Reactive programming in PHP
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This document provides an introduction and overview of reactive programming in PHP using RxPHP. It discusses key concepts like the observer pattern, streams, operators like map and filter, and subjects. It provides examples of subscribing observers to observables, using operators like interval and flatMap, and subjects. It notes pros like handling asynchronous events but also cons like difficulty understanding and overhead. In summary, it serves as a high-level introduction to reactive programming principles and how they can be applied in PHP projects using the RxPHP library.
![RxPHP
$source = RxObservable ::fromArray([1, 2, 3, 4]);
$observer = new RxObserverCallbackObserver(
function ($x) {
echo 'Next: ', $x, PHP_EOL;
},
function (Exception $ex) {
echo 'Error: ', $ex ->getMessage(), PHP_EOL;
},
function () {
echo 'Completed', PHP_EOL;
});
$source ->subscribe($observer);
// Next: 1
// Next: 2
// Next: 3
// Next: 4
// Completed
Very simple sample code
• Cold Observable Sample, almost
useless
• Source = Observable
• Subscribe Observer to
Observable
• Observer is consist of three
functions
• next, error, completed](https://image.slidesharecdn.com/reactiveprogramming-180704020048/85/Reactive-programming-in-PHP-11-320.jpg)
Reactive programming in PHP
- 1. Reactive Programming in PHP Johney Park 2018.06.17
- 2. Reactive Programming = Observer Pattern + LINQ-style operators ( + Schedulers) TL; DR
- 3. Pros: Good for handling async events Cons: Difficult to understand Too many things to learn Some overhead TL; DR
- 4. Definition Reactive Programming is programming with asynchronous data streams. https://gist.github.com/ staltz/868e7e9bc2a7b8c1f754 (Where is reactive?)
- 5. What you heard when you learn reactive programming • Observer/Observable / Hot & Cold • Signal / Flux / Stream / EventStream / EventSource / … • Subject • Scheduler • Publish / Subscribe / Unsubscribe / Dispose / Behavior • Producer / Consumer • Map / Reduce / Throttle / …
- 6. Observer Pattern Observer 1 Observable watch & run Observer 2 ♨ (Event Source) wrap
- 7. Observer Pattern Observer 1 Observable subscribe Lazy Evaluation Subscription 1 async call with stream operators Observer 2 Subscription 2 Observers don’t observe Observable does all the work Producer / Consumer may be better naming
- 8. Observer Pattern Observer 1 Observable 1 Observer 2 Observer 3 Subject 1 Subject 2 Subject = Observable + Observer broadcast ♨ (Event Source) ♨ (Event Source) direct call
- 9. When to use RP? • One or more event sources • Require stream operators • Not a perfect solution for all async scenarios • External API Call (MSA) • UI Events (Click) • Message Processing • Abstraction over Async Process
- 10. RxPHP • stream_select (PHP 4 >= 4.3.0, PHP 5, PHP 7) • ReactPHP != RxPHP • ReactPHP is event-driven, non-blocking I/O library • EventLoop, Promise from ReactPHP • https://github.com/ReactiveX/RxPHP
- 11. RxPHP $source = RxObservable ::fromArray([1, 2, 3, 4]); $observer = new RxObserverCallbackObserver( function ($x) { echo 'Next: ', $x, PHP_EOL; }, function (Exception $ex) { echo 'Error: ', $ex ->getMessage(), PHP_EOL; }, function () { echo 'Completed', PHP_EOL; }); $source ->subscribe($observer); // Next: 1 // Next: 2 // Next: 3 // Next: 4 // Completed Very simple sample code • Cold Observable Sample, almost useless • Source = Observable • Subscribe Observer to Observable • Observer is consist of three functions • next, error, completed
- 12. RxPHP $loop = Factory ::create(); Scheduler ::setDefaultFactory(function () use ($loop) { return new SchedulerEventLoopScheduler($loop); }); register_shutdown_function(function () use ($loop) { $loop ->run(); }); Observable ::interval(1000) ->take(5) ->flatMap(function ($i) { return Observable ::of($i + 1); }) ->subscribe(function ($e) { echo $e, PHP_EOL; }); // 1 // 2 // 3 // 4 // 5 Event Loop • We need to set EventLoop when using stream operator • interval, throttle, etc.. • If you don’t use stream operator, you don’t need to set EventLoop • RxJs don’t require explicit event loop, because Javascript has setTimeout, setInterval, requestAnimationFrame • There are many scheduler types • flatMap == mergeMap, but RxPHP don’t provide mergeMap
- 13. RxPHP $subject = new RxSubjectSubject(); $subject ->subscribe(function($i) { echo $i . PHP_EOL;}); RxObservable ::interval(1000) ->take(5) ->flatMap(function ($i) { return Observable ::of($i + 1); }) ->subscribe($subject); $subject ->onNext(10); $subject ->onNext(20); $subject ->onNext(30); // 10 // 20 // 30 // 1 // 2 // 3 // 4 // 5 Subject • Subject = Observable + Observer • Actually Subject is extended from Observable • You don’t need to create custom Observable for simple usage
- 14. RxPHP More Samples • https://github.com/ReactiveX/RxPHP/tree/master/demo • https://github.com/PacktPublishing/PHP-Reactive- Programming/ • https://www.packtpub.com/web-development/php- reactive-programming
- 15. RxPHP Ben Lesh’s comment RxJS could be so simple... just a handful of types and operators. ... but if we do that, then people shoot themselves in the foot with memory leaks and their own poorly implemented `expand` operator or whatever… ... so then we add 60+ operators and people are like "WHOA...." haha.. Now it's too complicated. It's tough everywhere. Haha If I had a nickel for every poorly implemented custom RxJS operator I've seen… ... I'd only have about 25 cents, because we've already built almost every tool someone could want. But who have we scared off in the process?
- 16. The End