Spring MVC 4.x Spring 5 Web Reactive

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1 Part 1 Spring MVC 4.x Spring 5 Web Reactive Rossen

2 Spring MVC 4.3 Reactive programming for Java devs Spring 5 Web Reactive

3 Shortcut

8 @ApplicationScope

14 Not to be confused

16 @RestControllerAdvice

17 @ModelAttribute(binding=false)

18 Pre-load Foo in the model Form object with binding Foo object without binding

19 HTTP OPTIONS, HEAD automated handling

20 curl -v -X OPTIONS < < < < HTTP/ OK Server: Apache-Coyote/1.1 Allow: GET,HEAD Content-Length: 0

curl --head http://localhost:8080/foos/123 HTTP/1.

21 curl --head HTTP/ OK Server: Apache-Coyote/1.1 Content-Type: application/json;charset=utf-8 Content-Length: 155

22 ForwardedHeaderFilter

23 Complements existing support for X-Forwarded-* in [ Mvc Servlet ] UriComponentsBuilder

24 RestTemplate default URI variable values

26 Client Mock REST Tests expected count + order of requests

28 Spring MVC 4.3 Reactive programming for Java devs Spring 5 Web Reactive

29 Long Running Shift To Concurrency 29

30 Today Independent services 10 years ago Cloud environment Distributed apps Self-sufficient apps App server Keep it simple, don t distribute 30

31 Impact on Programming Model Imperative logic is not a simple path any more Forced to deal with asynchronicity Limits of scale 31

32 Fundamentally Asynchronous Async and non-blocking by design Small number of threads Efficient scale 32

33 Design async API with Java Futures 33

34 Return a Value

35 Usage 35

36 Return Value with Future... May be thrown in different thread 36

37 Usage Ugh 37

38 Return Value with CompletableFuture

39 Usage Async callback 39

40 Return Collection

41 Return Void

42 Return Void Success or Failure callback 42

43 CompletableFuture Fundamentally the right idea for use in async APIs Allows declarative composition of async logic Lambdas keep it readable 43

44 CompletableFuture Not ideal for Collection return values Nor for latency sensitive data sets Nor large or infinite data sets 44

45 Async return values as a stream?

46 onerror or oncomplete onnext onnext onnext 46

47 Return type Use case Notifications void Success oncomplete() void Failure onerror(throwable) User Match onnext(user), oncomplete() User No match oncomplete() User Failure onerror(throwable) List<User> Two matches onnext(user), onnext(user), oncomplete() List<User> No match oncomplete() List<User> Failure onerror(throwable)

48 Java 8 Stream Great example of the kind of API we d like Declarative composition of async logic per item Lambdas keep it readable 48

49 Java 8 Stream Built for collections Not for active or hot source of data Latency-sensitive data sequences 49

50 No single best fluent async API [...] Until now one missing category was "push" style operations on items as they become available from an active source. Doug Lea Reactive Streams & Java 9 initial announcement 50

51 Reactive Streams Small API, spec rules, and TCK Publish-subscribe with back pressure Interoperability across async components and libraries 51

52 Project Reactor Reactive Streams library for the JVM Declarative operations on items similar to Java 8 Stream Flux and Mono reactive composable API types 52

53 Reactive Repository

54 Reactive Repository In Use

55 Example output onsubscribe request(unbounded) onnext(user: Jason) onnext(user: Jay)... oncomplete() By default consume without back-pressure

56 Part 2 Spring MVC 4.x Spring 5 Web Reactive Rossen

57 Spring MVC 4.3 Reactive programming for Java devs Spring 5 Web Reactive

58 Reactive Programming A style of micro-architecture Declarative, functional-style, composition of logic The opposite of imperative 58

59 Imperative / Blocking

60 Functional / Neutral to Asynchronicity

61 Thread Pool Style Processing 61

62 20 ms Server Threads 250 ms 50 ms 150 ms 15 ms 150 ms 15 ms Network Latency 150 ms 200 ms Network Latency Thread Pool Thread Pool Application Processing 75 ms 125 ms

63 Load Balancer Requests Requests Server Threads Server Threads Application Handling Application Handling

64 Event Loop Style Processing 64

65 20 ms IO selector 250 ms 50 ms 150 ms worker worker worker 200 ms 75 ms Application Processing 125 ms

66 Non-blocking Application pan.addwater(() -> range.lowerheat(() -> pan.addbrownrice(() -> pan.settimeout(() -> { range.turnoff(); // ready... }, Duration.ofMinutes(40)))));

67 Rise above the callbacks

68 ReactiveX DeclarativeFunctional, programming on Observable streams

69 Reactive Streams Specification Async stream processing with reactive back-pressure

70 Reactive Streams public interface Publisher<T> { void subscribe(subscriber<? super T> subscriber); } Backpressure public interface Subscriber<T> { void onsubscribe(subscription sub); void onnext(t item); void onerror(throwable ex); void oncomplete(); public interface Subscription { void request(long n); } void cancel(); } 70

71 Project Reactor Reactive Streams + ReactiveX

72 Reactor Mono

73 Reactor Flux

74 Reactive Repository

75 Reactive Repository in Use Subscriber triggers flow of data

76 Example output onsubscribe request(unbounded) onnext(user: Jason) onnext(user: Jay)... oncomplete() By default consume without back-pressure

77 Consume Two Items at a Time

78 Example output onsubscribe request(2) onnext(user: Jason) onnext(user: Jay) request(2) onnext(user: Joe) onnext(user: John)... Producer complies with back-pressure

79 Spring MVC 4.3 Reactive programming for Java devs Spring 5 Web Reactive

80 Spring Data Reactive

81 Spring Data Reactive

82 Reactive Processing Pipeline HTTP Server Web Framework Controller End-to-end back-pressure Repository

83 Reactive Web Controller

84 Reactive Web Controller Sp rin g 5

85 Reactive Web Controller / RxJava Sp rin g 5

86 Router Functions Spring Web MVC Spring Web Reactive Servlet API Reactive HTTP Servlet Container Tomcat, Jetty, Servlet 3.1+, Netty, Undertow

87 Reactive HTTP Adaptation

88 Reactive HTTP Server Adaptation Tomcat, Jetty, Servlet 3.1+ containers Netty (Reactor Netty, RxNetty) Undertow

89 Reactive Encoder and Decoder Serialization to/from Flux<T> and Flux<DataBuffer> JSON (Jackson) and XML (JAXB / Aalto) Server-Sent Events Resource with zero-copy file transfer

90 Spring Web Reactive Along with Spring Web MVC Operates on reactive HTTP request / response Shared algorithms and mechanisms

91 Non-Blocking HTTP GET Synchronous, non-blocking method Async, non-blocking method

92 Non-Blocking HTTP POST or

93 Server-Sent Events

94 Zero-Copy File Transfer

95 WebClient

96 WebClient / RxJava

97 Non-blocking WebClient Scatter/Gather

98 Functional Web Framework No annotations, minimal, and transparent Same reactive foundation "Spring 5: Functional Web Framework" blog post

99 Functional-style Web Routing

100

101 Spring Boot Web Reactive Starter Helpful instructions:

102 Manual Bootstrap Only a few lines of code: Spring Framework 5.0 snapshot reference

Spring Framework 5.0 Reactive Web Application

2017 2016 Pivotal Software, Inc. All rights reserved. # Spring Framework 5.0 Reactive Web Application Toshiaki Maki (@making) 2016-05-17 Java Day Tokyo 2017 Who am I? Toshiaki Maki (@making) https://blog.ik.am