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PHP Reactive Programming

By : Sikora

2 (1)

PHP Reactive Programming

2 (1)

By: Sikora

Overview of this book

Reactive Programming helps us write code that is concise, clear, and readable. Combining the power of reactive programming and PHP, one of the most widely used languages, will enable you to create web applications more pragmatically. PHP Reactive Programming will teach you the benefits of reactive programming via real-world examples with a hands-on approach. You will create multiple projects showing RxPHP in action alone and in combination with other libraries. The book starts with a brief introduction to reactive programming, clearly explaining the importance of building reactive applications. You will use the RxPHP library, built a reddit CLI using it, and also re-implement the Symfony3 Event Dispatcher with RxPHP. You will learn how to test your RxPHP code by writing unit tests. Moving on to more interesting aspects, you will implement a web socket backend by developing a browser game. You will learn to implement quite complex reactive systems while avoiding pitfalls such as circular dependencies by moving the RxJS logic from the frontend to the backend. The book will then focus on writing extendable RxPHP code by developing a code testing tool and also cover Using RxPHP on both the server and client side of the application. With a concluding chapter on reactive programming practices in other languages, this book will serve as a complete guide for you to start writing reactive applications in PHP.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Introduction to Reactive Programming

1. Introduction to Reactive Programming

Imperative programming

Declarative programming

Sequential and parallel programming

Asynchronous programming

Functional programming

Reactive programming

Reactive Extensions

Introducing RxPHP

Summary

2. Reactive Programming with RxPHP

2. Reactive Programming with RxPHP

Basic principles of Reactive Extensions

Naming conventions in Reactive Extensions

Components of RxPHP

Writing the DebugSubject class

Writing JSONDecodeOperator

Writing CURLObservable

The proc_open() and non-blocking fread()

Event loop and RxPHP

Summary

3. Writing a Reddit Reader with RxPHP

3. Writing a Reddit Reader with RxPHP

Examining RxPHP's internals

Observable::create() and Observable::defer()

Writing a Reddit reader using RxPHP

Non-blocking CURLObservable

Types of disposable classes

Summary

4. Reactive versus a Typical Event-Driven Approach

4. Reactive versus a Typical Event-Driven Approach

Handling error states in operator chains

The concat() and merge() operators

Writing a reactive event dispatcher

Summary

5. Testing RxPHP Code

5. Testing RxPHP Code

The doOn*() operators

Installing the PHPUnit package

Basics of writing tests using PHPUnit

Testing RxPHP code

Testing SumOperator

Testing ForkJoinObservable

Summary

6. PHP Streams API and Higher-Order Observables

6. PHP Streams API and Higher-Order Observables

Using Promises in PHP

PHP Streams API

Higher-order Observables

Summary

7. Implementing Socket IPC and WebSocket Server/Client

7. Implementing Socket IPC and WebSocket Server/Client

Backpressure in Reactive Extensions

Implementing ProcessObservable

Server Manager application

Server Manager and the Unix socket server

Implementing a WebSocket server

Implementing a WebSocket client

Summary

8. Multicasting in RxPHP and PHP7 pthreads Extension

8. Multicasting in RxPHP and PHP7 pthreads Extension

Subjects

Multicasting in RxPHP

PHP pthreads extension

RxPHP and pthreads

Summary

9. Multithreaded and Distributed Computing with pthreads and Gearman

9. Multithreaded and Distributed Computing with pthreads and Gearman

Introduction to the PHP Parser library

Implementing ThreadPoolOperator

Introduction to Gearman

Summary

10. Using Advanced Operators and Techniques in RxPHP

10. Using Advanced Operators and Techniques in RxPHP

The zip() operator

The window() operator

The materialize() and dematerialize() operators

Error handling in RxPHP operator chains

The Observable::create() method versus the Subject class

Call stack length and EventLoopScheduler

Unsubscribing versus completing an Observable

Anonymous operators

Writing a custom DirectoryIteratorObservable

FTP client with RxPHP

Summary

Appendix. Reusing RxPHP Techniques in RxJS

Appendix. Reusing RxPHP Techniques in RxJS

What is RxJS?

A quick introduction to RxJS 5 in Node.js

Higher-order Observables in RxJS 5 and RxPHP

Operators specific for RxJS 5

Summary

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Handling error states in operator chains

If we go back to Chapter 2 , Reactive Programming with RxPHP, and CURLObservable, we know that it emits onError when it wasn't able to download any data. The question is, what if we want to try downloading the URL again? And even more interestingly, repeat the failed attempt every few seconds.

Subscribing only to onError signals is simple with the second parameter to the subscribeCallback() method:

(new CURLObservable('https://example.com')) 
    ->subscribeCallback(null, function($e) { ... });

It's obvious that nesting another CURLObservable into onError handler is probably not an option. This is exactly what the retry() operator is designed for.

The retry() operator

When the retry() operator receives an onError signal, it captures it and tries to resubscribe to its source Observable. It takes as an argument the number of times it tries to resubscribe until it passes the error signal down the operator chain.

Let's rewrite the preceding...

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