Symfony2 - from the trenches

Symfony2 - From the Trenches

by Lukas Kahwe Smith,
Kris Wallsmith,
Thibault Duplessis,
Jeremy Mikola,
Jordi Boggiano,
Jonathan H. Wage,
Bulat Shakirzyanov

Agenda

Getting Setup Caching
Code Flow Performance Tips
Dependency Injection Asset Management
Configuration Choices Testing
Controller Choices Deployment
Application Choices Third Party Bundles
Doctrine Resources

Getting setup
PHP 5.3+ with ext/intl (compat lib is in the works)
Read check.php for details (dev/prod php.ini's from Liip)
Using OSX?
php53-intl from liangzhenjing or build-entropy-php from chregu
Blog post on installing PHP 5.3 with intl from Justin Hileman
Initial setup
symfony-sandbox
symfony-bootstrap
Symfony2Project

Read the Coding Style Guide (Code Sniffer Rules)

Managing external dependencies

Submodule: not everything is in git (svn, mercurial, etc.)
Vendor install/update scripts: risk of getting out of sync
MR (not cross platform)

Code Flow
1. Frontend Controller (web/app[_dev].php)
Loads autoloader
Creates/boots kernel
Creates request (from globals) and passes to kernel
2. Kernel
Loads app config (app/config/config_[prod|dev|test])
Resolves URL path to a controller (go to 3)
Outputs response returned by the controller
3. Controller
Loads model and view
Potentially creates a sub-request (go to 2)
Creates response and returns it

<?xml version="1.0" encoding="utf-8" ?>
<container xmlns="http://www.symfony-project.org/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<parameters>
<parameter key="sitemap.class">BundleAvalancheSitemapBundleSitemap</parameter>
</parameters>

<services>
<service id="sitemap" class="%sitemap.class%" />
</services>

</container>

Describe Your Services

<?php
class cachedDevDebugProjectContainer extends Container
{
/**
* Gets the 'sitemap' service.
*
* @return BundleAvalancheSitemapBundleSitemap
*/
protected function getSitemapService()
{
return $this->services['sitemap'] = new BundleAvalancheSitemapBundleSitemap();
}

/**
* Gets the default parameters.
*
* @return array An array of the default parameters
*/
protected function getDefaultParameters()
{
return array(
'sitemap.class' => 'BundleAvalancheSitemapBundleSitemap'
);
}
}

Service Definitions Are Dumped to Raw PHP

Service Container (aka DIC)

Benefits:
No performance loss
Lazy instantiation
Readable service configurations

Gotchas:
Can become hard to work with if the DI extension tries to do
too much
Be aware of circular dependencies
Might lead to code that cannot be used outside of DIC

<?php
class SomeClass
{
private $container;

public function __construct(ContainerInterface $container) <service id="some_service" class="SomeClass">
{ <argument type="service" id="service_container" />
$this->container = $container; </service>
} 
// or <service id="some_service" class="SomeClass">
public function setContainer(ContainerInterface $container) <call method="setContainer">
{ <argument type="service" id="service_container" />
$this->container = $container; </call>
} </service>

public function getDocumentManager()
{
return $this->container->get('document_manager');
}
}

Container Injection

<?php
class SomeClass
{
private $documentManager;

public function __construct(DocumentManager $documentManager)
{
$this->documentManager = $documentManager;
}

{
return $this->documentManager;
}
}

<service id="some_service" class="SomeClass">
<argument type="service" id="document_manager" />
</service>

Constructor Injection

<?php
class SomeClass
{

public function setDocumentManager(DocumentManager $documentManager)
{
}

{
}
}

<service id="some_service" class="SomeClass">
<call method="setDocumentManager">
</call>
</service>

Setter Injection

<?php
interface SomeInterface
{
function setDocumentManager(DocumentManager $documentManager);
}

class SomeClass implements SomeInterface
{

public function setDocumentManager(DocumentManager $documentManager)
{
}

{
}
}

<interface id="some_service" class="SomeInterface">
<call method="setDocumentManager">
</call>
</interface>

<service id="some_service" class="SomeClass" />

Interface Injection

Configuration Choices

Symfony supports XML, YAML and PHP for configuration
YAML and PHP uses underscore to separate words
XML uses dashes to separate words
XML attributes usually map to array values in
YAML/PHP
YAML merge key syntax to reuse pieces within a file
XSD-aware editors provide auto-completion/validation
XML is recommended for Bundle/DI configuration
YAML is recommended for application configuration
Bundle extensions can optionally utilize the Config
component to normalize/parse configurations in any format
See FrameworkExtension, SecurityExtension, TwigExtension

Controller Choices

Defining Controllers as services is optional
Non-service controllers must use container injection
Create a Bundle extension to load Bundle services

It's recommended to not extend from the base Controller
The base controller is mainly a tool for beginners
It provides convenience methods that invoke services,
such as generateUrl(), redirect(), render()

Application Choices

Security system makes it possible to have just one
application for both frontend and admin backend
Location of AppKernel is totally flexible, just update the
frontend controllers accordingly
Large projects should use multiple applications
Better separation when multiple teams work
Facilitate step-by-step updating and refactoring
For example: main, mobile, API, admin

Doctrine Examples

Retrieve references to entity/document without DB queries
Using raw SQL queries with Doctrine2 ORM
Simple search engine with Doctrine MongoDB ODM

Retrieving References w/o DB Queries

$tags = array('baseball', 'basketball');
foreach ($tags as $tag) {
$product->addTag($em->getReference('Tag', $tag));
}

Raw SQL Queries

$rsm = new ResultSetMapping;
$rsm->addEntityResult('User', 'u');
$rsm->addFieldResult('u', 'id', 'id');
$rsm->addFieldResult('u', 'name', 'name');

$query = $this->_em->createNativeQuery('SELECT id, name
FROM users WHERE name = ?', $rsm);
$query->setParameter(1, 'romanb');

$users = $query->getResult();
http://www.doctrine-project.org/docs/orm/2.0/en/reference/native-sql.html

Simple Search Engine

interface HasKeywords
{
function setKeywords();
function getKeywords();
}

/** @mongodb:EmbeddedDocument */
class Keyword
{
// ...

/** @mongodb:String @mongodb:Index */
private $keyword;

/** @mongodb:Integer */
private $score;

// ...
}

/** @mongodb:Document */
class Product implements HasKeywords
{
/** @mongodb:Id */
private $id;

/** @mongodb:String */
private $title;

/** @mongodb:EmbedMany(targetDocument="Keyword") */
private $keywords = array();

// ...
}

class KeywordListener
{
public function preUpdate(PreUpdateEventArgs $eventArgs)
{
$entity = $eventArgs->getEntity();
if ($entity instanceof HasKeywords) {
$entity->setKeywords($this->buildKeywords($entity));
}
}

private function buildKeywords(HasKeywords $entity)
{
$keywords = array();
// build keywords from title, description, etc.
return $keywords;
}
}


// find products by keyword
$products = $dm->createQueryBuilder()
->field('keywords.keyword')->all($keywords)
->getQuery()
->execute();

Doctrine in the Real World

Go see Jon Wage's talk at later today!

Database Migrations

Deploy DB schema changes before the code
Prevent DB schema BC breaks
Use DoctrineMigrationBundle
app/console doctrine:migrations:diff
app/console doctrine:migrations:migrate
Do not use entities in migration scripts ever!
Write fixtures as migrations or make the fixtures able to
update existing data gracefully
app/console doctrine:data:load --fixtures=app/fixtures

Different Content Areas of a Page

Caching with Edge Side Includes

Symfony2 provides support for Edge Side Includes (ESI)
Proxy assembles page from snippets of HTML
Snippets can have different cache rules
Develop without ESI, test with Symfony2 internal ESI
proxy, deploy using ultra-fast Varnish Proxy
Break up page into different controller actions based on
cache invalidation rules
Do not worry about overhead from multiple render calls
Never mix content that has different cache timeouts
Consider caching user specific content in the client
Varnish Reverse Proxy
Super fast, PHP cannot match its performance
Cache full pages for anonymous users
Not just for HTML, also useful for JSON/XML API's

Page Rendered Behind a Reverse Proxy

Asset Management

Go see Kris Wallsmith's talk next!

Performance Tips

Dump routes to Apache rewrite rules
app/console router:dump-apache
Write custom cache warmers
Do not explicitly inject optional services to controllers
If your controller receives many services, which are
optional or unused by some actions, that's probably a
hint that you should break it up into multiple controllers
Do minimal work in the controller, let templates pull
additional data as needed
Use a bytecode cache with MapFileClassLoader

Testing
Symfony2 rocks for unit and functional testing
Dependency Injection, core classes have interfaces (easy mocking)
No base classes, no static dependencies, no ActiveRecord
Client fakes "real" requests for functional testing (BrowserKit
component)
Functional Testing
Pros: tests configuration, tests API not implementation
Unit Testing
Pros: pinpoints issues, very directed testing
http://www.slideshare.net/avalanche123/clean-code-5609451
Recommendation:
Functional testing is recommended for controller actions
Symfony2 provides WebTestCase and BrowserKit
Unit testing for complex algorithms, third party API's too hard
to mock
Use LiipFunctionalTesting to load fixtures, validate HTML5

Deployment

Debian style (aka Liip Debian Packager)
Write a manifest in YAML
Build Debian packages with MAKE
Install with apt-get install
Server specific settings are asked during install, change later with
dpkg-reconfigure
Maintain a global overview of all application dependencies in case of
(security) updates
Watch Lukas' unconference talk later today!

Fabric (used at OpenSky)
Repository managed with git-flow
Clone tagged release branch, init submodules
Fix permissions (e.g. cache, log), delete dev/test controllers
Replace password/API-key placeholders with prod values in config
files
Upload in parallel to production nodes, swap "current" symlink

Third Party Bundles

@weaverryan
Ryan Weaver

Here's a new year's resolution: to *always*
work on an existing Symfony2 bundle and
never recreate my own. #focus #teamwork

27 Dec http://twitter.com/weaverryan/status/19565706752299009

Third Party Bundles
Many vendors have already published bundles:

FriendsOfSymfony (http://github.com/friendsofsymfony)
UserBundle (forked from knplabs' DoctrineUserBundle)
FacebookBundle (forked from kriswallsmith)
Liip (http://github.com/liip)
FunctionalTestBundle
ViewBundle
OpenSky (http://github.com/opensky)
LdapBundle
Sonata (http://github.com/sonata-project)
AdminBundle

Additionally, a couple sites currently index community bundles:

http://symfony2bundles.org/
http://symfohub.com/

Third Party Bundles

Bundles should follow the best practices
No version-tagging or official package manager (yet)
Use bundles by adding git submodules to your project
Maintain your own fork and "own" what you use
Not all bundles are equally maintained
Symfony2 API changes => broken bundles
If you track symfony/symfony, learn to migrate bundles
Avoid rewriting a bundle's services/parameters directly
The bundle's DI extension should allow for such
configuration; if not, submit a pull request
If absolutely necessary, a CompilerPass is cleaner

Contributing to Third Party Bundles

Similar to Symfony2's own patch guidlines
Fork and add remote repository
Merge regularly to keep up-to-date
Avoid committing directly to your master
Merges from upstream should be fast-forwards
Once upstream changes are stable, bump your
project's submodule pointer


Create branches for patches and new features
Can't wait to use this in your project? Temporarily
change your project submodule to point to your
branch until your pull request is accepted.
Help ensure that your pull request merges cleanly
Create feature branch based on upstream's master
Rebase or merge upstream's master when finished


Was your pull request accepted? Congratulations!
Don't merge your feature branch into master!
Doing so would cause your master to divert
Merge upstream's master into your master
Delete your feature branch
Update your project's submodule to point to master

Resources

If you want to jump in and contribute:
http://docs.symfony-reloaded.org/master/contributing/community/other.
html
If you are still fuzzy on Dependency Injection:
http://fabien.potencier.org/article/11/what-is-dependency-injection
If you keep up with Symfony2 repository on github:
http://docs.symfony-reloaded.org/master/

Application Using Dependency Injection

Dependency Injection

All objects are instantiated in one of two ways:
Using the "new" operator
Using an object factory
All objects get collaborators in one of two ways
Passed to object constructor
Set using a setter

Symfony2 - from the trenches

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