Creating your own framework on top of Symfony2 Components

Creating your own framework using
Symfony2 Components

Contents
• Symfony Introduction
• Going OOP with the HttpFoundation Component
• Front controller Pattern
• Routing Component
• HttpKernel Component : The Controller Resolver
• EventDispatcher Component
• HttpKernel Component : TheHttpKernel class
• Dependency-Injection Component
• Technical facts about Symfony
• Final code of our framework
• Resources

Symfony Introduction
Symfony is a reusable set of standalone, decoupled and cohesive PHP components
that solve common web development problems.
Symfony Components
• HttpFoundation
• Routing
• HttpKernel
• Debug
• EventDispatcher
• DependencyInjection
• Security
• Validator
• Yaml
.
Fun to Install !!
{
"require": {
"symfony/http-foundation": "^3.0”,
"symfony/routing": "^3.0",
"symfony/http-kernel": "^3.0",
"symfony/debug": "^3.0“,
"symfony/event-dispatcher": "^3.0“,
"symfony/dependency-injection": "^3.0",
"symfony/yaml": "^3.0",
}
}composer install;
<?php
require_once __DIR__.'/../vendor/autoload.php';

Going OOP with the HttpFoundation Component
$_GET
$_POST
$_COOKIE
$_SESSION
$_FILES
Request
Response
Cookie
Session
UploadedFile
RedirectResponse
documentation

$input = isset($_GET['name']) ? $_GET['name'] : 'World';
header('Content-Type: text/html; charset=utf-8');
printf('Hello %s', htmlspecialchars($input, ENT_QUOTES, 'UTF-8'));
Starting with our framwork
// simplex/index.php
require_once __DIR__.'/vendor/autoload.php';
use SymfonyComponentHttpFoundationRequest;
use SymfonyComponentHttpFoundationResponse;
$request = Request::createFromGlobals();
$input = $request->get('name', 'World');
$response = new Response(sprintf('Hello %s', htmlspecialchars($input, ENT_QUOTES, 'UTF-8')));
$response->send();
$ composer require symfony/http-foundation

Lets see code snippet after HttpFoundation (pt1)

Utilising “Front Controller” design pattern
• src/ : source code for our app (not publiciy accessible)
vendor/ : any third-party Libraries
web/ : use to house anything that needs to be accessible from the web server,
including assets & out front controller

Lets see code snippet after implementing FrontController
(pt2)

Mapping URLs with Routing Component
Routing component documentation
Basic parts of routing system
• RouteCollection – contains the route definitions (instances of class Route)
• RequestContext - contains information about Request
• UrlMatcher – performs the mapping of the Request to a single Route
$ composer require symfony/routing

New version of our framework using Routing Component
// simplex/web/index.php
require_once __DIR__.'/vendor/autoload.php';
$request = Request::createFromGlobals();
$routes = include __DIR__.'/../src/routes.php';
$context = new RoutingRequestContext();
$context->fromRequest($request);
$matcher = new RoutingMatcherUrlMatcher($routes, $context);
try {
extract($matcher->match($request->getPathInfo()), EXTR_SKIP);
ob_start();
include sprintf(__DIR__.'/../src/pages/%s.php', $_route);
$response = new Response(ob_get_clean());
} catch (RoutingExceptionResourceNotFoundException $e) {
$response = new Response('Not Found', 404);
} catch (Exception $e) {
$response = new Response('An error occurred', 500);
}
$response->send();
// example.com/src/routes.php
use SymfonyComponentRouting;
$routes = new RoutingRouteCollection();
$routes->add('hello', new RoutingRoute('/hello
array('name' => 'World')));
$routes->add('bye', new RoutingRoute('/bye'))
return $routes;

Lets see code snippet after implementing
RoutingComponent (pt3)

Introducing Controllers in Routing Component
// simplex/src/routes.php
$routes->add('hello', new RoutingRoute('/hello/{name}', array(
'name' => 'World',
'_controller' => function ($request) {
// $foo will be available in the template
$request->attributes->set('foo', 'bar');
$response = render_template($request);
// change some header
$response->headers->set('Content-Type', 'text/plain');
return $response;
}
)));
// simplex/web/index.php
try {
$request->attributes->add($matcher->match($request->getPathInfo()));
} catch (RoutingExceptionResourceNotFoundException $e) {
$response = new Response('Not Found', 404);
} catch (Exception $e) {
$response = new Response('An error occurred', 500);
}
$response = call_user_func($request->attributes->get('_controller'), request);
'_controller' => function ($request) {
// $foo will be available in the template
$request->attributes->set('foo', 'bar');
$response = render_template($request);
// change some header
$response->headers->set('Content-Type','text/plain');
return $response;
}

Lets see code snippet after implementing Controller in
RoutingComponent (pt4)

Introducing Controllers in Routing Component (continued)

$ composer require symfony/http-kernel
A non-desirable side-effect , noticed it ??

HttpKernel Component : The Controller Resolver
Using Controller Resolver
public function indexAction(Request $request)
// won't work
public function indexAction($request)
// will inject request and year attribute from request
public function indexAction(Request $request, $year)

Integrating Controller Resolver in our framework

Lets see code snippet after implementing
ControllerResolver (pt5)
This completes part 1 of series
Projects using Symfony2 components

Downsides in our framework code
• We need to copy front.php each time we create a new website.
It would be nice if we could wrap this code into a proper class

Separation of concerns (MVC) continued..

Updating routes.php

Lets see code snippet (part - 6)

Our application has now Four Different layers :
1. web/front.php: The front controller, initializes our application
2. src/Simplex: The reusable framework class
3. src/Calendar: Application specific code (controllers & models)
4. src/routes.php: application specific route configurations

EventDispatcher Component
documentation

On Response Listener
Registering Listener and dispatching event from front controller
Moved listener code into its own class

Lets see code snippet (part - 7)

Using Subscribers instead of Listeners
Registering subscriber
Creating Subscriber

The HttpKernel component
Code implementation part 8

Creating your own framework on top of Symfony2 Components

Resources
Resources:
▸ Symfony2 official page https://symfony.com/
▸ Symfony Book
▸ Symfony2 Components
▸ Knp University
▸ Create Framework using Symfony2 components blog
▸ BeIntent Project code structure

Creating your own framework on top of Symfony2 Components

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