An introduction to symfony 2 for symfony 1 developers

By Giorgio Cefaro

What is Symfony 1?

Symfony is a full-stack framework, a library of cohesive classes written in PHP.

It provides an architecture, components and tools for developers to build complex web applications faster.

from symfony-project.com

What is Symfony 2?

First, Symfony2 is a reusable set of standalone, decoupled, and cohesive PHP components that solve common web development problems.

Then, based on these components, Symfony2 is also a full-stack web framework.

I don't like MVC because that's not how the web works. Symfony2 is an HTTP framework; it is a Request/Response framework. That's the big deal. The fundamental principles of Symfony2 are centered around the HTTP specification.

from F. Potencier blog http://fabien.potencier.org/article/49/what-is-symfony2

Directory structure

Symfony 1.4

Symfony 2

General architectural differences

Symfony 1.4Full stack MVC framework

Complex controller layer

Multi-application architecture

Application/plugin level routing

Code organized in applications/modules and plugins

Symfony 2Full stack MVC decoupled components bundled in a framework, fully HTTP compliant

Simpler Controller objects

Single application

Global routing

Code organized in bundles

A bundle is like a symfony 1 plugin

Even Symfony 2 core components are distributed as bundles

Controller

Symfony 1Complex and coupled Controller Layer

Not fully replaceable (ok, let's say heavy hacking needed!)

Distributed over applications, plugins, modules, filters...

Dirty mix of routing patterns and straight module access

Symfony 2A controller can be easy as a simple PHP function

A base Controller class is supplied with several helper methods and can be used as standalone component

No routing, no party! Access to controller actions inside bundles MUST go through routing pattern matching

Configuration

Symfony 1.4Configuration Cascade

Lots of yml files (app, factories, database, security, cache, etc ) distributed through apps, plugins and modules

You can get easily lost in a complex situation

Symfony 2Configuration files inside blundles must be included manually from outside

Less configuration files

The sole config.yml is incredibly powerful

With config.yml and routing.yml you can do almost everything :-)

Handling Dependencies

Symfony 1.4Dependency handling is left to the developer

Service configuration limited to standard components

All mixed up in factories.yml

Non standard services if not properly handled may easily introduce coupling and poor testability

Symfony 2Service Container

Dependency Injection for full decoupling and high testability

Public and private services, tags, aliases

Handling Dependencies mailer example

Symfony 1.4

Symfony 2

Validation

Symfony 1.4Embedded inside forms

Validators are not easily reusable in other contexts (for example webservices)

Symfony 2Validators are sticked to Entities

Configurable via Yaml, xml, annotations or PHP

Validators are called via the Service Container

Validation

Symfony 1.4

Symfony 2

Persistence - Doctrine

Symfony 1.4Bundled with the framework as a standard (with Propel as an alternative)

Active Record

Design requires lot of effort to make code fully testable

Symfony 2Totally decoupled from the framework via Service Container

Entities are independent from OR[D]M

Entities are mapped to DB via metadata definition (Yaml, xml, or annotations)

Persistence - Doctrine

Symfony 1.4

schema.yml

Symfony 2

Product.orm.yml

Persistence - Doctrine

Symfony 1

Symfony 2

Cache

Symfony 1.4Non-standard cache mechanism, though flexible and configurable

Symfony 2Standard RFC 2616 HTTP Cache

Testing

Symfony 1.4Lime framework bundled as a standard, PHPUnit can be used as a plugin

Lime is not as powerful as PHPUnit

Symfony 2Fully integrated with PHPUnit framework

In functional tests internal objects can be fully inspected (kernel and DI container too!)

Should I move to Symfony 2?

Yes.

Giorgio Cefaro

Twitter: @giorrrgiolinkedin.com/in/giorgiocefaro