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.
Table of Contents (18 chapters)
PHP Reactive Programming
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Unsubscribing versus completing an Observable


We know that when we have an observer we'll stop receiving items when the source Observable completes or when we manually unsubscribe. However, we haven't talked about why we might choose one over the other.

There're basically two ways to stop receiving items:

  • Unsubscribe from the source Observable

  • Using an operator that completes the chain (such as the takeUntil() operator)

By unsubscribing we usually mean that we don't want to be receiving items any more. This obviously doesn't mean that the source Observable stopped sending items or sent the complete notification. We're just no longer interested in the items coming from the source.

As an important consequence to manually unsubscribing, the complete handler is never called. Consider the following example where we unsubscribe after receiving a few items:

// unsubscribe_01.php 
$loop = new StreamSelectLoop(); 
$scheduler = new EventLoopScheduler($loop); 
 
$subscription = Observable...