload);
     WebSocketMessage binaryMessage(
     Function payloadFactory);
     WebSocketMessage pingMessage(
     Function payloadFactory);
     WebSocketMessage pongMessage(
     Function payloadFactory);
     } 303
     

     View Slide

456. Code Session
     304
     

     View Slide

457. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     305
     

     View Slide

458. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     306
     

     View Slide

459. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     306
     

     View Slide

460. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     307
     

     View Slide

461. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     308
     

     View Slide

462. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     308
     

     View Slide

463. .merge()
     @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     309
     

     View Slide

464. .merge()
     @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     309
     

     View Slide

465. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     310
     

     View Slide

466. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     310
     

     View Slide

467. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     311
     

     View Slide

468. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     312
     

     View Slide

469. @Override
     public Publisher> handle(
     Publisher in
     ) {
     return Flux.merge(
     messageService.latest(),
     statisticService
     .usersStatisticStream()
     );
     }
     network
     .merge()
     312
     

     View Slide

470. New
     Reactive Architecture
     313
     

     View Slide

471. View Slide

472. View Slide

473. Demo
     315
     

     View Slide

474. https://goo.gl/XcnEnr
     316
     

     View Slide

475. Checklist
     • Message-Driven
     • Resilient
     • Responsive
     • Elastic
     317
     

     View Slide

476. Checklist
     • Message-Driven
     • Resilient
     • Responsive
     • Elastic
     317
     

     View Slide

477. Checklist
     • Message-Driven
     • Resilient
     • Responsive
     • Elastic
     317
     

     View Slide

478. Checklist
     • Message-Driven
     • Resilient
     • Responsive
     • Elastic
     317
     

     View Slide

479. Checklist
     • Message-Driven
     • Resilient
     • Responsive
     • Elastic
     317
     

     View Slide

480. Summary
     318
     

     View Slide

481. Q&A
     319
     

     View Slide

482. Resources
     1. Why Reactive? [http://www.oreilly.com/programming/
     free/why-reactive.csp]
     2. Operator Fusion Part 1 [http://akarnokd.blogspot.com/
     2016/03/operator-fusion-part-1.html]
     3. Reactive Streams Specification [http://www.reactive-
     streams.org/]
     4. Learn Project Reactor [http://projectreactor.io/learn]
     320
     

     View Slide

483. Thank you!
     321
     

     View Slide