There are many Symfony versions around, and it's good to know the differences between them to learn how the framework was evolving during these years. The first stable Symfony version — 1.0 — was released in the beginning of 2007 and was supported for three years. In mid-2008, version 1.1 was presented, which wasn't compatible with the previous release, and it was difficult to upgrade any old project to this.

Symfony 1.2 version was released shortly after this, at the end of 2008. Migrating between these versions was much easier, and there were no dramatic changes in the structure. The final versions of Symfony 1's legacy family was released nearly one year later. Simultaneously, there were two version releases, 1.3 and 1.4. Both were identical, but Symfony 1.4 did not have deprecated features, and it was recommended to start new projects with it. Version 1.4 had 3 years of support.

If you look into the code, version 1.x was very different from version 2. The company that was behind Symfony (the French company, SensioLabs) made a bold move and decided to rewrite the whole framework from scratch.

The first release of Symfony2 wasn't perfect, but it was very promising. It relied on Git submodules (the composer did not exist back then). The 2.1 and 2.2 versions were closer to the one we use now, although it required a lot of effort to migrate to the upper level. Finally, the Symfony 2.3 was released — the first long-term support version within the 2.x branch. After this version, the changes provided within the next major versions (2.4, 2.5, and 2.6) are not so drastic and usually they do not break compatibility.

Prior to installing Symfony2, you don't need to have a configured web server. If you have at least PHP version 5.4, you can use the standalone server provided by Symfony2. This server is suitable for development purposes and should not be used for production. It is strongly recommend to work with a Linux/UNIX system for both development and production deployment of Symfony2 framework applications. While it is possible to install and operate on a Windows box, due to its different nature, working with Windows can sometimes force you to maintain a separate fragment of code for this system.

To install Symfony2, you can use a few methods as follows:

To install Symfony2 through an installer, go to the Symfony website at http://symfony.com/download, and install the Symfony2 installer by issuing the following commands:

$ sudo curl -LsS http://symfony.com/installer -o /usr/local/bin/symfony
$ sudo chmod +x /usr/local/bin/symfony

After this, you can install Symfony by just typing the following command:

$ symfony new <new_project_folder>

To install the Symfony2 framework for a to-do application, execute the following command:

$ symfony new todoapp

This command installs the latest Symfony2 stable version on the newly created todoapp folder, creates the Symfony2 application, and prepares some basic structure for you to work with.

After the app creation, you can verify that your local PHP is properly configured for Symfony2 by typing the following command:

$ php app/check.php

If everything goes fine, the script should complete with the following message:

[OK]
Your system is ready to run Symfony projects

Symfony2 is equipped with a standalone server. It makes development easier. If you want to run this, type the following command:

$ php app/console server:run

If everything went alright, you will see a message that your server is working on the IP 127.0.0.1 and port 8000. If there is an error, make sure you are not running anything else that is listening on port 8000. It is also possible to run the server on a different port or IP, if you have such a requirement, by adding the address and port as a parameter, that is:

$ php app/console server:run 127.0.0.1:8080

If everything works, you can now type the following:

http://127.0.0.1:8000/

Now, you will visit Symfony's welcome page.

This page presents you with a nice welcome information and useful documentation link.

Let's dive in to the initial directory structure within the typical Symfony application. Here it is:

While Symfony2 is very flexible in terms of directory structure, it is recommended to keep the basic structure mentioned earlier.

The following table describes their purpose:

So, in most cases, you will be usually modifying and creating the PHP files within the src/ directory, the view and configuration files within the app/ directory, and the JS/CSS files within the web/ directory.

The main directory also holds a few files as follows:

The .gitignore file's purpose is to provide some preconfigured settings for the Git repository, while the composer.json and composer.lock files are the files used by the composer dependency manager.

$ curl -sS https://getcomposer.org/installer | php

$ curl -sS https://getcomposer.org/installer | php
$ sudo mv composer.phar /usr/local/bin/composer

$ php composer.phar require friendsofsymfony/user-bundle ^1.3
Using version ^1.3 for friendsofsymfony/user-bundle
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing friendsofsymfony/user-bundle (v1.3.6)
    Loading from cache

friendsofsymfony/user-bundle suggests installing willdurand/propel-typehintable-behavior (Needed when using the propel implementation)
Writing lock file
Generating autoload files
...

{
"name": "wbancer/todoapp",
"license": "proprietary",
"type": "project",
"autoload": {
  "psr-0": {
    "": "src/",
    "SymfonyStandard": "app/SymfonyStandard/"
  }
},
"require": {
  "php": ">=5.3.9",
  "symfony/symfony": "2.7.*",
  "doctrine/orm": "~2.2,>=2.2.3,<2.5",
  // [...]
  "incenteev/composer-parameter-handler": "~2.0",
  "friendsofsymfony/user-bundle": "^1.3"
},
"require-dev": {
  "sensio/generator-bundle": "~2.3"
},
"scripts": {
  "post-root-package-install": [
  "SymfonyStandard\\Composer::hookRootPackageInstall"
  ],
  "post-install-cmd": [
  // post installation steps
  ],
  "post-update-cmd": [
  // post update steps
  ]
},
"config": {
  "bin-dir": "bin"
},
"extra": {
  // [...]
}
}

Each application has a need to hold some global and machine-specific parameters and configurations. Symfony2 holds configuration within the app/config directory and it is split into a few files as follows:

All the files except the parameters.yml* files contain global configuration, while the parameters.yml file holds machine-specific information such as database host, database name, user, password, and SMTP configuration.

The default configuration file generated by the new Symfony command will be similar to the following one.

This file is auto-generated during the composer install:

parameters:
    database_driver: pdo_mysql
    database_host: 127.0.0.1
    database_port: null
    database_name: symfony
    database_user: root
    database_password: null
    mailer_transport: smtp
    mailer_host: 127.0.0.1
    mailer_user: null
    mailer_password: null
    secret: 93b0eebeffd9e229701f74597e10f8ecf4d94d7f

As you can see, it mostly holds the parameters related to database, SMTP, locale settings, and secret key that are used internally by Symfony2. Here, you can add your custom parameters using the same syntax. It is a good practice to keep machine-specific data such as passwords, tokens, api-keys, and access keys within this file only. Putting passwords in the general config.yml file is considered as a security risk bug.

The global configuration file (config.yml) is split into a few other files called routing*.yml that contain information about routing on the development and production configuration. The file called as security.yml holds information related to authentication and securing the application access. Note that some files contains information for development, production, or test mode. You can define your mode when you run Symfony through the command-line console and when you run it through the web server. In most cases, while developing you will be using the dev mode.

To finish this chapter, let's take a look at the Symfony console script. We used it before to fire up the development server, but it offers more. Execute the following:

$ php app/console

You will see a list of supported commands. Each command has a short description. Each of the standard commands come with help, so I will not be describing each of them here, but it is worth to mention a few commonly used ones:

You can, of course, write your own Symfony2 commands and we will do this within the forthcoming chapters.

In this chapter, we have demonstrated how to use the Symfony2 installer, test the configuration, run the deployment server, and play around with the Symfony2 command line. We have also installed the composer and learned how to install a package using it.

While we haven't written much code in this chapter, information contained here will be used in all the other chapters. To demonstrate how Symfony2 enables you to make web applications faster, we will try to learn through examples that can be found in real life. To make this task easier, we will try to produce a real to-do web application with modern look and a few working features.

In the next chapter, we will review the default bundle structure, and set up the first routings, controllers, and templates. We will also create some initial database schema and models, and we will present migration and fixtures system.