2015 Middleware exists in a mature form in many languages, including Java, Ruby, Python, or Node. PHP is also warming up to this idea. This presentation focuses on HTTP middleware, HttpKernelInterface interface and implementations.

1. the rise of
middleware
PHP Frameworks
Emmanuel Idé

2. PHP Frameworks
Phase I
Decouple!
OO / MVC

3. PHP Frameworks
Phase II
Decouple!!
IoC / Dependency Injection

4. PHP Frameworks
Phase III
Decouple!!!
MiddleWare

5. What is middlewarehttps://mattstauffer.co/blog/laravel-5.0-middleware-filter-style
The way this works is that middleware
implements a decorator pattern: it takes the
request, does something, and returns another
request object to the next layer of the stack.

6. What is middlewarehttp://stackoverflow.com/questions/2256569/what-is-rack-middleware
Middleware is a dreadful term which refers to
any software component/library which assists
with but is not directly involved in the execution
of some task.

7. Decorator Pattern
Attach additional responsibilities
to an object dynamically, without
using subclassing.

8. Pipes-and-Filters Pattern
The Pipes and Filters architectural
pattern provides a structure for
systems, having components that
process a stream of data (filters) and
connections that transmit data
between adjacent components (pipes).

9. HTP Interfaces
1997: Java Servlet
2003: Python WSGI
2007: Ruby Rack
2010: Node Express
2011: Symfony2 HttpKernelInterface

10. HTP Interfaces
1997: Java Servlet
2003: Python WSGI
2007: Ruby Rack
2010: Node Express
2011: Symfony2 HttpKernelInterface

11. Rack definitions
Environment
Environment variables representing the HTTP request. Mostly taken
from CGI, but has additional Rack-specific variables.
Response
The response format. It is an array with three elements: The status
code, a hash of headers and a list of strings for the body.
Application
An app is an object with a call method. The input argument is an env
hash, the return value a response array.

12. Ruby
class HelloWorld
def call(env)
[200, {"Content-Type" => "text/plain"}, ["Hello world!"]]
end
end
class HelloWorld def call(env) [200, {"Content-Type" => "text/plain"}, ["Hello world!"]] end end

13. Why shall we care,
we have SAPI
$_SERVER, $_ENV, $_GET, $_POST, $_COOKIE, $_FILES and
$_REQUEST

14. stackphp.com
Stack is a convention for composing HttpKernelInterface middlewares.

15. Symfony 2
HttpKernelInterface
- No specification
- coupled to the framework

16. Symfony 3
the HttpKernel is going to be
split into several smaller ones

17. Who supports stack?
Laravel, Symfony, Drupal, etc..
(ZF3 roadmap announces alternative to stack)