Simple HTTP with Retrofit 2 (Droidcon NYC 2015)

Retrofit has been simplifying HTTP calls for years and this new version is no different. In addition to fixing some long-standing annoyances, there are a handful of new features which make it more powerful than ever.

This talk will focus on how the new APIs in Retrofit aid in making HTTP calls as simple as possible for your app. The integration with OkHttp and Okio APIs will be covered to ensure a full understanding of the HTTP stack. Common use-cases and design patterns through more advanced functionality will end the talk.

No prior Retrofit, OkHttp, or Okio exposure needed. The content may quickly cover or skip some introductory aspects in order to allow focus on more actionable and useful content.

Video: https://youtu.be/KIAoQbAu3eA

Transcript

1. Retrofit Two Jake Wharton
2. Retrofit 2 will be out by the end of this year " " — Naïve Man
3. Retrofit 2 will be out by the end of this year " " — Jake Wharton
4. Retrofit 2 will be out by the end of this year " " Droidcon NYC 2014 — Jake Wharton
5. Retrofit 2 will be out by the end of this year " " Droidcon NYC 2015 — Jake Wharton
6. Retrofit 1
7. Retrofit 1 • Made open source on October 13th, 2010
8. Retrofit 1 • Made open source on October 13th, 2010 • Originally a Bob Lee joint
9. Retrofit 1 • Made open source on October 13th, 2010 • Originally a Bob Lee joint • Took over / stole stewardship mid-2012
10. Retrofit 1 • Made open source on October 13th, 2010 • Originally a Bob Lee joint • Took over / stole stewardship mid-2012 • Released 1.0 on May 13th, 2013
11. Retrofit 1 • Made open source on October 13th, 2010 • Originally a Bob Lee joint • Took over / stole stewardship mid-2012 • Released 1.0 on May 13th, 2013 • 18 releases post-1.0 with tons of features / fixes
12. The Good
13. The Good • Interface service declarations • Method and parameter annotations customize request
14. Interface and annotations interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
15. The Good • Interface service declarations • Method and parameter annotations customize request • Pluggable HTTP client and serialization
16. Pluggable client and serialization builder.setClient(new UrlConnectionClient()); builder.setClient(new ApacheClient()); builder.setClient(new OkClient());
17. Pluggable client and serialization builder.setClient(new UrlConnectionClient()); builder.setClient(new ApacheClient()); builder.setClient(new OkClient()); builder.setClient(new CustomClient());
18. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
19. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } builder.setConverter(new GsonConverter()); builder.setConverter(new JacksonConverter());
20. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 ContributorResponse repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
21. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 ContributorResponse repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } builder.setConverter(new ProtoConverter()); builder.setConverter(new WireConverter());
22. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 ContributorResponse repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } builder.setConverter(new ProtoConverter()); builder.setConverter(new WireConverter()); builder.setConverter(new SimpleXMLConverter());
23. Pluggable client and serialization interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 ContributorResponse repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } builder.setConverter(new ProtoConverter()); builder.setConverter(new WireConverter()); builder.setConverter(new SimpleXMLConverter()); builder.setConverter(new CustomConverter());
24. The Good • Interface service declarations • Method and parameter annotations customize request • Pluggable HTTP client and serialization • Synchronous, asynchronous, and RxJava execution
25. Sync, async, and RxJava interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } List<Contributor> contributors = gitHubService.repoContributors("square", "retrofit");
26. Sync, async, and RxJava interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 void repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo,
 Callback<List<Contributor>> cb);
 } service.repoContributors("square", "retrofit", new Callback<List<Contributor>>() {
 @Override void success(List<Contributor> contributors, Response response) {
 // ...
 }
 
 @Override void failure(RetrofitError error) {
 // ...
 }
 });
27. Sync, async, and RxJava interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } gitHubService.repoContributors("square", "retrofit")
 .subscribe(new Action1<List<Contributor>>() {
 @Override public void call(List<Contributor> contributors) {
 // ...
 }
 });
28. The Good • Interface service declarations • Method and parameter annotations customize request • Pluggable HTTP client and serialization • Synchronous, asynchronous, and RxJava execution
29. The Not-So-Good
30. The Not-So-Good • Request/Response (and friends) model classes
31. Request/Response model classes
32. The Not-So-Good • Request/Response (and friends) model classes • No access to serialized body and response data
33. No access to body and response interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
34. No access to body and response interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 @GET("/repos/{owner}/{repo}/contributors")
 Response repoContributors2(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
35. The Not-So-Good • Request/Response (and friends) model classes • No access to serialized body and response data • Rigid execution mechanisms
36. Rigid execution mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo); @GET("/repos/{owner}/{repo}/contributors")
 void repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo,
 Callback<List<Contributor>> cb);
 }
37. Rigid execution mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
38. Rigid execution mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 ListenableFuture<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
39. Rigid execution mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 CompletableFuture<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
40. The Not-So-Good • Request/Response (and friends) model classes • No access to serialized body and response data • Rigid execution mechanisms • Inefficient converter usage
41. Inefficient converter usage interface Converter {
 Object fromBody(TypedInput body, Type type);
 TypedOutput toBody(Object object);
 }
42. Inefficient converter usage interface Converter {
 Object fromBody(TypedInput body, Type type);
 TypedOutput toBody(Object object);
 } Type TypeAdapter TypedInput/Output JsonAdapter ObjectReader/Writer Parser ProtoAdapter
43. Inefficient converter usage interface Converter {
 Object fromBody(TypedInput body, Type type);
 TypedOutput toBody(Object object);
 } Type TypeAdapter TypedInput/Output JsonAdapter ObjectReader/Writer Parser ProtoAdapter
44. The Not-So-Good • Request/Response (and friends) model classes • No access to serialized body and response data • Rigid execution mechanisms • Inefficient converter usage • Simple custom parameter types support
45. Simple custom parameter types interface GitHubService {
 @GET("/search/repositories")
 RepositoriesResponse searchRepos(
 @Query("q") String query,
 @Query("since") Date since);
 }X
46. Simple custom parameter types interface GitHubService {
 @GET("/search/repositories")
 RepositoriesResponse searchRepos(
 @Query("q") String query,
 @Query("since") Date since);
 }X /search/repositories?q=retrofit&since=2015-08-27
47. Simple custom parameter types interface GitHubService {
 @GET("/search/repositories")
 RepositoriesResponse searchRepos(
 @Query("q") String query,
 @Query("since") Date since);
 }X /search/repositories?q=retrofit&since=2015-08-27 /search/repositories?q=retrofit&since=20150827
48. The Not-So-Good • Request/Response (and friends) model classes • No access to serialized body and response data • Rigid execution mechanisms • Inefficient converter usage • Simple custom parameter types support
49. Retrofit 2
50. Retrofit 2 • Call encapsulates single request/response interaction
51. Call • Models a single request/response pair
52. Call • Models a single request/response pair • Separates request creation from response handling
53. Call • Models a single request/response pair • Separates request creation from response handling • Each instance can only be used once...
54. Call • Models a single request/response pair • Separates request creation from response handling • Each instance can only be used once... • ...instances can be cloned
55. Call • Models a single request/response pair • Separates request creation from response handling • Each instance can only be used once... • ...instances can be cloned • Supports both synchronous and asynchronous execution.
56. Call • Models a single request/response pair • Separates request creation from response handling • Each instance can only be used once... • ...instances can be cloned • Supports both synchronous and asynchronous execution. • Can be (actually) canceled
57. Call interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 List<Contributor> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo); }X
58. Call interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
59. Call interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
60. Call interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit");
61. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit");
62. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); 
 response = call.execute();
63. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); 
 response = call.execute(); // This will throw IllegalStateException:
 response = call.execute();
64. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); 
 response = call.execute(); // This will throw IllegalStateException:
 response = call.execute(); Call<List<Contributor>> call2 = call.clone();
 // This will not throw:
 response = call2.execute();
65. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit");
66. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); 
 call.enqueue(new Callback<List<Contributor>>() {
 @Override void onResponse(/* ... */) {
 // ...
 }
 
 @Override void onFailure(Throwable t) {
 // ...
 }
 });
67. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); call.enqueue( ); // or... call.execute();
68. Call Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); call.enqueue( ); // or... call.execute(); // later... call.cancel();
69. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object
70. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); response = call.execute();
71. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); Response<List<Contributor>> response = call.execute();
72. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); Response<List<Contributor>> response = call.execute();
73. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); call.enqueue(new Callback<List<Contributor>>() {
 @Override void onResponse(/* ... */) {
 // ...
 }X
 
 @Override void failure(Throwable t) {
 // ...
 }X
 });
74. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); call.enqueue(new Callback<List<Contributor>>() {
 @Override void onResponse(Response<List<Contributor>> response) {
 // ...
 }X
 
 @Override void failure(Throwable t) {
 // ...
 }X
 });
75. Response Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); call.enqueue(new Callback<List<Contributor>>() {
 @Override void onResponse(Response<List<Contributor>> response) {
 // ...
 }
 
 @Override void failure(Throwable t) {
 // ...
 }
 });
76. Response class Response<T> {
 }X
77. Response class Response<T> {
 int code();
 String message(); Headers headers();
 }X
78. Response class Response<T> {
 int code();
 String message(); Headers headers();
 
 boolean isSuccess();
 }X
79. Response class Response<T> {
 int code();
 String message(); Headers headers();
 
 boolean isSuccess(); T body();
 ResponseBody errorBody();
 }X
80. Response class Response<T> {
 int code();
 String message(); Headers headers();
 
 boolean isSuccess(); T body();
 ResponseBody errorBody(); com.squareup.okhttp.Response raw();
 }X
81. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object
82. If it isn't broken...
83. Fixed Query Param interface SomeService {
 @GET("/some/endpoint?fixed=query")
 Call<SomeResponse> someEndpoint();
 } someService.someEndpoint(); // GET /some/endpoint?fixed=query HTTP/1.1
84. Dynamic Query Param interface SomeService {
 @GET("/some/endpoint")
 Call<SomeResponse> someEndpoint(
 @Query("dynamic") String dynamic);
 } someService.someEndpoint("query"); // GET /some/endpoint?dynamic=query HTTP/1.1
85. Dynamic Query Param Map interface SomeService {
 @GET("/some/endpoint")
 Call<SomeResponse> someEndpoint(
 @QueryMap Map<String, String> dynamic);
 } someService.someEndpoint( Collections.singletonMap("dynamic", "query")); // GET /some/endpoint?dynamic=query HTTP/1.1
86. Omit Dynamic Query Param interface SomeService {
 @GET("/some/endpoint")
 Call<SomeResponse> someEndpoint(
 @Query("dynamic") String dynamic);
 } someService.someEndpoint(null); // GET /some/endpoint HTTP/1.1
87. Fixed+Dynamic Query Params interface SomeService {
 @GET("/some/endpoint?fixed=query")
 Call<SomeResponse> someEndpoint(
 @Query("dynamic") String dynamic);
 } someService.someEndpoint("query"); // GET /some/endpoint?fixed=query&dynamic=query HTTP/1.1
88. Path Replacement interface SomeService {
 @GET("/some/endpoint/{foo}")
 Call<SomeResponse> someEndpoint(
 @Path("thing") String thing);
 } someService.someEndpoint("bar"); // GET /some/endpoint/bar HTTP/1.1
89. Fixed Header interface SomeService {
 @GET("/some/endpoint") @Headers("Accept-Encoding: application/json")
 Call<SomeResponse> someEndpoint();
 } someService.someEndpoint(); // GET /some/endpoint HTTP/1.1 // Accept-Encoding: application/json
90. Dynamic Header interface SomeService {
 @GET("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Header("Location") String location);
 } someService.someEndpoint("Droidcon NYC 2015"); // GET /some/endpoint HTTP/1.1 // Location: Droidcon NYC 2015
91. Omit Dynamic Header interface SomeService {
 @GET("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Header("Location") String location);
 } someService.someEndpoint(null); // GET /some/endpoint HTTP/1.1
92. Fixed+Dynamic Header interface SomeService {
 @GET("/some/endpoint") @Headers("Accept-Encoding: application/json")
 Call<SomeResponse> someEndpoint( @Header("Location") String location);
 } someService.someEndpoint("Droidcon NYC 2015"); // GET /some/endpoint HTTP/1.1 // Accept-Encoding: application/json // Location: Droidcon NYC 2015
93. Post Without Body interface SomeService {
 @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint();
 } someService.someEndpoint(); // POST /some/endpoint?fixed=query HTTP/1.1 // Content-Length: 0
94. Post With Body interface SomeService {
 @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Body SomeRequest body);
 } someService.someEndpoint(); // POST /some/endpoint HTTP/1.1 // Content-Length: 3 // Content-Type: greeting // // Hi!
95. Form Encoded Fields interface SomeService {
 @FormUrlEncoded @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Field("name1") String name1, @Field("name2") String name2);
 } someService.someEndpoint("value1", "value2"); // POST /some/endpoint HTTP/1.1 // Content-Length: 25 // Content-Type: application/x-www-form-urlencoded // // name1=value1&name2=value2
96. Omit Form Encoded Field interface SomeService {
 @FormUrlEncoded @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Field("name1") String name1, @Field("name2") String name2);
 } someService.someEndpoint("value1", null); // POST /some/endpoint HTTP/1.1 // Content-Length: 12 // Content-Type: application/x-www-form-urlencoded // // name1=value1
97. Form Encoded Field Map interface SomeService {
 @FormUrlEncoded @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @FieldMap Map<String, String> names);
 } someService.someEndpoint( ImmutableMap.of("name1", "value1", "name2", "value2")); // POST /some/endpoint HTTP/1.1 // Content-Length: 25 // Content-Type: application/x-www-form-urlencoded // // name1=value1&name2=value2
98. Multipart Parts interface SomeService {
 @Multipart @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Part("name1") String name1, @Part("name2") String name2);
 } someService.someEndpoint("value1", "value2"); // POST /some/endpoint HTTP/1.1 // Content-Length: 102 // Content-Type: application/form-data // // ...
99. Omit Multipart Part interface SomeService {
 @Multipart @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @Part("name1") String name1, @Part("name2") String name2);
 } someService.someEndpoint("value1", null); // POST /some/endpoint HTTP/1.1 // Content-Length: 56 // Content-Type: application/form-data // // ...
100. Multipart Part Map interface SomeService {
 @Multipart @POST("/some/endpoint")
 Call<SomeResponse> someEndpoint( @PartMap Map<String, String> names);
 } someService.someEndpoint( ImmutableMap.of("name1", "value1", "name2", "value2")); // POST /some/endpoint HTTP/1.1 // Content-Length: 102 // Content-Type: application/form-data // // ...
101. If it isn't broken...
102. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object • Dynamic URL parameter
103. Dynamic URL interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
104. Dynamic URL interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); Response<List<Contributor>> response = call.execute();
105. Dynamic URL interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } Call<List<Contributor>> call = gitHubService.repoContributors("square", "retrofit"); Response<List<Contributor>> response = call.execute(); // HTTP/1.1 200 OK // Link: <https://api.github.com/repositories/892275/contributors? page=2>; rel="next", <https://api.github.com/repositories/892275/ contributors?page=3>; rel="last" // ...
106. Dynamic URL Response<List<Contributor>> response = call.execute(); // HTTP/1.1 200 OK // Link: <https://api.github.com/repositories/892275/contributors? page=2>; rel="next", <https://api.github.com/repositories/892275/ contributors?page=3>; rel="last" // ...
107. Dynamic URL Response<List<Contributor>> response = call.execute(); // HTTP/1.1 200 OK // Link: <https://api.github.com/repositories/892275/contributors? page=2>; rel="next", <https://api.github.com/repositories/892275/ contributors?page=3>; rel="last" // ... String links = response.headers().get("Link");
108. Dynamic URL Response<List<Contributor>> response = call.execute(); // HTTP/1.1 200 OK // Link: <https://api.github.com/repositories/892275/contributors? page=2>; rel="next", <https://api.github.com/repositories/892275/ contributors?page=3>; rel="last" // ... String links = response.headers().get("Link"); String nextLink = nextFromGitHubLinks(links);
109. Dynamic URL Response<List<Contributor>> response = call.execute(); // HTTP/1.1 200 OK // Link: <https://api.github.com/repositories/892275/contributors? page=2>; rel="next", <https://api.github.com/repositories/892275/ contributors?page=3>; rel="last" // ... String links = response.headers().get("Link"); String nextLink = nextFromGitHubLinks(links); // https://api.github.com/repositories/892275/contributors?page=2
110. Dynamic URL interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
111. Dynamic URL interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo); 
 @GET
 Call<List<Contributor>> repoContributorsPaginate(
 @Url String url);
 }X
112. Dynamic URL String nextLink = nextFromGitHubLinks(links); // https://api.github.com/repositories/892275/contributors?page=2
113. Dynamic URL String nextLink = nextFromGitHubLinks(links); // https://api.github.com/repositories/892275/contributors?page=2 Call<List<Contributor>> nextCall = gitHubService.repoContributorsPaginate(nextLink);
114. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object • Dynamic URL parameter • Multiple, efficient converters
115. Converters interface SomeProtoService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); }X interface SomeJsonService {
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X
116. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X 
 
 SomeProtoResponse
117. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeProtoResponse
118. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeProtoResponse Proto? Yes!
119. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeJsonResponse
120. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeJsonResponse Proto? No!
121. Converters interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeJsonResponse Proto? No! JSON? Yes!
122. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object • Dynamic URL parameter • Multiple, efficient converters • Multiple, pluggable execution mechanisms
123. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
124. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(
 @Path("owner") String owner,
 @Path("repo") String repo); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
125. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Call
126. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Call
127. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Call RxJava? No!
128. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Call RxJava? No! Call? Yes!
129. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Observable
130. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Observable RxJava? Yes!
131. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Future
132. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Future RxJava? No!
133. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Future RxJava? No! Call? No!
134. Execution Mechanisms interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Future<List<Contributor>> repoContributors3(..);
 }X Future RxJava? No! Call? No! Throw!
135. Retrofit 2 • Call encapsulates single request/response interaction • Parameterized Response object • Dynamic URL parameter • Multiple, efficient converters • Multiple, pluggable execution mechanisms
136. Powered by OkHttp
137. Powered by OkHttp • In 2012 we needed client abstractions.
138. Powered by OkHttp • In 2012 we needed client abstractions. • In 2012 we needed request/response abstractions.
139. Powered by OkHttp • In 2012 we needed client abstractions. • In 2012 we needed request/response abstractions. • In 2012 we needed header abstractions.
140. Powered by OkHttp • In 2012 we needed client abstractions. • In 2012 we needed request/response abstractions. • In 2012 we needed header abstractions. • It's 2015. OkHttp is small, lean, focused, and full-featured.
141. Powered by OkHttp
142. Powered by OkHttp & Okio bit.ly/ok-libs
143. Retrofit
144. Retrofit OkHttp
145. Retrofit OkHttp Socket
146. Retrofit OkHttp BufferedSource BufferedSink Socket
147. Retrofit OkHttp BufferedSource BufferedSink RequestBody ResponseBody Socket
148. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody Socket
149. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody Socket Moshi
150. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody Socket Moshi BufferedSink BufferedSource <T>
151. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> RequestBody ResponseBody Socket Moshi BufferedSink BufferedSource <T>
152. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket Moshi BufferedSink BufferedSource <T>
153. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket myEndpoint() Moshi BufferedSink BufferedSource <T>
154. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
155. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
156. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
157. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
158. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
159. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
160. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
161. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
162. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
163. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
164. Retrofit OkHttp MoshiConverter BufferedSource BufferedSink RequestBody ResponseBody <T> MyService RequestBody ResponseBody Socket execute() myEndpoint() Moshi BufferedSink BufferedSource <T>
165. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build();
166. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
167. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } GitHubService gitHubService = retrofit.create(GitHubService.class);
168. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/repos/square/retrofit/contributors
169. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/repos/square/retrofit/contributors HttpUrl
170. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/repos/square/retrofit/contributors HttpUrl .resolve()
171. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
172. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
173. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
174. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/repos/square/retrofit/contributors
175. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/repos/square/retrofit/contributors HttpUrl .resolve()
176. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
177. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }X
178. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 }
179. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com/v3/") .build(); interface GitHubService {
 @GET("repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(
 @Path("owner") String owner,
 @Path("repo") String repo);
 } // https://api.github.com/v3/repos/square/retrofit/contributors
180. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build();
181. Setup OkHttpClient client = new OkHttpClient(); Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .client(client) .build();
182. Setup OkHttpClient client = new OkHttpClient(); client.interceptors().add(..); Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .client(client) .build();
183. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .build();
184. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .addConverterFactory(GsonConverterFactory.create()) .build();
185. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .addConverterFactory(GsonConverterFactory.create()) .addConverterFactory(ProtoConverterFactory.create()) .build();
186. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .addConverterFactory(ProtoConverterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build();
187. Setup Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.github.com") .addConverterFactory(ProtoConverterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) .build();
188. Extensibility • Converter.Factory • CallAdapter.Factory
189. Converter.Factory interface SomeService {
 @GET("/some/proto/endpoint")
 Call<SomeProtoResponse> someProtoEndpoint(); 
 @GET("/some/json/endpoint")
 Call<SomeJsonResponse> someJsonEndpoint();
 }X SomeJsonResponse Proto? No! JSON? Yes!
190. Converter.Factory interface Converter<T> { interface Factory { Converter<?> create(Type type); } }X SomeJsonResponse Proto? No! JSON? Yes!
191. Converter.Factory SomeJsonResponse Proto? No! JSON? Yes!
192. Converter.Factory class ProtoConverterFactory { Converter<?> create(Type type); }X SomeJsonResponse null No! JSON? Yes!
193. JSON Converter.Factory class ProtoConverterFactory { Converter<?> create(Type type); }X SomeJsonResponse null No! Converter<?> Yes! class GsonConverterFactory { Converter<?> create(Type type); }X
194. Converter.Factory interface Converter<T> { interface Factory { Converter<?> create(Type type); }X }X
195. Converter.Factory interface Converter<T> { interface Factory { Converter<?> create(Type type); }X T fromBody(ResponseBody body); RequestBody toBody(T value); }X
196. Extensibility • Converter.Factory • CallAdapter.Factory
197. CallAdapter.Factory interface GitHubService {
 @GET("/repos/{owner}/{repo}/contributors")
 Call<List<Contributor>> repoContributors(..); 
 @GET("/repos/{owner}/{repo}/contributors")
 Observable<List<Contributor>> repoContributors2(..);
 }X Call RxJava? No! Call? Yes!
198. CallAdapter.Factory interface CallAdapter<T> { interface Factory { CallAdapter<?> create(Type type); }
 }X Call RxJava? No! Call? Yes!
199. CallAdapter.Factory Call RxJava? No! Call? Yes!
200. CallAdapter.Factory Call Call? Yes! class RxJavaCallAdapterFactory { CallAdapter<?> create(Type type); }X null No!
201. CallAdapter.Factory Call class RxJavaCallAdapterFactory { CallAdapter<?> create(Type type); }X null No! JSON CallAdapter<?> Yes! class CallAdapterFactory { CallAdapter<?> create(Type type); }X
202. CallAdapter.Factory interface CallAdapter<T> { interface Factory { CallAdapter<?> create(Type type); }X }X
203. CallAdapter.Factory interface CallAdapter<T> { interface Factory { CallAdapter<?> create(Type type); }X Type responseType(); Object adapt(Call<T> value); }X
204. Extensibility • Converter.Factory • CallAdapter.Factory
205. Under Construction
206. Under Construction • Parameter handlers
207. Under Construction • Parameter handlers • Logging?
208. Under Construction • Parameter handlers • Logging? • Finalizing mock module
209. Under Construction • Parameter handlers • Logging? • Finalizing mock module • Documentation
210. Under Construction • Parameter handlers • Logging? • Finalizing mock module • Documentation • WebSockets! (in v2.1)
211. Release?
212. Release? dependencies {
 compile 'com.squareup.retrofit:retrofit:2.0.0-beta1' compile 'com.squareup.retrofit:converter-gson:2.0.0-beta1' compile 'com.squareup.retrofit:adapter-rxjava:2.0.0-beta1' }
213. jakewharton jakewharton twitter.com/ google.com/+ .com Retrofit Two jakewharton