PHP Middleware: A Journey to the Center of The App

Middleware is a term to describe the layers wrapped around your application logic. With the adoption of PSR-15, PHP's common interfaces for handling HTTP requests and middleware components, you can now easily add community-developed Middleware modules to your app or framework or create your own.

What you will learn:

-What is Middleware?
-The journey your HTTP request makes to the center of your application logic
-Why it's useful to encapsulate pieces of your application logic using middleware.

Transcript

1. PHP Middleware
2. Hello My name is Sarah @sarahescarroll
3. Agenda • What middleware is • Why use middleware • How to implement middleware • Resources • Cute elephant photos
4. Middle What?
5. First, some terminology
6. PHP Framework Interop Group (PHP-FIG)
7. PSR (PHP Standards Recommendation) A collection of specifications and interfaces published by the PHP-FIG.
8. PSR-7 The specification and interfaces for HTTP messages.
9. PSR-15 The specification and interfaces for HTTP request handlers and middleware components.
10. Ok, so what is middleware?
11. There are a lot of definitions online...
13. Wikipedia “Middleware is computer software that provides services to software applications beyond those available from the operating system. It can be described as ‘software glue’.”
14. Red Hat “Middleware is multipurpose software that provides services to applications outside of what’s offered by the operating system. Any software between the kernel and user apps can be middleware.”
15. Microsoft “Middleware is software that lies between an operating system and the applications running on it. Essentially functioning as hidden translation layer, middleware enables communication and data management for distributed applications.”
17. “...it seems that mostly all 'wares' are in the middle of something. So, are all things middleware?” - Random Stack Overflow User
19. PHP Middleworld “In the realm of web application development Middleware refers to functions wrapped around business logic. They rely upon the decorator pattern and are composed in a sort of layered stack. You could think of them as onion layers...”
20. My summary... • Logic wrapped around the core of your application • Allows you to manipulate the request and/or response • Like an onion
21. Diagram from StackPHP website: https://stackphp.com/
22. Or like the layers of the earth? or
23. Diagram from random Science for Kids website: https://www.ducksters.com/science/composition_of_the_earth.php
25. Common Use Cases for Middleware Session handling Logging Security & authentication Dev & debugging Routing Setting response headers
26. Frameworks and Client Libraries • Symfony • Laravel • Zend Expressive • Slim • Guzzle
27. Why?
28. Why is middleware useful? • Encapsulation • Reusability • Decoupling • Testing • Community Standards
29. How?
30. How to write a middleware component? Following the PSR-15 specification • Must implement MiddlewareInterface • May create and return a response if conditions aren’t met • Or delegate to the provided handler
37. How are all the middleware layers connected? Delegate to the request handler
38. How to write a request handler? Also following the PSR-15 specification • Must implement RequestHandlerInterface • May create and return a response • Or call the next middleware in the stack
39. How to write a request handler? The Awesome PSR-15 list has open source dispatcher examples. Example inspired by lightweight implementation: https://github.com/equip/dispatch/blob/master/src/Handler.php
49. Connecting it together & defining the stack?
55. Resources
56. PSR-7 spec: https://www.php-fig.org/psr/psr-7/ PSR-15 spec: https://www.php-fig.org/psr/psr-15/ PHP Middleworld: https://www.php-middleworld.com/ Awesome PSR-15 List of Open Source Middleware: https://github.com/middlewares/awesome-psr15-middlewares Links!
57. Thank you
58. Bonus Elephant Fact Their brains can weigh up to 12 pounds and are the largest brain of all animals living on land.