介紹近年在各語言都火熱的 Reactive Programming 架構與其特性，並透過 Rx.Net 展示如何實作於.Net Core的開發中，帶來更多架構的選擇與彈性。 Lab: https://github.com/blackie1019/reactive-progamming-dot-net

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Learn. Imagine. Build.
.NET Conf
響應式程式開發之 .NET Core 應用
(Reactive Programming with .NET Core)
Blackie Tsai

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這場不會深入的討論如何把
Code 寫好寫滿

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主要是介紹
Reactive Programming

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並透過實際展示，認識
Reactive Programming

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Reactive Programming
是一種編碼風格

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讓我們用一種更合適的方式
撰寫某些情境的程式

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介紹
Reactive Programming
展示
更多 Reactive
上手
Rx.NET
介紹
Reactive Extensions

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(https://blackie1019.github.io/)
.NET JAVASCRIPT

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什麼是
Reactive Programming?

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int a = 2;
int b = 3;
int c = a + b;
Console. WriteLine("before: the value of c is {0}",c);
a=2;
b=7;
Console. WriteLine("after: the value of c is {0}",c);
以下程式結果為何?

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before: the value of c is 5
after: the value of c is 5
正常來說…

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before: the value of c is 5
after: the value of c is 9
但有時候我們期望能出現以下結果

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Reactive Programming 是
學習如何與周遭事件進行非
同步開發

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Reactive Programming 是
學習將事件當作資料流
(Stream)進行操作

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當到此資料流結束
發生一個錯誤
某一個click event
時間

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Again, 什麼是
Reactive Programming?

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Console.Write("Press input A:");
var a = Convert.ToInt32(Console.ReadLine());
Console.Write("Press input B:");
var b = Convert.ToInt32(Console.ReadLine());
var c = a+b;
Console.WriteLine("before: the value of c is {0}",c);
Console.Write("Press input B again:");
b = Convert.ToInt32(Console.ReadLine());
c = a+b;
Console.WriteLine("after: the value of c is {0}",c);
Imperative programming

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while (true)
{
Console.Write("Press input A:");
var a = Convert.ToInt32(Console.ReadLine());
Console.Write("Press input B:");
var subscription = Observable
.FromAsync(() => Console.In.ReadLineAsync())
.Subscribe(b => Console.WriteLine("the value of c is
{0}",a+Convert.ToInt32(b)));
Console.Write("enter symbol (or x to exit): ");
…
}
Reactive programming

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為什麼要考慮使用Reactive
Programming?

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https://www.reactivemanifesto.org/
Message Driven
透過非同步訊息溝通達到模組隔離
與委託處理
Responsive
系統在任何情況下，都能及時響應
Resilient
系統在異常時，具有容錯性
Elastic
系統能依據需求彈性拓展

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再繼續講主題前，讓我們離
題一下認識 Functional
Programming

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C# 範例
Building building = SomeQueryThatShouldReturnBuilding();
var phoneNumber = null;
// Object-Oriented Programming
if(building != null){
if(building.Manager.ContactInfo != null){
if(building.Manager.ContactInfo.PhoneNumber != null){
phoneNumber = building.Manager.ContactInfo.PhoneNumber;
}
}
}
// Functional Programming
phoneNumber = SomeQueryThatShouldReturnBuilding()
.With(b=>b.Manager)
.With(m=>m.ContactInfo)
.With(c=>c.PhoneNumber);

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[1, 4, 9].map(Math.sqrt).map(
function(x){
return x + 1
}
);
=> [2, 3, 4]
JavaScript 範例

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Object-Oriented Programming Functional Programming
程式開發抽象的核心 資料結構 函式
資料與操作的關係 緊耦合 鬆耦合
溝通方式 物件(Objects) 透過介面 函式(Functions)透過協定
是否有狀態 有狀態(Stateful) 無狀態(Stateless)
回應值是否透明、可預測 回應值由輸入與狀態確定 回應值總是由輸入確定
核心活動 通過向其添加新方法來組合新的物件對象和
擴展現有物件對象
撰寫更多新函式

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• 我已經在使用aync與await做開發了，沒有必要採
用其他框架來達到異部處理的需求了
• 因為牽涉到開發架構與框架，一旦採用了就沒有回
頭路了
• 因為牽涉到開發架構與框架，一旦採用了就沒有回
頭路了

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介紹 Reactive Extensions

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http://reactivex.io/

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Rx 是結合
觀察器模式, 迭代器模式與函
數編程的函式庫、框架與開
發方式。
觀察器模式, 迭代器模式與函
數編程

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RxJava
RxJS
Rx.NET
UniRx
RxScala
RxClojure
RxCpp
RxLua
Rx.rb
RxPY
RxGo
RxGroovy
RxJRuby
RxKotlin
RxSwift
RxPHP
reaxive
RxDart
RX for Xamarin(Rx.NET)
RxAndroid
RxCocoa
RxNetty

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https://github.com/Reactive-Extensions/Rx.NET
PM> Install-Package System.Reactive
或
> dotnet add package System.Reactive --version 4.0.0-preview00001

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Lab_00 - Reactive Programming Example
Talk is cheap. Show me the code !

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Rx 是結合
觀察器模式, 迭代器模式與函
數編程的函式庫、框架與開
發方式。
Rx = Observables + LINQ + Schedulers

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大话设计模式之观察者模式

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大话设计模式 - 迭代器模式之看芒果台還是央视nie？

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L IN Q

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Lab_01 – HelloWorld on Rx.NET
Talk is cheap. Show me the code!

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Rx.NET 核心觀念

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拉取(PULL)

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推播(PUSH)

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Rx.NET 主要資料結構

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IObservable<string> subject = new [] { "Jordan", "Kobe", "James"}.ToObservable();
IObservable<string> subject = Observable.FromAsync (() =>
Console.In.ReadLineAsync ());
IObservable<int> subject = Observable.Range(5, 8);
IObservable<int> subject =
from i in Observable.Range(1, 100)
from j in Observable.Range(1, 100)
from k in Observable.Range(1, 100)
where k * k == i * i + j * j
select new { a = i, b = j, c = k };
IObservable<long> subject = Observable.Timer(TimeSpan.FromSeconds(3));
Subject

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// System.Runtime.dll
public interface IObservable<T>
{
IDisposable Subscribe(IObserver<T> observer);
}
IObservable

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// System.Runtime.dll
public interface IObserver<T>
{
void OnNext(T value);
void OnCompleted();
void OnError(Exception exception);
}
IObserver

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// System.Runtime.dll
public interface IDisposable
{
void Dispose();
}
IDisposable

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// System.Reactive.Interfaces.dll
public interface IScheduler
{
DateTimeOffset Now { get; }
IDisposable Schedule<TState>(TState state, Func<IScheduler, TState,
IDisposable> action);
IDisposable Schedule<TState>(TState state, TimeSpan dueTime,
Func<IScheduler, TState, IDisposable> action);
IDisposable Schedule<TState>(TState state, DateTimeOffset dueTime,
Func<IScheduler, TState, IDisposable> action);
}
ISchedule

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Lab_02 - IObservable and IObserver with Rx.NET
Talk is cheap. Show me the code !

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Rx
Asynchronous
programming
model
Events
Delegates
Tasks
IEnumerable<T>

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Rx.NET 方法

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Rx.NET 常見操作子

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http://rxmarbles.com/

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http://rxwiki.wikidot.com/101samples

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• Lab_03 - Advance with Rx
Talk is cheap. Show me the code !

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Lab_04 - Stock Monitoring with Rx.NET
Lab_05 - MQTT with Rx.NET
Lab_06 - Xamarin with Rx.NET
Showcases

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https://reactiveui.net/

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https://github.com/Reactive-Extensions/RxJS
Draggable UI
Auto Completed
出處 ：2017 iT 邦幫忙鐵人賽 : 30 天精通 RxJS

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“Do not forget nor dwell on the past, but do forgive it. Be aware
of the future but do no fear or worry about it. Focus on the
present moment, and that moment alone.”

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常見疑問

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或是
必定
函数式反应型编程(FRP) —— 实
时互动应用开发的新思路

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ReactiveX Official Site
Intro to Rx
Interactive diagrams of Rx Observables
Cloud-Scale Event Processing with the Reactive Extensions
(Rx) - Bart De Smet
The introduction to Reactive Programming you've been
missing
A Playful Introduction to Rx by Erik Meijer

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Rx.NET in Action: With examples in C#
.NET Design Patterns
Introduction to Rx: A step by step guide to the Reactive
Extensions to .NET

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fb.com/Study4.twfb.com/groups/216312591822635 Study4.TW

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