gRPC with Kotlin Coroutines on Android

Learn about how to use gRPC on Android.

Transcript

1. Mohit Sarveiya gRPC with Kotlin Coroutines on Android @heyitsmohit
2. gRPC with Kotlin Coroutines • Using gRPC on Android • Authentication • Retries & Hedging • Debugging tools
3. RPC g RPC (Remote Procedure Call) Framework
4. • Polyglot implementation • Coroutines Support gRPC
5. Server(Go) gRPC Client(Kotlin) Client(Swift)
6. Server(Go) gRPC service Client(Kotlin) Client(Swift)
7. Server(Go) gRPC service service MyService { rpc subscribe( . . ) }
8. • Unary RPC call • Server streaming • Client streaming • Bidirectional streaming RPC Calls
9. gRPC service MyService { rpc subscribe( . . ) } Proto buffer file Protoc Service Class
10. • Generated class • Handles incoming requests • Send back data Service Class
11. Server(Go) gRPC service Client(Kotlin) Client(Swift)
12. Server(Go) gRPC service Client(Kotlin) Client(Swift) service service
13. gRPC service MyService { rpc subscribe( . . ) } Proto buffer file Protoc Client Stub
14. • Generated class. • Make Requests. • Creates response types. Client Stub
15. Server(Go) gRPC service Client(Kotlin) Client(Swift) Client Stub
16. Server(Go) gRPC service Client(Kotlin) Client(Swift) rpc rpc
17. Server(Go) gRPC service Client(Kotlin) Client(Swift) rpc rpc HTTP 2
18. Android gRPC Server
19. grpc/grpc-kotlin Code ! Issues Pull Requests gRPC-Kotlin/JVM - An RPC library and framework grpc-kotlin-stub v0.1.4 protoc-gen-grpc-kotlinstub v0.1.4 grpc-kotlin-stub-lite v0.1.4 Bazel Build passing Gradle Build passing A Kotlin/JVM implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first.
20. Use Case • Tracks your route.
21. Use Case • Tracks your route. • Get a place from location.
22. Use Case • Tracks your route. • Get a place from location. • List Places around location.
23. Use Case • Tracks your route. • Get a place from location. • List Places around location. • Chat with others at location. Shoreline Golf links 2940 N Shoreline Blvd Mountain View, CA 94043 Start typing
24. Android gRPC Server gRPC
25. gRPC service service MyService { rpc subscribe( . . ) } gRPC Server
26. protocolbuffers/protobuf Code ! Issues Pull Requests Protocol Buffers - Google’s data interchange format Protocol Buffers (a.k.a., protobuf) are Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data. Gradle Build passing
27. Service syntax = “proto3”; Protocol Buffer Version
28. Service syntax = “proto3”; service Places { } Declare Service
29. RPC Call Types • Unary • Server Streaming • Client Streaming • Bidirectional
30. Use Case • Get a place from location 
 (Latitude, Longitude) Place
31. Unary RPC Call Client Server Location
32. syntax = “proto3”; service Places { rpc GetPlace(Location) returns (Place) {}; } Unary RPC Call keyword
33. Unary RPC Call Name of RPC call service Places { rpc GetPlace() }
34. Unary RPC Call service Places { rpc GetPlace(Location) } Request
35. Unary RPC Call service Places { rpc GetPlace(Location) returns (Place) {}; } Response
36. Unary RPC Call syntax = “proto3”; service Places { rpc GetPlace(Location) returns (Place) {}; } Unary RPC Call
37. Unary RPC Call syntax = “proto3”; service Places { rpc GetPlace(Location) returns (Place) {}; } Define messages
38. Unary RPC Call message Location { double latitude = 1; double longitude = 2; } } Keyword
39. Unary RPC Call service Places { message Location double latitude = 1; double longitude = 2; } } Message name
40. Unary RPC Call message Location { double latitude = 1; double longitude = 2; } Fields
41. message Location { double latitude = 1; double longitude = 2; } Unary RPC Call Type
42. message Location { double latitude = 1; double longitude = 2; } Unary RPC Call .proto Type C++ Java Go double double Double * f l oat64 int32 int32 int *int32 Int64 long int/long *int64 https://developers.google.com/protocol-bu f f ers/docs/overview#scalar
43. message Location { double latitude = 1; double longitude = 2; } Unary RPC Call Field numbers
44. Unary RPC Call syntax = “proto3”; service Places { rpc GetPlace(Location) returns (Place) {}; } Define Place
45. Unary RPC Call message Place { string name = 1; Location location = 2; } Name & Location
46. Unary RPC Call message Place { string name = 1; Location location = 2; 
 PlaceType placeType = 3; } Enum
47. Unary RPC Call message Place { 
 PlaceType placeType = 3; enum PlaceType { Landmark = 0; Driving_Range = 1; Golf_Course = 2; Restaurant = 3; Retail = 4; } Enum
48. Unary RPC Call message Place { string name = 1; Location location = 2; 
 PlaceType placeType = 3; enum PlaceType { … } 
 int64 checkins = 4; int64 comments = 5; } Int Scaler Types
49. Unary RPC Call syntax = “proto3”; service Places { rpc GetPlace(Location) returns (Place) {}; }
50. Use Case • Check into place 
 Location Empty Response
51. Unary RPC Call syntax = “proto3”; service Places { rpc CheckIn(Location) returns () {}; }
52. Unary RPC Call syntax = “proto3”; service Places { rpc CheckIn(Location) returns () {}; } How do we return an empty?
53. Code ! Issues Pull Requests protocolbuffers/protobuf protobuf/src/google/protobuf/empty.proto message Empty { }
54. Well Known Types • Empty • Timestamp • Duration
55. Unary RPC Call syntax = “proto3”; 
 import "google/protobuf/empty.proto"; service Places { rpc CheckIn(Place) returns () {}; } Import
56. Unary RPC Call syntax = “proto3”; service Places { rpc CheckIn(Location) returns (google.protobuf.Empty) {}; } How do we return an empty?
57. RPC Call Types • Unary • Server Streaming • Client Streaming • Bidirectional
58. Use Case • List Places around location. Location(s) List<Place>
59. Server Streaming Client Server Location(s)
60. Server Streaming Client Server Stream of Places
61. Server Streaming service Places { rpc ListPlaces(Area) returns (stream Place) {}; } Server Streaming RPC Call
62. Server Streaming service Places { rpc ListPlaces(Area) returns (stream Place) {}; } Cluster of Locations
63. Server Streaming message Area { Location lo = 1; Location hi = 2; 
 } Cluster of Locations
64. Server Streaming service Places { rpc ListPlaces(Area) returns (stream Place) {}; } stream keyword
65. Server Streaming service Places { rpc ListPlaces(Area) returns (stream Place) {}; } Server Streaming RPC Call
66. RPC Call Types • Unary • Server Streaming • Client Streaming • Bidirectional
67. Use Case • Tracks your route Location(s) 
 Trip Summary
68. Client Streaming Client Server Location(s)
69. Client Streaming Client Server Trip Summary
70. Client Streaming service Places { rpc RecordTrip(stream Location) returns (TripSummary) {}; }
71. Client Streaming service Places { rpc RecordTrip(stream Location) returns (TripSummary) {}; } Client Stream
72. Client Streaming service Places { rpc RecordTrip(stream Location) returns (TripSummary) {}; } Return single message
73. Client Streaming service Places { rpc RecordTrip(stream Location) returns (TripSummary) {}; }
74. RPC Call Types • Unary • Server Streaming • Client Streaming • Bidirectional
75. Use Case • Chat with others at location • Stream of messages Shoreline Golf links 2940 N Shoreline Blvd Mountain View, CA 94043 Start typing
76. Bidirectional RPC Call Client Server Comments
77. Bidirectional RPC Call Client Server Replies
78. Bidirectional RPC Call service Places { rpc Chat(stream Comment) returns (stream Comment) {}; } Bidirectional RPC Call
79. Bidirectional RPC Call service Places { rpc Chat(stream Comment) returns (stream Comment) {}; } stream keyword
80. RPC Call Types • Unary • Server Streaming • Client Streaming • Bidirectional
81. RPC Call Types service Places { rpc GetPlace(Location) returns (Place) {}; rpc ListPlaces(Area) returns (stream Place) {}; rpc CheckIn(Place) returns (google.protobuf.Empty) {}; rpc Chat(stream Comment) returns (stream Comment) {}; }
82. gRPC service MyService { rpc subscribe( . . ) } gRPC Server Service
83. Android gRPC Server gRPC Service Service
84. Android gRPC Client Stub
85. Generating Client Stub • Class for messages • Coroutine bindings for rpc calls
86. Generating Builders Proto buffer file Protoc Message Builders class Message { static class Builder { Builder set(double value) Location build() } }
87. Creating Messages message Location { double latitude = 1; double longitude = 2; } class Location { static class Builder { Builder setLatitude(double value) Builder setLongitude(double value) Location build() } }
88. Creating Messages message Location { double latitude = 1; double longitude = 2; } Location.newBuilder() .setLatitude(40.9888341) .setLongitude(-73.8502007) .build()
89. protocolbuffers/protobuf Code ! Issues Pull Requests Kotlin support request #3742 ! Open issue opened on Oct 12, 2017 comment on opened on Oct 12, 2017 Please support convert to Kotlin 168
90. Generating Service Proto buffer file Protoc Service class Service { fun rpcMethod1(): Flow<Message> 
 fun rpcMethod2(): Flow<Message> }
91. Generated Client class CoroutineStub { }
92. Generated Client class CoroutineStub { } rpc GetPlace(Location) returns (Place) {};
93. Generated Client class CoroutineStub { } rpc GetPlace(Location) returns (Place) {}; suspend fun getPlace(request: Location): Place
94. Generated Client class CoroutineStub { } rpc ListPlaces(Area) returns (stream Place) {};
95. Generated Client class CoroutineStub { } rpc ListPlaces(Area) returns (stream Place) {}; fun listPlaces(request: Area): Flow<Place> Stream is map to Flow
96. Generated Client class CoroutineStub { } rpc Chat(stream Comment) returns (stream Comment) {};
97. Generated Client class CoroutineStub { } rpc Chat(stream Comment) returns (stream Comment) {}; fun chat(requests: Flow<Comment>): Flow<Comment> Stream is map to Flow
98. Generated Client class CoroutineStub { } suspend fun getPlace(request: Location): Place fun recordTrip(requests: Flow<Location>): TripSummary fun listPlaces(request: Area): Flow<Place> fun chat(requests: Flow<Comment>): Flow<Comment>
99. • Create Managed Channel • Specify server url, port • Create Client Stub Using Client
100. Using Client val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() .build()
101. Using Client val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() .build() Specify host and port
102. Using Client val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() for https
103. Using Client val managedChannel = ManagedChannelBuilder .intercept(object : ClientInterceptor { fun interceptCall(method, callOptions, channel) { }) Intercept RPC Calls
104. Using Client val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() .build()
105. Using Client val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() .build() val client = CoroutineStub(managedChannel)
106. View Model gRPC Client Stub
107. Using Client class GrpcViewModel(val client: CoroutineStub): ViewModel() { }
108. Unary RPC Call class CoroutineStub { } suspend fun getPlace(request: Location): Place
109. Unary RPC Call fun getPlace(location: Location) { viewModelScope.launch { } }
110. Unary RPC Call fun getPlace(location: Location) { viewModelScope.launch { val place = client.getPlace(location) } }
111. Unary RPC Call fun getPlace(location: Location) { viewModelScope.launch { withContext(Dispatchers.IO) { val place = client.getPlace(location) } } }
112. Server Streaming class CoroutineStub { } fun listPlaces(request: Area): Flow<Place>
113. Server Streaming fun listPlaces(area: Area) { }
114. Server Streaming fun listPlaces(area: Area) { viewModelScope.launch { } }
115. Server Streaming fun listPlaces(area: Area) { viewModelScope.launch { val places: Flow<Place> = client.listPlaces(area) } }
116. Server Streaming fun listPlaces(area: Area) { viewModelScope.launch { val places: Flow<Place> = client.listPlaces(area) places.collect { } } }
117. Bidirectional RPC Call class CoroutineStub { } fun chat(requests: Flow<Comment>): Flow<Comment>
118. Bidirectional RPC Call class CoroutineStub { } fun chat(requests: Flow<Comment>): Flow<Comment>
119. Bidirectional RPC Call Client Stub Comments
120. Bidirectional RPC Call State Flow Comments
121. Bidirectional RPC Call State Flow Comments Comments Client Stub
122. Using Client fun chat(comments: Flow<Comment>) { } Stream of comments
123. Using Client fun chat(comments: Flow<Comment>) { viewModelScope.launch { } } } }
124. Using Client fun chat(comments: Flow<Comment>) { viewModelScope.launch { client.chat(comments) } } } }
125. Using Client fun chat(comments: Flow<Comment>) { viewModelScope.launch { client.chat(comments) .collect { } } } }
126. Using Client class GrpcViewModel(val client: CoroutineStub): ViewModel() { fun getPlace(location: Location) fun listPlaces(area: Area): Flow<Place> fun chat(chat: Flow<Comment>) }
127. gRPC Client Stub How does it use coroutines?
128. Consumer Coroutine
129. gRPC-java client Start Consumer Coroutine
130. gRPC-java client Request Consumer Coroutine Producer Coroutine Response
131. gRPC-java client Request Consumer Coroutine Producer Coroutine Response Channel (size = 1)
132. gRPC-java client Request Consumer Coroutine Producer Coroutine Response Channel (size = 1)
133. gRPC-java client Request Consumer Coroutine Producer Coroutine Response Channel (size = 1) Flow<Response>
134. gRPC Client Stub How does it use coroutines?
135. Android gRPC Client Stub Auth
136. Auth Methods • JWT Token • Certificate Auth • HTTP Basic Auth
137. Auth Client Server RPC Call
138. Auth Client Server Metadata
139. Auth Metadata headers = new Metadata();
140. Auth Metadata headers = new Metadata(); headers.put(“auth_token","token");
141. Auth val client = CoroutineStub(managedChannel)
142. Auth val client = CoroutineStub(managedChannel) .withCallCredentials( . . . )
143. withCallCredentials(object: CallCredentials { override fun applyRequestMetadata() { } } Auth
144. withCallCredentials(object: CallCredentials { override fun applyRequestMetadata(applier: MetadataApplier) { } } Auth
145. withCallCredentials(object: CallCredentials { override fun applyRequestMetadata(applier: MetadataApplier) { Metadata headers = new Metadata(); headers.put(“auth_token","token"); } } Auth
146. withCallCredentials(object: CallCredentials { override fun applyRequestMetadata(applier: MetadataApplier) { Metadata headers = new Metadata(); headers.put(“auth_token","token"); applier.apply(headers); } } Auth
147. Auth Client Server RPC Call
148. Auth Client Server Metadata
149. Errors Client Server RPC Call
150. Errors Client Server Retry
151. Enable Retry val managedChannel = ManagedChannelBuilder .forAddress(host, port) .useTransportSecurity() .enableRetry() .build()
152. Client App gRPC Client Lib Server Application
153. Client App gRPC Client Lib Server Application Make 
 gRPC Call Sends RPC
154. Client App gRPC Client Lib Server Application Failure Make 
 gRPC Call Sends RPC
155. Client App gRPC Client Lib Server Application Failure Make 
 gRPC Call Sends RPC Returns UNAVAILABLE
156. Client App gRPC Client Lib Server Application Failure Make 
 gRPC Call Sends RPC Returns UNAVAILABLE Retried RPC
157. Client App gRPC Client Lib Server Application Failure Make 
 gRPC Call Sends RPC Returns UNAVAILABLE Retried RPC Success Return OK Receive 
 data
158. Enable Retry "retryPolicy": { "maxAttempts": 10, "initialBackoff": "5s", "maxBackoff": "1s", "backoffMultiplier": 2, "retryableStatusCodes": [ "UNAVAILABLE" ] }
159. Hedging Client Server RPC Call(s)
160. Client App gRPC Client Lib Server Application Make 
 gRPC Call Sends RPC
161. Client App gRPC Client Lib Server Application Make 
 gRPC Call Sends RPC Return OK
162. Client App gRPC Client Lib Server Application Make 
 gRPC Call Sends RPC Cancel
163. Hedging Policy "hedgingPolicy": { "maxAttempts": 10, "hedgingDelay": “1.5s", "nonFatalStatusCodes": [ "UNAVAILABLE", "INTERNAL", "ABORTED" ] }
164. uw-labs/bloom-rpc Code ! Issues Pull Requests BloomRPC The missing GUI Client for GRPC services. release v1.5.2
166. gRPC https: / / codingwithmohit.com/grpc/grpc-kotlin-coroutines/
167. Resources • gRPC with Kotlin Coroutines 
 
 https: / / codingwithmohit.com/grpc/grpc-kotlin-coroutines/ • Unit Testing Delays, Errors & Retries with Kotlin Flows 
 
 https: / / codingwithmohit.com/coroutines/unit-testing-delays- 
 errors-retries-with-kotlin-flows/ 
 

168. Thank You! www.codingwithmohit.com @heyitsmohit