Book Image

PHP Reactive Programming

By : Martin Sikora
Book Image

PHP Reactive Programming

By: Martin 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.

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Table of Contents (18 chapters)
PHP Reactive Programming
PHP Reactive Programming
Credits
Credits
About the Author
About the Author
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Customer Feedback
Customer Feedback
Preface
Preface
Free Chapter
1
Introduction to Reactive Programming
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
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
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
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
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
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
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
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
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
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
11
Reusing RxPHP Techniques in RxJS
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

Non-blocking CURLObservable

In our Reddit reader app, we download data from a remote API using PHP's cURL. Even when using its asynchronous callbacks, such as CURLOPT_PROGRESSFUNCTION, it's important to keep in mind that curl_exec() is still a blocking call, no matter what options we choose.

This is due to the fact that PHP runs in a single execution thread and when it starts executing curl_exec(), everything else needs to wait until it finishes. It's true that this method might call some callback functions, but if any of them got stuck, for example, in an infinite loop, the curl_exec() function would never end.

This has serious implications for the actual responsiveness of our Reddit reader. While CURLObservable is downloading data, it doesn't respond to any user input, which is probably not what we want.

When we talked about IntervalObservable and how it's able to keep the desired interval very precisely, we didn't mention that this is, in fact, a type of situation it can't handle.

Let's make...

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