connect-style middleware handling in php.

satellite.php

<?php
namespace satellite;

class Request {
	
	public $method;
	
	public $url;
	
	public $headers;
	
	public function __construct($method, $url, $headers) {
		
		$this->method = $method;
		$this->url = $url;
		$this->headers = $headers;
		
	}
	
}

class Response {
	
	public function writeHead($status_code, $headers) {
		
	}
	
	public function write($chunk) {
		
	}
	
	public function end($data) {
		
	}
	
}

class Middleware {
	
	public $request;
	
	public $response;
	
	public $chain = array();
	
	public function __construct() {
		
		$this->request = new Request(
			$_SERVER['REQUEST_METHOD'],
			$_SERVER['REQUEST_URI'],
			$this->get_headers());
			
		$this->response = new Response();
		
		$this->chain = func_get_args();
		
	}
	
	public function add($middleware) {
		
		array_push($this->chain, $middleware);
		
	}
	
	public function run($i = 0) {
		
		$self = $this;
		
		if ($m = $this->chain[$i]) {
			$middleware = new $m();
			$middleware($this->request, $this->response, function() use ($self, $i) {
				$self->run($i + 1);
			});
		}
		
	}
	
	private function get_headers() {

		if(function_exists('apache_request_headers')) {
		    return apache_request_headers();
		}

		// http://www.electrictoolbox.com/php-get-headers-sent-from-browser/
		$headers = array();
		foreach($_SERVER as $key => $val) {
			if(substr($key, 0, 5) == 'HTTP_') {
				$headers[str_replace(' ', '-', ucwords(str_replace('_', ' ', strtolower(substr($key, 5)))))] = $val;
			}
		}

		return $headers;

	}
	
}

usage.php

<?php
require "satellite.php";

class Love {
  public function __invoke($req, $res, $next) {
    echo 'I love ';
    $next();	
  }
}

class Lamb {
  public function __invoke($req, $res, $next) {
    echo 'my lambs';
    $next();	
  }	
}

// will print "I love my lambs"
$m = new satellite\Middleware(Love, Lamb);
$m->run();