Osiąganie mądrej architektury z Symfony2

Achieving wise architecture
with Symfony2

Wojciech Sznapka
ALEJE.IT

Wojciech Sznapka
Technical Manager @ XSolve
Zend Certified Engineer since 2010
Symfony Framework since 2008
PHP since 2004
Web development since 2001

Besides: ice hockey, windsurfing, skiing, crime stories

How can
architecture
be bad?

Classes with
hundreds
lines of code?

Model mixed with
View located in
Controler ?

Changes and
maintanance
costing fortune ?

Crashing due to
enormous load ?

Unable to migrate
to cloud ?

Make it
wisely
with Symfony2

Most popular
framework in
PHP ecosystem

2078 Forks
6245 Favs
1910 Bundles

Built on top of
best patterns

So... is
Symfony2
a silver bullet?

Symfony2 is only
good tool ...

… but even good tools
can be used poorly

So let's keep in mind
three good rules...

S ingle responsibility principle
O pen/closed principle
L iskov substitution principle
I nterface segregation principle
D ependency inversion principle

Each service should have
exactly one
purpose

Other responsibilities
should be
aggregated in services
injected as dependencies

<?php

namespace WowoNewsletterBundleNewsletterModel;

class MailingManager implements MailingManagerInterface
{
protected $templateManager;

public function __construct(TemplateManagerInterface $templateManager)
{
$this->templateManager = $templateManager;
}

public function createMailing($data, Mailing $mailing)
{
$body = $this->templateManager->applyTemplate($mailing->getBody(), $mailing->getTitle());
$mailing->setBody($body);
$mailing->setSubject($data['subject']);

return $mailing;
}
}

Services should be
closed for modification
But opened for extension

Abstract classes
helps with
Open/Closed principle

<?php

abstract class Animal
{
public function makeHappySound()
{
return sprintf("Happilly %sn", $this->speak());
}

abstract public function speak();
}

class Dog extends Animal
{
function speak()
{
return "Woof, woof!";
}
}

class Cat extends Animal
{
function speak()
{
return "Meow...";
}
}

foreach (array(new Dog, new Cat) as $creature) {
printf($creature->makeHappySound());
}

It should be possible to
replace class with other
implementation

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
http://symfony.com/schema/dic/services/services-1.0.xsd">

<parameters>
<parameter
key="mailing_manager.class">WowoNewsletterBundleNewsletterModelMailingManager</parameter>
</parameters>

<services>
<service id="wowo_newsletter.mailing_manager" class="%mailing_manager.class%">
<argument type="service" id="wowo_newsletter.entity_manager" />
<argument>%wowo_newsletter.model.contact.class%</argument>
<call method="setTemplateManager">
<argument type="service" id="wowo_newsletter.template_manager"/>
</call>
</service>
</services>
</container>

#config_dev.yml

parameters:
mailing_manager.class: WowoNewsletterBundleMocksMailingManagerFancyMock

Interfaces should be
fine grained

Many specific interfaces
Are better than one
generalpurpose

<?php

interface PlaceholderProcessorInterface
{
public function process($object, $body);
}

interface TemplateManagerInterface
{
public function setAvailableTemplates(array $templates);
public function getAvailableTemplates();
public function applyTemplate($body, $title);
}

interface MediaManagerInterface
{
public function embed($body, Swift_Message $message);
public function getRegex($name);
}

interface BuilderInterface
{
public function buildMessage($mailingId, $contactId, $contactClass);
}

interface SenderInterface
{
public function send($mailingId, $contactId, $contactClass);
}

Application should be
decoupled into
dependant upon
abstractions modules

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://symfony.com/schema/dic/services
http://symfony.com/schema/dic/services/services-1.0.xsd">

<services>
<service id="twig.extension.acme.demo"
class="AcmeDemoBundleTwigExtensionDemoExtension" public="false">
<tag name="twig.extension" />
<argument type="service" id="twig.loader" />
</service>

<service id="acme.demo.listener" class="AcmeDemoBundleEventListenerControllerListener">
<tag name="kernel.event_listener" event="kernel.controller"
method="onKernelController" />
<argument type="service" id="twig.extension.acme.demo" />
</service>
</services>
</container>

Live application needs
to be tested

logging

<?php

class MailingPersistService implements PersistService, LoggerAware
{
// [...]

protected $logger;

public function setLogger(Logger $logger)
{
$this->logger = $logger;
}

public function Mailing(EntityMailing $mailing)
{
$user = $this->security->getUser();
try {
$this->entityManager->persist($mailing);
$this->logger->info(sprintf('Mailing #%d %s has been saved by %s',
$mailing->getId(), $mailing, $user),
array('mailing' => $mailing, 'user' => $user));
} catch (Exception $e) {
$this->logger->err(sprintf('Problem while saving mailing by user %s: %s',
$user, $e->getMessage()),
array('exception' => $e, 'user' => $user));
}
}

monitoring

Keep sessions in
global storage
like database or NoSQL

Store user files
global storage
like S3 or MongoFS

Write logs to
central logger
like syslogd or logstash

Scale your DB with
master/slave connections
using Doctrine

Wise
architecture
ingridients

Design based on
SOLID principles

Problems solved with
existing bundles
made by community

Code covered with
automatic tests

Wojciech Sznapka
wojciech@sznapka.pl
blog.sznapka.pl
@sznapka
@wowo

Osiąganie mądrej architektury z Symfony2

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