Developing a PSR-7 Request class

One of the key characteristics of PSR-7 middleware is the use of Request and Response classes. When applied, this enables different blocks of software to perform together without sharing any specific knowledge between them. In this context, a request class should encompass all aspects of the original user request, including such items as browser settings, the original URL requested, parameters passed, and so forth.

How to do it...

1. First, be sure to define classes to represent the Uri, Stream, and UploadedFile value objects, as described in the previous recipe.
2. Now we are ready to define the core Application\MiddleWare\Message class. This class consumes Stream and Uri and implements Psr\Http\Message\MessageInterface. We first define properties for the key value objects, including those representing the message body (that is, a StreamInterface instance), version, and HTTP headers:

   namespace Application\MiddleWare;
   use Psr\Http\Message\ { 
     MessageInterface, ...