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The Value of Reactive

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VMware Tanzu

Reactive programming enhances application efficiency through non-blocking operations, allowing for greater scalability and resilience. By utilizing frameworks like Spring WebFlux and Reactor, developers can manage multiple connections with reduced resource consumption and improved error handling. The document highlights key advantages, including reduced memory usage, lower costs, and successful isolation of traffic flows to enhance developer experience and application performance.

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The Value Of Reactive Stephane Maldini - Reactive Engineering @ Pivotal @smaldini
The Value Of Reactive What is it ? Where is the value ?
3 No, I do not have a medium blog =+ @smaldini
Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related) 😴
5 You
A reactive API primer 6 @GetMapping("/health") public Mono<Health> compositeHealth() { return Mono.zip( webClient.get() .uri(“https://alpha-service/health") .retrieve() .bodyToMono(Health.class), webClient.get() .uri("https://bravo-service/health") .retrieve() .bodyToMono(Health.class), (alpha, bravo) -> composite(alpha, bravo)) .switchIfEmpty(emptyComposite()); }
Is declarative style too disruptive to scale across dev teams ? 7
Debugging Reactive flows 8 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
Debugging Reactive flows 9 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] … You ?
Using blocking code in reactive callbacks 10 TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody();
Using blocking code in reactive callbacks 11 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); 💩
What are you priorities ? 12
What are you priorities ? 13 Time To Market / Dev Productivity
What are you priorities ? 14 Time To Market / Dev Productivity Day 2 Operations / Observability
What are you priorities ? 15 Time To Market / Dev Productivity Day 2 Operations / Observability […]
What are you priorities ? 16 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
What are you priorities ? 17 Time To Market / Dev Productivity Day 2 Operations / Observability Reactive ?Running costs / efficiency […]
Give me 18 Reasons To use this stuff
19 Order(s) of Magnitude 
 more efficient 🤑
• Lower Number of processes/threads used by instance • Lower Memory Pressure and associated costs (Garbage collectors) • Lower Hardware specification requirements • Lower Startup time 20 Order(s) of Magnitude 
 more efficient
Show me some numbers 21 Order(s) of Magnitude 
 more efficient
22 Order(s) of Magnitude 
 more efficient Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a simple hello world String rendering 128 / steps up to 4000 20s 20min
23 Order(s) of Magnitude 
 more efficient
24 Order(s) of Magnitude 
 more efficient MVCWebFlux
25 Order(s) of Magnitude 
 more efficient 😎 🤒
26 Order(s) of Magnitude 
 more efficient Moar Old Gen Moar Young Gen
27 Order(s) of Magnitude 
 more efficient
28 Order(s) of Magnitude 
 more efficient x2
29 Order(s) of Magnitude 
 more efficient 😎 ⏰
30 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
• Lower Number of instances running a same application • Lower Impact from traffic latency diversity • Lower Impact from persistent http traffic (websocket, sse, http2…) 31 Designed for 
 connection volume scalability
32 Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a 100ms delayed hello world String rendering 128 / steps up to 4000 20s 20min Designed for 
 connection volume scalability
Designed for 
 connection volume scalability 33 MVC (async)WebFlux
Designed for 
 connection volume scalability 34🤢
35 Designed for 
 connection volume scalability
36 x4 Designed for 
 connection volume scalability
37 ⏰⏰ Designed for 
 connection volume scalability
How does the response delay impact each model ? 38 Designed for 
 connection volume scalability
39 Designed for 
 connection volume scalability WebFlux WebFlux (with response delay)
WebFlux WebFlux (with response delay) 40 Designed for 
 connection volume scalability
WebFlux WebFlux (with response delay) 41 Designed for 
 connection volume scalability No major impact from backend delays
42 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC
43 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC Rapidly degrading running conditions
44 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay)
45 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay) x4 slower due to backend delays
46 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
47 Sleep Well,
 get less paged 📟 Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
Sleep Well,
 get less paged • Greater resilience to runtime errors, including memory issues • Greater availability at any point in time, specially under stress • Easier resources use modeling 48
Sleep Well,
 get less paged 49 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
Sleep Well,
 get less paged Reactive IO allows reading when application capacity permits 50
Sleep Well,
 get less paged Reactive IO only writes back application data when client capacity permits 51
52 WebFlux WebFlux (with response delay) Sleep Well,
 get less paged
53 WebFlux WebFlux (with response delay) Very similar resources use profile Sleep Well,
 get less paged
Sleep Well,
 get less paged 54 Can reactive programming help with JVM OutOfMemory exceptions caused by incoming request traffic ?
Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • A Connection Read causing an OutOfMemory will be rejected 55
Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • A Connection Read causing an OutOfMemory will be rejected • With a blocking IO runtime, request body overflow will be fatal • The entire application will crash or be in unrecoverable state 56
57 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
58 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability Event-Driven Less Threads - Memory Start quicker Improve Latency* Unlocks hyper concurrency Connected Experience Slow/Fast traffic Near-Always Available Flow Control Predictable load Resilient
59 What do you do with these qualities ? 🤓
60 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients
61 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients
62 Remote calls parallelization With Spring, you can start writing your app with WebMVC, introduce WebClient to improve backend calls workflows, then consider moving to WebFlux
63 Write an Edge API Available Traffic Control Volume of Connections
64 Write an Edge API Available Traffic Control Volume of Connections
65 Traffic Control A reactive runtime will isolate ingress/egress traffic latency and exceptions. Given this isolation property, a reactive Edge API should always be able to route traffic, even limit it or short-circuit when required.
66 Mobile Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
67 Mobile IoT Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
Ok sounds cool, but what about the developer experience ? 68 😷
69 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2 Actionable stacktraces
70 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
71 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled Reactive Developer productivity
72 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
73 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients Speaking of which…
74 BlockHound ! Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients https://github.com/reactor/BlockHound
Detecting blocking code in reactive stack 75 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
Detecting blocking code in reactive stack 76 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144] Quickly detect during pre-production workflows that will likely degrade your reactive stack experience
More reactive microservices ? 77 🤗
~80% of apps generated by start.spring.io are using a SQL driver 78
~80% of apps generated by start.spring.io are using a SQL driver 79 r2dbc.io
What should I look after I successfully have written my first Reactive apps ? 80
Monitoring with Micrometer 81 micrometer.io
82 Networking with RSocket rsocket.io
83 Having fun developing with Kotlin kotlinlang.org
So In Conclusion 84
What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You can actually be more productive in writing state of the art, scalable microservices
What are you priorities ? 86 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive Your Applications are designed to be resilient under stress and lower maintenance
What are you priorities ? 87 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You run more for less
What are you priorities ? 88 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
89 Establish the right project to experiment Reactive Programming with
90 Do it progressively, migrate a few dedicated backend routes then an entire application You can already parallelize some workloads even on your blocking stack
91
92 Use all the developers tools you can to accelerate your reactive adoption and build trust
93 Once the cost of learning has been paid and the benefits realized- it’s usually difficult to come back to blocking solutions.
94 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack.
95 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack. It’s just designed for them
THANK YOU @smaldini smaldini

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The Value of Reactive

  • 1. The Value Of Reactive Stephane Maldini - Reactive Engineering @ Pivotal @smaldini
  • 2. The Value Of Reactive What is it ? Where is the value ?
  • 3. 3 No, I do not have a medium blog =+ @smaldini
  • 4. Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related) 😴
  • 6. A reactive API primer 6 @GetMapping("/health") public Mono<Health> compositeHealth() { return Mono.zip( webClient.get() .uri(“https://alpha-service/health") .retrieve() .bodyToMono(Health.class), webClient.get() .uri("https://bravo-service/health") .retrieve() .bodyToMono(Health.class), (alpha, bravo) -> composite(alpha, bravo)) .switchIfEmpty(emptyComposite()); }
  • 7. Is declarative style too disruptive to scale across dev teams ? 7
  • 8. Debugging Reactive flows 8 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
  • 9. Debugging Reactive flows 9 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] … You ?
  • 10. Using blocking code in reactive callbacks 10 TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody();
  • 11. Using blocking code in reactive callbacks 11 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); 💩
  • 12. What are you priorities ? 12
  • 13. What are you priorities ? 13 Time To Market / Dev Productivity
  • 14. What are you priorities ? 14 Time To Market / Dev Productivity Day 2 Operations / Observability
  • 15. What are you priorities ? 15 Time To Market / Dev Productivity Day 2 Operations / Observability […]
  • 16. What are you priorities ? 16 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 17. What are you priorities ? 17 Time To Market / Dev Productivity Day 2 Operations / Observability Reactive ?Running costs / efficiency […]
  • 19. 19 Order(s) of Magnitude 
 more efficient 🤑
  • 20. • Lower Number of processes/threads used by instance • Lower Memory Pressure and associated costs (Garbage collectors) • Lower Hardware specification requirements • Lower Startup time 20 Order(s) of Magnitude 
 more efficient
  • 21. Show me some numbers 21 Order(s) of Magnitude 
 more efficient
  • 22. 22 Order(s) of Magnitude 
 more efficient Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a simple hello world String rendering 128 / steps up to 4000 20s 20min
  • 23. 23 Order(s) of Magnitude 
 more efficient
  • 24. 24 Order(s) of Magnitude 
 more efficient MVCWebFlux
  • 25. 25 Order(s) of Magnitude 
 more efficient 😎 🤒
  • 26. 26 Order(s) of Magnitude 
 more efficient Moar Old Gen Moar Young Gen
  • 27. 27 Order(s) of Magnitude 
 more efficient
  • 28. 28 Order(s) of Magnitude 
 more efficient x2
  • 29. 29 Order(s) of Magnitude 
 more efficient 😎 ⏰
  • 30. 30 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
  • 31. • Lower Number of instances running a same application • Lower Impact from traffic latency diversity • Lower Impact from persistent http traffic (websocket, sse, http2…) 31 Designed for 
 connection volume scalability
  • 32. 32 Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a 100ms delayed hello world String rendering 128 / steps up to 4000 20s 20min Designed for 
 connection volume scalability
  • 33. Designed for 
 connection volume scalability 33 MVC (async)WebFlux
  • 34. Designed for 
 connection volume scalability 34🤢
  • 35. 35 Designed for 
 connection volume scalability
  • 36. 36 x4 Designed for 
 connection volume scalability
  • 38. How does the response delay impact each model ? 38 Designed for 
 connection volume scalability
  • 39. 39 Designed for 
 connection volume scalability WebFlux WebFlux (with response delay)
  • 40. WebFlux WebFlux (with response delay) 40 Designed for 
 connection volume scalability
  • 41. WebFlux WebFlux (with response delay) 41 Designed for 
 connection volume scalability No major impact from backend delays
  • 42. 42 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC
  • 43. 43 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC Rapidly degrading running conditions
  • 44. 44 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay)
  • 45. 45 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay) x4 slower due to backend delays
  • 46. 46 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
  • 47. 47 Sleep Well,
 get less paged 📟 Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
  • 48. Sleep Well,
 get less paged • Greater resilience to runtime errors, including memory issues • Greater availability at any point in time, specially under stress • Easier resources use modeling 48
  • 49. Sleep Well,
 get less paged 49 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
  • 50. Sleep Well,
 get less paged Reactive IO allows reading when application capacity permits 50
  • 51. Sleep Well,
 get less paged Reactive IO only writes back application data when client capacity permits 51
  • 52. 52 WebFlux WebFlux (with response delay) Sleep Well,
 get less paged
  • 53. 53 WebFlux WebFlux (with response delay) Very similar resources use profile Sleep Well,
 get less paged
  • 54. Sleep Well,
 get less paged 54 Can reactive programming help with JVM OutOfMemory exceptions caused by incoming request traffic ?
  • 55. Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • A Connection Read causing an OutOfMemory will be rejected 55
  • 56. Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • A Connection Read causing an OutOfMemory will be rejected • With a blocking IO runtime, request body overflow will be fatal • The entire application will crash or be in unrecoverable state 56
  • 57. 57 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
  • 58. 58 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability Event-Driven Less Threads - Memory Start quicker Improve Latency* Unlocks hyper concurrency Connected Experience Slow/Fast traffic Near-Always Available Flow Control Predictable load Resilient
  • 59. 59 What do you do with these qualities ? 🤓
  • 60. 60 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients
  • 61. 61 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients
  • 62. 62 Remote calls parallelization With Spring, you can start writing your app with WebMVC, introduce WebClient to improve backend calls workflows, then consider moving to WebFlux
  • 63. 63 Write an Edge API Available Traffic Control Volume of Connections
  • 64. 64 Write an Edge API Available Traffic Control Volume of Connections
  • 65. 65 Traffic Control A reactive runtime will isolate ingress/egress traffic latency and exceptions. Given this isolation property, a reactive Edge API should always be able to route traffic, even limit it or short-circuit when required.
  • 66. 66 Mobile Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
  • 67. 67 Mobile IoT Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
  • 68. Ok sounds cool, but what about the developer experience ? 68 😷
  • 69. 69 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2 Actionable stacktraces
  • 70. 70 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
  • 71. 71 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled Reactive Developer productivity
  • 72. 72 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 73. 73 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients Speaking of which…
  • 74. 74 BlockHound ! Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients https://github.com/reactor/BlockHound
  • 75. Detecting blocking code in reactive stack 75 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
  • 76. Detecting blocking code in reactive stack 76 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144] Quickly detect during pre-production workflows that will likely degrade your reactive stack experience
  • 78. ~80% of apps generated by start.spring.io are using a SQL driver 78
  • 79. ~80% of apps generated by start.spring.io are using a SQL driver 79 r2dbc.io
  • 80. What should I look after I successfully have written my first Reactive apps ? 80
  • 83. 83 Having fun developing with Kotlin kotlinlang.org
  • 85. What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You can actually be more productive in writing state of the art, scalable microservices
  • 86. What are you priorities ? 86 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive Your Applications are designed to be resilient under stress and lower maintenance
  • 87. What are you priorities ? 87 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You run more for less
  • 88. What are you priorities ? 88 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 89. 89 Establish the right project to experiment Reactive Programming with
  • 90. 90 Do it progressively, migrate a few dedicated backend routes then an entire application You can already parallelize some workloads even on your blocking stack
  • 91. 91
  • 92. 92 Use all the developers tools you can to accelerate your reactive adoption and build trust
  • 93. 93 Once the cost of learning has been paid and the benefits realized- it’s usually difficult to come back to blocking solutions.
  • 94. 94 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack.
  • 95. 95 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack. It’s just designed for them