PSR-7 was a great step in the PHP community, but it is only halfway to the goal that could free PHP coders from monolithic MVC frameworks and allow them to compose agnostic PHP apps out of a range of reusable middlewares. It only defines HTTP messages (the request and the response); it never defines how to deal with them afterward. So, we need a request handler to process the request in order to produce a response.
Like PSR-7, PSR-15 is a set of common interfaces, but they take things a step further and specify the standard for request handlers (HTTP server request handlers) and middleware (HTTP server request middleware). It was accepted on 22 January 2018. We will cover the HTTP server request middleware in the next section. Now, let's understand the HTTP server request handlers in the PSR-15 interface, RequestHandlerInterface:
// Psr\Http\Server\RequestHandlerInterface
namespace Psr\Http\Server;
use Psr...
