Chapter 6. PHP Streams API and Higher-Order Observables

In this chapter, we'll introduce a lot of new features that we need for the next chapter. Almost everything covered in this chapter is related to PHP Streams API, Promises and event loops (reactphp/event-loop project in our case). This also includes a couple of more advanced RxPHP operators working with so-called higher-order Observables.

In particular, in this chapter, we'll do the following:

• Quickly look at using Promises in PHP with the reactphp/promise library
• Introduce PHP Streams API and, with examples, see what benefits it brings with minimal or no effort
• Examine the internals of StreamSelectLoop class, this time in the context of PHP Streams API
• See what caveats we need to be aware of when working with non-blocking code in event loops
• Talk about higher-order Observables
• Introduce four new and more advanced operators, concatAll(), mergeAll(), combineLatest() and switchMap(), which are...