This document summarizes a talk about using Domain-Driven Design patterns and principles when developing applications with the Symfony framework. It discusses where to store business logic in an MVC application, avoiding anemic domain models by putting logic in entities. It provides examples of domain models, repositories, value objects, and strategies when building a Symfony application with DDD in mind. Finally, it outlines common DDD patterns and principles and recommends resources for further reading on the topic.

1. DDD on example of Symfony
Oleg ZInchenko
1cdecoder@gmail.com

2. cystbear
Symfony expert
MongoDB adept
Erlang fun
OSS doer
KNPer
https://twitter.com/1cdecoder
https://github.com/cystbear
http://knplabs.com/

3. What this talk about?

4. About useful tool/lib?

5. About success story?

6. No! It’s about idea
Motivation!

7. MVC

8. Where to store business logic?
Model
View
Controller

9. Where to store business logic?
Model
View
Controller

10. Where to store business logic?
Model
View
Controller

11. Where to store business logic?
Model
View
Controller -- YEAH!

12. Welcome to
Fat Stupid Ugly Controllers
FSUC/FUC
http://blog.astrumfutura.com/2008/12/the-m-in-mvc-why-models-are-misunderstood-and-unappreciated/
http://zendframework.ru/anonses/model-with-mvc
http://habrahabr.ru/post/175465/

13. Anemic (Domain) Model
“In essence the problem with anemic domain
models is that they incur all of the costs of a domain
model, without yielding any of the benefits.”
Martin Fowler
http://www.martinfowler.com/bliki/AnemicDomainModel.html
http://habrahabr.ru/post/224879/

14. Model
Persistence Layer

16. What is
Not MVC (phew!)
Request / Response Framework
HTTP Framework
http://fabien.potencier.org/article/49/what-is-symfony2

17. What about model,
persistence layer?

18. Meet Doctrine
http://www.doctrine-project.org/
SQL -- DBAL + ORM
MongoDB
CouchDB
OrientDB
PHPCR ODM
OXM

19. http://www.martinfowler.com/articles/injection.html
http://fabien.potencier.org/article/11/what-is-dependency-injection
http://fabien.potencier.org/article/13/introduction-to-the-symfony-service-container

20. Services
http://groovy.codehaus.org/
https://grails.org/
Single Class
With its Deps (min) set
Easy to Replace
Easy to Test
MVC(S)!

21. Controller’s pray
https://twitter.com/ornicar
Get Request
Submit form if any
Call one Service method
Return Response
Rendering HTML far away

22. Managers Managers Managers
http://blog.codinghorror.com/i-shall-call-it-somethingmanager/
http://stackoverflow.com/questions/1866794/naming-classes-how-to-avoid-
calling-everything-a-whatevermanager
<SmtManager>
<WhatEverManager>
<MyManager>
<EtcManager>

23. Real Pain
class BackendUserProgramsPossessionFormHandler
{
protected $dep1; // deps holder props
public function __construct(DepsClass $dep1 /*, ...*/)
{
$this->dep1 = $dep1;
}
public function process(Form $form)
{
$this->dep1->makeHappy($form);
// ...
}

24. How Kris writes Symfony apps#44
https://twitter.com/kriswallsmith
http://www.slideshare.net/kriswallsmith/how-kris-writessymfonyapps

25. How Kris writes Symfony apps#44
https://twitter.com/kriswallsmith
http://www.slideshare.net/kriswallsmith/how-kris-writessymfonyapps

26. Just A Thought
https://twitter.com/mr_r_miller/status/522343384900718592

27. Domain Logic Patterns
http://martinfowler.com/books/eaa.html

28. Domain Logic Patterns
http://martinfowler.com/books/eaa.html
Transaction Script
Domain Model
Table Module
Service Layer

29. Transaction Script

30. Domain Model

31. Table Module

32. Domain Logic
&
Application logic

33. Service Layer

35. What is next?
RAD
DDD Patterns
Examples
Layers
Goodies

36. DDD != RAD
Code First
Do not Care about persistence (yet)

37. Patterns & Code
Domain Model
Repository
Value Object
DTO
Strategy
State

38. Domain Model

39. Domain Model
<?php
namespace MegaCorpCoreProduct;
class Product
{
private $id;
private $name;
private $recognitionStrategy;
public function __construct(
ProductId $id, $name, $recognitionStrategy
) {
$this->id = $id;
$this->name = $name;
$this->recognitionStrategy = $recognitionStrategy;
}

40. Repository
<?php
namespace MegaCorpCoreProduct;
interface ProductRepository
{
public function find(ProductId $productId);
public function findAll();
public function add(Product $product);
public function remove(Product $product);
}

41. Value Object
<?php
namespace MegaCorpCore;
class ProductId
{
private $value;
public function __construct($value)
{
$this->value = (string) $value;
}
public function getValue()
{
return $this->value;
}
}

42. Value Object DateRange

43. Value Object DateRange
<?php
public function findByDateRange(
DateTime $from, DateTime $to )
class DateRange
{
private $from;
private $to;
public function __construct(DateTime $from, DateTime $to)
{
$this->from = $from;
$this->to = $to;
}
}
public function findByDateRange(DateRange $range)

44. Value Object Money

45. <?php
class Money
{
private $amount;
private $currency;
public function __construct(
$amount,
Currency $currency
) {
// ...
}
}
Value Object Money

46. <?php
class ProfileData
{
public $firstName;
public $lastName;
public $birthday;
}
DTO

47. Strategy

48. ______ ______ _______ _______
/ | / __ | | ____|
| ,----'| | | | | .--. || |__
| | | | | | | | | || __|
| `----.| `--' | | '--' || |____
______| ______/ |_______/ |_______|

49. src
└── MegaCorp
Directory structure
├── ApiBundle
│ ├── Controller
│ │ └── ...
│ └── MegaCorpApiBundle.php
├── Core
│ └── Product
│ ├── Product.php
│ ├── ProductId.php
│ └── ProductRepository.php
└── CoreBundle
├── Controller
│ └── ...
├── Repository
│ ├── InMemoryProductRepository.php
│ └── MongoDbProductRepository.php
└── MegaCorpCoreBundle.php

50. Layers

51. Layers
Domain Layer -- heart of your application, Entities and Repositories
Application Layer -- Controllers
Presentation Layer -- Templates / DTOs for serializer
Infrastructure Layer -- framework, persistence, concrete
implementations of Domain Layer

52. Useful goodies

53. BBB DDD by Eric Evans
http://amzn.com/0321125215/

54. DDD Quickly by InfoQ
http://www.infoq.com/minibooks/domain-driven-design-quickly

55. PoEAA by Martin Fowler
http://amzn.com/B008OHVDFM/

56. DDD and Patterns by Jimmy Nilsson
http://amzn.com/B0054KOKQQ/

57. Links
http://dddcommunity.org/
http://williamdurand.fr/
http://welcometothebundle.com/
http://verraes.net/
http://jimmynilsson.com/blog/
http://www.martinfowler.com/
http://elephantintheroom.io/ -- podcast
http://msdn.microsoft.com/en-us/magazine/dd419654.aspx
http://www.martinfowler.com/bliki/AnemicDomainModel.html
http://martinfowler.com/bliki/CQRS.html

59. Thanks!