Taming WebSocket with Scarlet

Despite being a well-established standard for bidirectional persistent connection between client and server, WebSocket is complicated to set up on Android. When Tinder migrated to WebSocket for its realtime chat experience, they developed Scarlet: an extensible Kotlin library inspired by Retrofit that eliminates the boilerplate code required to handle data serialization and specify when to connect and retry. After this talk, you’ll be able to configure Scarlet using many of its plugins and integrate any WebSocket API in 10 minutes.

https://tech.gotinder.com/taming-websocket-with-scarlet/
https://github.com/Tinder/Scarlet
https://github.com/Tinder/StateMachine
#android #websocket

Transcript

1. Taming WebSocket with Scarlet Zhixuan Lai @zhxnlai github.com/zhxnlai
2. WebSocket
3. WebSocket • Supports text and binary messages
4. WebSocket • Supports text and binary messages • Realtime
5. WebSocket • Supports text and binary messages • Realtime • Efficient
6. WebSocket • Supports text and binary messages • Realtime • Efficient • Bidirectional
7. WebSocket
8. WebSocket // Create WebSocket connection. const socket = new WebSocket('ws://localhost:8080'); // Connection opened socket.addEventListener('open', function (event) { socket.send('Hello Server!'); }); // Listen for messages socket.addEventListener('message', function (event) { console.log('Message from server', data); });
9. WebSocket // Create WebSocket connection. const socket = new WebSocket('ws://localhost:8080'); // Connection opened socket.addEventListener('open', function (event) { socket.send('Hello Server!'); }); // Listen for messages socket.addEventListener('message', function (event) { console.log('Message from server', data); });
10. WebSocket // Create WebSocket connection. const socket = new WebSocket('ws://localhost:8080'); // Connection opened socket.addEventListener('open', function (event) { socket.send('Hello Server!'); }); // Listen for messages socket.addEventListener('message', function (event) { console.log('Message from server', data); });
11. WebSocket // Create WebSocket connection. const socket = new WebSocket('ws://localhost:8080'); // Connection opened socket.addEventListener('open', function (event) { socket.send('Hello Server!'); }); // Listen for messages socket.addEventListener('message', function (event) { console.log('Message from server', data); });
12. WebSocket // Create WebSocket connection. const socket = new WebSocket('ws://localhost:8080'); // Connection opened socket.addEventListener('open', function (event) { socket.send('Hello Server!'); }); // Listen for messages socket.addEventListener('message', function (event) { console.log('Message from server’, event.data); });
13. Use Cases
14. Use Cases • Chat • Multiplayer Games • Realtime Feed
15. WebSocket vs REST
16. WebSocket vs REST • Do we need it?
17. WebSocket vs REST • Bitcoin trading
18. Bitcoin Trading
19. Bitcoin Trading • Buy low and sell high
20. Bitcoin Trading • Buy low and sell high • React to market movement
21. Bitcoin Trading • Buy low and sell high • React to market movement • Realtime bitcoin price
22. Bitcoin Trading
23. data class Ticker( val time: String, val price: String ) Bitcoin Trading
24. data class Ticker( val time: String, val price: String ) Bitcoin Trading
25. GDAX Ticker
26. GDAX Ticker • REST API • WebSocket API
27. GDAX Ticker REST API
28. GDAX Ticker REST API interface GdaxRESTApi { @GET(“/products/{product-id}/ticker") ): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
29. GDAX Ticker REST API interface GdaxRESTApi { @GET(“/products/{product-id}/ticker") ): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
30. GDAX Ticker REST API interface GdaxRESTApi { } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
31. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/{product-id}/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
32. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
33. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>()
34. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>() gdaxRESTApi.getTicker() .subscribe { Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
35. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>() gdaxRESTApi.getTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) }
36. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>() gdaxRESTApi.getTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) }
37. GDAX Ticker REST API interface GdaxRESTApi { @GET("/products/BTC-USD/ticker") fun getTicker(): Flowable<Ticker> } val gdaxRESTApi = retrofit.create<GdaxRESTApi>() gdaxRESTApi.getTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) } // "Bitcoin price is $7600.01 at 2018-06-09T16:46:57.458Z”
38. GDAX Ticker REST API
39. GDAX Ticker REST API • Polling
40. Polling GDAX Ticker
41. Polling GDAX Ticker • Delay
42. Polling GDAX Ticker • Delay • Overhead
43. Polling GDAX Ticker • Delay • Overhead • Wasteful
44. GDAX Ticker WebSocket API
45. GDAX Ticker WebSocket API • Pushing • Realtime • Efficient
46. What’s wrong with WebSocket?
47. What’s wrong with WebSocket? • Difficult to set up
48. What’s wrong with WebSocket? • Difficult to set up • Boilerplate code
49. What’s wrong with WebSocket? • Difficult to set up • Boilerplate code • State management headache
50. What’s wrong with WebSocket? • Difficult to set up • Boilerplate code • State management headache • Difficult to maintain
51. What’s wrong with WebSocket? • Difficult to set up • Boilerplate code • State management headache • Difficult to maintain • Server API changes
52. What’s wrong with WebSocket? • Difficult to set up • Boilerplate code • State management headache • Difficult to maintain • Server API changes • Tech stack migration
53. Why Scarlet?
54. Why Scarlet? • Easy to get started
55. Why Scarlet? • Easy to get started • Easy to maintain
56. Why Scarlet? • Easy to get started • Easy to maintain • Reliable
57. Getting Started with Scarlet • GDAX WebSocket API
58. GDAX WebSocket API
59. GDAX WebSocket API • REST: request and response
60. GDAX WebSocket API • REST: request and response • WebSocket: bidirectional messages
61. GDAX WebSocket API • REST: request and response • WebSocket: bidirectional messages • Send Subscribe on connection open to stream Ticker
62. WebSocket with Scarlet
63. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
64. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
65. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
66. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
67. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
68. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>()
69. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( val type: String = "subscribe", @Json(name = "product_ids") val productIds: List<String>, val channels: List<String> )
70. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( val type: String, val productIds: List<String>, val channels: List<String> )
71. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... )
72. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = Subscribe( type = "subscribe", productIds = listOf("BTC-USD"), channels = listOf("ticker") )
73. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = Subscribe( type = "subscribe", productIds = listOf("BTC-USD"), channels = listOf("ticker") )
74. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = // ...
75. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = // ... val gdaxService = scarlet.create<GdaxWebSocketService>()
76. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = // ... val gdaxService = // ...
77. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = // ... val gdaxService = // ... gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE)
78. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... } data class Subscribe( // ... ) val BITCOIN_TICKER_SUBSCRIBE_MESSAGE = // ... val gdaxService = // ... gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE)
79. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) // ... }
80. WebSocket with Scarlet interface GdaxWebSocketService { // ... }
81. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> }
82. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.OnConnectionOpen<*>> }
83. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> }
84. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> } gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) }
85. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> } gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) }
86. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> } gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) }
87. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> }
88. WebSocket with Scarlet interface GdaxWebSocketService { // ... }
89. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> }
90. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> }
91. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> }
92. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
93. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
94. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) }
95. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) } // "Bitcoin price is $7600.01 at 2018-06-09T16:46:57.458Z"
96. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) } // "Bitcoin price is $7600.01 at 2018-06-09T16:46:57.458Z" // "Bitcoin price is $7600.85 at 2018-06-09T16:46:58.033Z"
97. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is \$${ticker.price} at ${ticker.time}”) } // "Bitcoin price is $7600.01 at 2018-06-09T16:46:57.458Z" // "Bitcoin price is $7600.85 at 2018-06-09T16:46:58.033Z" // "Bitcoin price is $7601.62 at 2018-06-09T16:46:58.610Z”
98. WebSocket with Scarlet interface GdaxWebSocketService { // ... @Receive fun observeTicker(): Flowable<Ticker> }
99. WebSocket with Scarlet interface GdaxWebSocketService { // ... }
100. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> }
101. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> }
102. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = scarlet.create<GdaxWebSocketService>() gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
103. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = // ... gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
104. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = // ... gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
105. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = // ... gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
106. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = // ... gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
107. WebSocket with Scarlet interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> } val gdaxService = // ... gdaxService.observeOnConnectionOpenedEvent() .subscribe { gdaxService.sendSubscribe(BITCOIN_TICKER_SUBSCRIBE_MESSAGE) } gdaxService.observeTicker() .subscribe { ticker -> Log.d("Bitcoin price is ${ticker.price} at ${ticker.time}") }
108. Scarlet Plugins
109. Scarlet Plugins • Built-in with OkHttp, Moshi, Gson, Protobuf, RxJava
110. Scarlet Plugins • Built-in with OkHttp, Moshi, Gson, Protobuf, RxJava • Roadmap: Jackson, xml, LiveData, Java 9 Flow, and more
111. Scarlet Plugins • Built-in with OkHttp, Moshi, Gson, Protobuf, RxJava • Roadmap: Jackson, xml, LiveData, Java 9 Flow, and more • Fully customizable
112. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
113. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
114. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
115. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
116. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
117. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
118. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
119. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
120. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
121. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
122. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
123. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
124. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
125. WebSocketFactory
126. WebSocketFactory • Supports any WebSocket implementation
127. WebSocketFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
128. WebSocketFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(MockHttpServer().newWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
129. WebSocketFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
130. WebSocketFactory (Roadmap)
131. WebSocketFactory (Roadmap) •java-websocket •java.net.socket
132. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
133. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
134. MessageAdapterFactory
135. MessageAdapterFactory • Text and binary messages
136. MessageAdapterFactory • Text and binary messages • Serialization & deserialization of any type •Subscribe •Ticker
137. MessageAdapterFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
138. MessageAdapterFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(GsonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
139. MessageAdapterFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(ProtobufMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
140. MessageAdapterFactory (Roadmap) const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
141. MessageAdapterFactory (Roadmap) const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(XmlMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
142. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(XmlMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
143. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(XmlMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
144. StreamAdapter
145. StreamAdapter • Stream • Sequence of asynchronous values
146. StreamAdapter • Stream • Sequence of asynchronous values • Scarlet Stream
147. StreamAdapter • Stream • Sequence of asynchronous values • Scarlet Stream • Converts Scarlet Stream into other abstractions
148. StreamAdapterFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
149. StreamAdapterFactory const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava1StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
150. StreamAdapterFactory (Roadmap) const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(LiveDataStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
151. StreamAdapterFactory (Roadmap) const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(Java9FlowStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
152. StreamAdapterFactory (Roadmap) const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(KotlinCoroutineStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
153. Scarlet Plugins const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(KotlinCoroutineStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
154. Maintaining Scarlet
155. Maintaining Scarlet • Easy to maintain
156. Supporting API Changes • Receiving Level 2
157. Supporting API Changes { "type": "snapshot", "product_id": "BTC-USD", "bids": [["6500.11", "0.45054140"]], "asks": [["6500.15", "0.57753524"]] }
158. Supporting API Changes • Receiving Level 2
159. Supporting API Changes • Receiving Level 2 • 2 loc
160. Supporting API Changes interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
161. Supporting API Changes interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
162. Changing WebSocket Implementation
163. Changing WebSocket Implementation • Use a custom WebSocket implementation
164. Changing WebSocket Implementation • Use a custom WebSocket implementation • 1 loc
165. Changing WebSocket Implementation interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
166. Changing WebSocket Implementation interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
167. Changing JSON Library
168. Changing JSON Library • From Moshi to Jackson
169. Changing JSON Library • From Moshi to Jackson • 1 loc
170. Changing JSON Library interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
171. Changing JSON Library interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
172. Supporting Kotlin Coroutine
173. Supporting Kotlin Coroutine • From Flowable to Sequence
174. Supporting Kotlin Coroutine • From Flowable to Sequence • 3 loc
175. Supporting Kotlin Coroutine interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Flowable<Ticker> @Receive fun observeLevel2(): Flowable<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
176. Supporting Kotlin Coroutine interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Sequence<Ticker> @Receive fun observeLevel2(): Sequence<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
177. Supporting Kotlin Coroutine interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Sequence<Ticker> @Receive fun observeLevel2(): Sequence<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
178. Supporting Kotlin Coroutine interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Sequence<Ticker> @Receive fun observeLevel2(): Sequence<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(KotlinCoroutineStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
179. Supporting Kotlin Coroutine interface GdaxWebSocketService { @Send fun sendSubscribe(subscribe: Subscribe) @Receive fun observeOnConnectionOpenedEvent( ): Flowable<WebSocket.Event.OnConnectionOpen<*>> @Receive fun observeTicker(): Sequence<Ticker> @Receive fun observeLevel2(): Sequence<Level2> } val scarlet = Scarlet.Builder() .webSocketFactory(CustomWebSocketFactory()) .addMessageAdapterFactory(JacksonMessageAdapter.Factory()) .addStreamAdapterFactory(KotlinCoroutineStreamAdapter.Factory()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
180. Scarlet Reliability
181. Scarlet Reliability • Tested in production
182. Scarlet Reliability • Tested in production • 190 countries
183. Scarlet Reliability • Tested in production • 190 countries • 26 million matches every day
184. Scarlet Reliability • Tested in production • 190 countries • 26 million matches every day • Thousands of devices
185. WebSocket on Android
186. WebSocket on Android • Straightforward when the connection is open
187. WebSocket on Android • Straightforward when the connection is open • But a connection may fail
188. WebSocket on Android
189. WebSocket on Android • Unstable network
190. WebSocket on Android • Unstable network • Server closure
191. WebSocket on Android • Unstable network • Server closure • App enters background
192. WebSocket on Android
193. WebSocket on Android
194. WebSocket on Android
195. WebSocket on Android
196. WebSocket on Android
197. WebSocket on Android
198. WebSocket on Android
199. WebSocket on Android
200. WebSocket on Android
201. WebSocket on Android
202. WebSocket on Android
203. WebSocket on Android
204. WebSocket on Android
205. WebSocket on Android
206. State Management in Scarlet
207. State Management in Scarlet • Scarlet has got you covered
208. State Management in Scarlet
209. State Management in Scarlet • Reliable
210. State Management in Scarlet • Reliable • Testable and debuggable
211. State Management in Scarlet • Reliable • Testable and debuggable • Fully tested
212. What makes Scarlet testable?
213. What makes Scarlet testable? • Immutable State, Event and Transition • State Machine DSL
214. State Machine DSL
215. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
216. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
217. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
218. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
219. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
220. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
221. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
222. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
223. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
224. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
225. State Machine DSL sealed class State { object Solid : State() object Liquid : State() object Gas : State() } sealed class Event { object OnMelted : Event() object OnFroze : Event() object OnVaporized : Event() object OnCondensed : Event() }
226. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
227. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
228. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
229. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
230. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
231. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
232. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
233. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
234. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
235. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
236. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
237. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
238. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
239. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
240. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
241. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
242. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
243. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
244. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
245. State Machine DSL StateMachine.create<State, Event> { initialState(Solid) state<Solid> { on<OnMelted> { transitionTo(Liquid) } } state<Liquid> { on<OnFroze> { transitionTo(Solid) } on<OnVaporized> { transitionTo(Gas) } } state<Gas> { on<OnCondensed> { transitionTo(Liquid) } } }
246. Testing State Machine StateMachine.create<State, Event> { // ... }
247. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... }
248. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... } assertThat(stateMachine.state).isEqualTo(Solid) // When stateMachine.transition(OnMelted) // Then assertThat(stateMachine.state).isEqualTo(Liquid)
249. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... } assertThat(stateMachine.state).isEqualTo(Solid) // When stateMachine.transition(OnMelted) // Then assertThat(stateMachine.state).isEqualTo(Liquid)
250. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... } assertThat(stateMachine.state).isEqualTo(Solid) // When stateMachine.transition(OnMelted) // Then assertThat(stateMachine.state).isEqualTo(Liquid)
251. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... } assertThat(stateMachine.state).isEqualTo(Solid) // When stateMachine.transition(OnMelted) // Then assertThat(stateMachine.state).isEqualTo(Liquid)
252. Testing State Machine val stateMachine = StateMachine.create<State, Event> { // ... } assertThat(stateMachine.state).isEqualTo(Solid) // When stateMachine.transition(OnMelted) // Then assertThat(stateMachine.state).isEqualTo(Liquid)
253. State Machine in Scarlet
254. State Machine in Scarlet
255. State Management Plugins
256. State Management Plugins
257. State Management Plugins
258. State Management Plugins
259. State Management Plugins
260. State Management Plugins
261. State Management Plugins • Lifecycle • Declare when to connect and to keep retrying • Backoff Strategy • Declare when to retry
262. State Management in Scarlet
263. Scarlet
264. Scarlet • Easy to get started
265. Scarlet • Easy to get started • Declarative API
266. Scarlet • Easy to get started • Declarative API • Built-in plugins
267. Scarlet • Easy to get started • Declarative API • Built-in plugins • Customizable
268. Scarlet • Easy to get started • Declarative API • Built-in plugins • Customizable • Easy to maintain
269. Scarlet • Easy to get started • Declarative API • Built-in plugins • Customizable • Easy to maintain • Reliable
270. Scarlet • Easy to get started • Declarative API • Built-in plugins • Customizable • Easy to maintain • Reliable • StateMachine DSL
271. Scarlet • Easy to get started • Declarative API • Built-in plugins • Customizable • Easy to maintain • Reliable • StateMachine DSL • State management plugins
272. Taming WebSocket with Scarlet github.com/Tinder/Scarlet github.com/Tinder/StateMachine github.com/zhxnlai
273. Lifecycle const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(BACKOFF_STRATEGY) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
274. Lifecycle const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(BACKOFF_STRATEGY) .lifecycle(AndroidLifecycle.ofApplicationForeground()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
275. Lifecycle
276. Lifecycle • Started
277. Lifecycle • Started • Connect and keep retrying
278. Lifecycle • Started • Connect and keep retrying • Stopped
279. Lifecycle • Started • Connect and keep retrying • Stopped • Disconnect
280. Lifecycle
281. Lifecycle
282. Lifecycle
283. Lifecycle
284. Built-in Lifecycle AndroidLifecycle.ofApplicationForeground(application)
285. Write you own Lifecycle AndroidLifecycle.ofApplicationForeground(application) loggedInLifecycle
286. Combine Lifecycle AndroidLifecycle.ofApplicationForeground(application) .combineWith(loggedInLifecycle)
287. Combine Lifecycle fun createAppForegroundAndUserLoggedInLifecycle(): Lifecycle { return AndroidLifecycle.ofApplicationForeground(application) .combineWith(loggedInLifecycle) }
288. Combine Lifecycle fun createAppForegroundAndUserLoggedInLifecycle(): Lifecycle { return AndroidLifecycle.ofApplicationForeground(application) .combineWith(loggedInLifecycle) }
289. Lifecycle const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(BACKOFF_STRATEGY) .lifecycle(AndroidLifecycle.ofApplicationForeground()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
290. Lifecycle const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(BACKOFF_STRATEGY) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
291. Lifecycle const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(BACKOFF_STRATEGY) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
292. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(ExponentialWithJitterBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
293. Backoff Strategy
294. Backoff Strategy
295. Backoff Strategy • Declare when to retry
296. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(LinearBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
297. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(ExponentialBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
298. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(ExponentialWithJitterBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
299. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(CustomBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()
300. Backoff Strategy const val GDAX_URL = "wss://ws-feed.gdax.com" val scarlet = Scarlet.Builder() .webSocketFactory(okHttpClient.newWebSocketFactory(GDAX_URL)) .addMessageAdapterFactory(MoshiMessageAdapter.Factory()) .addStreamAdapterFactory(RxJava2StreamAdapter.Factory()) .backoffStrategy(CustomBackoffStrategy()) .lifecycle(createAppForegroundAndUserLoggedInLifecycle()) .build() val gdaxService = scarlet.create<GdaxWebSocketService>()