1.
Surgeon General's Warning
This talk is clocked at 1 slide per 12.8 seconds and features unsafe
amounts of code. Presenter is a registered Class 3 Fast Talker (equal
to 1 Gilmore Girls episode).
Viewing is not recommended for those hungover, expected to become
hungover or consuming excessive amounts of caffeine. Do not watch
and operate motor vehicles.
If you accidentally consume this talk, flush brain with kitten pictures
and seek emergency help in another talk. No hard feelings, seriously.
It's almost the end of the conference, after all. Why are we even here?
Notice in accordance with the PHP Disarmament Compact of 1992. Void where prohibited.

2.
Models & Service Layers
Hemoglobin & Hobgoblins
ZendCon 2014
Ross Tuck

3.
Freerange Codemonkey
Know-It-All
Hot-Air Balloon

4.
@rosstuck
rosstuck.com

5.
About Today

6.
Hemoglobin

7.
Anemia.

8.
Objects can too.

9.
Model
class TodoList {
function setName($name);
function getName();
function setStatus($status);
function getStatus();
function addTask($task);
function setTasks($tasks);
function getTasks();
}

10.
array(
'name' => '',
'status' => '',
'tasks' => ''
);
Model

11.
Bad ThingTM

12.
“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

13.
Our industry standard i s a n a n t i p a t t ern.

14.
Ouch.

15.
Important Note

16.
Models
Stuf

17.
Integration over implementation

18.
Our Setup

19.
Model
class TodoList {
function setName($name);
function getName();
function setStatus($status);
function getStatus();
function addTask($task);
function setTasks($tasks);
function getTasks();
}

20.
Model
class Task {
function setDescription($desc);
function getDescription();
function setPriority($priority);
function getPriority();
}

21.
An ORM that's not Doctrine 2.
A framework that's not Symfony2.
I promise.

22.
CRUD

23.
Controller
function addTaskAction($req) {
$task = new Task();
$task->setDescription($req->get('desc'));
$task->setPriority($req->get('priority'));
$list = $this->todoRepo->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
return $this->redirect('edit_page');
}

24.
Controller
function addTaskAction($req) {
$task = new Task();
$task->setDescription($req->get('desc'));
$task->setPriority($req->get('priority'));
$list = $this->todoRepo->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
return $this->redirect('edit_page');
}

25.
Anemic Model
Hard to Maintain
Testability
SRP wha?

26.
In Defense Of CRUD.
No, seriously.

27.
Low Barrier to Entry.

28.
Easy to follow.
If you can keep it
in your head.

29.
Sometimes it really is just data entry.
(but it usually isn't)
(but sometimes it is)

30.
Not entirely a technical issue.

31.
Service Layer

32.
• Service Layer
• Service Container
• Web Service
• Service Oriented Architecture
• Domain Service
• Stateless Service
• Software-as-a-service
• Platform-as-a-service
• Whatever-as-a-service meme
• Delivery Service
• Laundry Service

33.
Application Service

34.
Model
Controller
View

35.
Model
Service Layer
Controller
View

36.
Why?

37.
1) Multiple User Interfaces
Web + REST API
+ CLI
+ Workers

38.
2) “In between” Logic

39.
3) Decouple from frameworks

40.
Model
Service Layer
Controller
View

41.
Just Build The Stupid Thing

42.
Service
Layer

43.
Controller
function addTaskAction($req) {
$task = new Task();
$task->setDescription($req->get('desc'));
$task->setPriority($req->get('priority'));
$list = $this->todoRepo->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
return $this->redirect('edit_page');
}

44.
Service
class TodoService {
function addTask(TodoList $list, $desc, $priority) {
$task = new Task();
$task->setDescription($desc);
$task->setPriority($priority);
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

45.
Service
class TodoService {
function findById($id) {
return $this->repository->findById($id);
}
}

46.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
}

47.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($id, $desc, $priority) {
$list = $this->todoService->findById($id);
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask($list, $desc, $priority);

48.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
function addTaskCommand($id, $desc, $priority) {
$list = $this->todoService->findById($id);
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask($list, $desc, $priority);
CLI

49.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($id, $desc, $priority) {
$list = $this->todoService->findById($id);
if (!$list) { throw new NotFoundException(); }
$this->todoService->addTask($list, $desc, $priority);

50.
Service
class TodoService {
function findById($id) {
return $this->repository->findById($id);
}
}

51.
Service
class TodoService {
function findById($id) {
$todo = $this->repository->findById($id);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}
not http exception

52.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($id, $desc, $priority) {
$list = $this->todoService->findById($id);
$this->todoService->addTask($list, $desc, $priority);

53.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($id, $desc, $priority) {
$list = $this->todoService->findById($id);
$this->todoService->addTask($list, $desc, $priority);

54.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($name, $desc, $priority) {
$list = $this->todoService->findByName($name);
$this->todoService->addTask($list, $desc, $priority);

55.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($name, $desc, $priority) {
$list = $this->todoService->findByName($name);
$this->todoService->addTask($list, $desc, $priority);

56.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($name, $desc, $priority) {
$list = $this->todoService->findByName($name);
$this->todoService->addTask($list, $desc, $priority);

57.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
CLI
function addTaskCommand($name, $desc, $priority) {
$listId = $this->todoService->findIdByName($name);
$this->todoService->addTask($listId, $desc, $priority);

58.
Service
class TodoService {
public function findLatestLists() {
return $this->repository->findLatestLists();
}
}

59.
Service
class TodoService {
public function findLatestLists() {
if ($this->cache->has('latest:lists')) {
return $this->cache->get('latest:lists');
}
$results = $this->repository->findLatestLists();
$this->cache->set('latest:lists', $results);
return $results;
}
}

60.
Indirect Advantages

61.
Readability

62.
Interface Protection

63.
Discoverability

64.
Service
class TodoService {
function findById($id);
function addTask($todo, $desc, $priority);
function prance();
}

65.
Mission Accomplished

66.
Model
class TodoList {
function setName($name);
function getName();
function setStatus($status);
function getStatus();
function setTasks($tasks);
function getTasks();
}

67.
Dumb as a box of rocks.

68.
Model
class TodoList {
function setName($name);
function getName();
function setStatus($status);
function getStatus();
function setTasks($tasks);
function getTasks();
}
Where's mah logic?

69.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$task = new Task();
$task->setDescription($desc);
$task->setPriority($priority);
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

70.
“Organizes business logic by procedures
where each procedure handles a single
request from the presentation.”
-Fowler

71.
Transaction Scripts

72.
Simple

73.
More flexible
Than CRUD,
at least

74.
Don't scale quite as well

75.
What does belong in a service layer?

76.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$task = new Task();
$task->setDescription($desc);
$task->setPriority($priority);
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

77.
Orchestration

78.
Transactions
Security
Notifications
Bulk operations

79.
Facade

80.
Fat Model, Skinny Controller

81.
Fat Model, Skinny Service Layer

82.
(re)Thinking

83.
addTask()
findById()
findLatestLists()
Service
write
read
read

84.
Remodeling our Reading
by
Refactoring our Repository
Redux

85.
Service
class TodoService {
function findById($id) {
$todo = $this->repository->findById($id);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}

86.
Repository
interface TodoRepository {
public function findById($id);
public function findLatestLists();
}

87.
Repository
class TodoDbRepository implements TodoRepository {
public function findById($id) {
$todo = $this->db->select(...);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}

88.
Repository
class TodoDbRepository implements TodoRepository {
public function findById($id) {
$todo = $this->db->select(...);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}
raw db connection

89.
Repository
class TodoDbRepository implements TodoRepository {
public function findById($id) {
$todo = $this->repository->find($id);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}
FIXED

90.
Repository
interface TodoRepository {
public function findById($id);
public function findLatestLists();
}

91.
Repository
interface EntityRepository {
public function createQueryBuilder($alias);
public function createResultSetMappingBuilder($alias);
public function createNamedQuery($queryName);
public function createNativeNamedQuery($queryName);
public function clear();
public function find($id, $lockMode, $lockVersion);
public function findAll();
public function findBy($criteria, $orderBy, $limit, $offset);
public function findOneBy($criteria, $orderBy);
public function __call($method, $arguments);
public function getClassName();
public function matching(Criteria $criteria);
}

92.
Repository
interface TodoRepository {
public function findById($id);
public function findLatestLists();
}

93.
Service
class TodoService {
function findById($id) {
$todo = $this->repository->findById($id);
if (!$todo) {
throw new TodoNotFoundException();
}
return $todo;
}
}

94.
Service
class TodoService {
function findById($id) {
return $this->repository->findById($id);
}
}

95.
Service
class TodoService {
public function findLatestLists() {
if ($this->cache->has('latest:lists')) {
return $this->cache->get('latest:lists');
}
$results = $this->repository->findLatestLists();
$this->cache->set('latest:lists', $results);
return $results;
}
}

96.
Repository
class TodoDbRepository implements TodoRepository {
public function findLatestLists() {
if ($this->cache->has('latest:lists')) {
return $this->cache->get('latest:lists');
}
$results = $this->repository->query(...);
$this->cache->set('latest:lists', $results);
return $results;
}
}

97.
Repository Decorator Decorator object
class CachingTodoRepository implements TodoRepository {
public function findLatestLists() {
if ($this->cache->has('latest:lists')) {
return $this->cache->get('latest:lists');
}
$results = $this->innerRepository->findLatestLists();
$this->cache->set('latest:lists', $results);
return $results;
}
}
TodoDbRepository

98.
DI Layer
new TodoService(
new CachingTodoRepository(
new TodoDbRepository(
$entityManager->getRepository('TodoList')
)
)
)

99.
The Inverse Biggie Law

100.
Mo' classes
Mo' decoupling and reduced overall design issues

101.
Too many finder methods?

102.
Controller
$this->todoService->matching(array(
new ListIsClosedCriteria(),
new HighPriorityCriteria()
));

103.
DoctrineCriteria

104.
Interlude: Services here...
...services there...
...services everywhere!

105.
TaskService
Task
TodoListService
TodoList
TagService
Tag
TaskRepository TodoListRepository TagRepository

106.
TaskService
Task
TodoListService
TodoList
TagService
Tag
TaskRepository TodoListRepository TagRepository

107.
Task
TodoService
TodoList
Tag

108.
Task
UserService
TodoService
TodoList
Tag
User

109.
Task
TodoService
TodoList
Tag
UserService
User

110.
Service
class TodoListService {
public function findByUser(User $user) {
return $this->repository->findByUser($user);
}
}

111.
Service
class TodoListService {
public function findByUser(UserId $userId) {
return $this->repository->findByUser($userId);
}
}

112.
Task
TodoService
TodoList
Tag
Interfaces!
UserService
User

113.
Services aren't only for entities

114.
Scale can differ wildly

115.
PrintingService

116.
Quality of Implementation

117.
(re)Modeling our Writing

118.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$task = new Task();
$task->setDescription($desc);
$task->setPriority($priority);
$task->setTodoList($list);
$this->repository->save($task);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

119.
Model
class TodoList {
function addTask(Task $task) {
$this->tasks[] = $task;
}
}

120.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task();
$task->setDescription($desc);
$task->setPriority($priority);
$this->tasks[] = $task;
}
}

121.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority);
$this->tasks[] = $task;
}
}

122.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
}
}
ORM allowance

123.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority);
$this->tasks[] = $task;
}
}

124.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

125.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority);
$this->tasks[] = $task;
}
}

126.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority);
$this->tasks[] = $task;
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}
}

127.
Meaningful Tests

128.
Working Together

129.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

130.
Model
class TodoList {
function addTask($desc, $priority) {
$task = new Task($desc, $priority);
$this->tasks[] = $task;
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}
}

131.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

132.
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
if (count($this->tasks) > 10) {
$this->auditLog->logTooAmbitious($task);
$this->mailer->sendMessage('Too unrealistic');
}
Service

133.
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
if (count($this->tasks) > 10) {
$this->auditLog->logTooAmbitious($task);
$this->mailer->sendMessage('Too unrealistic');
}
Service

134.
TodoService
PrintingService

135.
Something new...

136.
Something better...

137.
Domain Events

138.
Common Pattern

139.
Observer

140.
New usage

141.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}

142.
Event
class TaskAddedEvent {
protected $description;
protected $priority;
function __construct($desc, $priority) {
$this->description = $desc;
$this->priority = $priority;
}
}

143.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}

144.
Model
class TodoList {
protected $pendingEvents = array();
protected function raise($event) {
$this->pendingEvents[] = $event;
}
public function releaseEvents() {
$events = $this->pendingEvents;
$this->pendingEvents = array();
return $events;
}
}
Excellent Trait

145.
No dispatcher

146.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$this->auditLog->logNewTask($task);
$this->mailer->sendMessage('New thingy!');
}
}

147.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
}
}

148.
Service
class TodoListService {
function addTask(TodoList $list, $desc, $priority) {
$list->addTask($desc, $priority);
$this->repository->save($list);
$events = $list->releaseEvents();
$this->eventDispatcher->dispatch($events);
}
}

149.
Event Listeners
class EmailListener {
function onTaskAdded($event) {
$taskDesc = $event->getDescription();
$this->mailer->sendMessage('New thingy: '.$taskDesc);
}
function onUserRegistered($event) {
$this->mailer->sendMessage('welcome sucka!');
}
}

150.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}

151.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
$this->raise(new WasTooAmbitiousEvent($this->id));
}
}

152.
Nice things:

153.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
$this->raise(new WasTooAmbitiousEvent($this->id));
}
}
Logic is here!

154.
Service
class TodoListService {
protected $dependency1;
protected $dependency2;
protected $dependency3;
protected $dependency4;
protected $dependency5;
protected $dependency6;
}
Big ball of mud
in the making

155.
Event Listeners
class EmailListener {
function onTaskAdded($event) {
$taskName = $event->task->getName();
$this->mailer->sendMessage('New thingy: '.$taskName);
}
function onUserRegistered($event) {
$this->mailer->sendMessage('welcome sucka!');
}
}
Thin. Easy to test

156.
TodoService
Serialize & Send,
Sucka!
PrintingService

157.
Model
function addTask($desc, $priority) {
$task = new Task($desc, $priority, $this);
$this->tasks[] = $task;
$this->raise(
new TaskAddedEvent($this->id, $desc, $priority)
);
if (count($this->tasks) > 10) {
$this->status = static::UNREALISTIC;
}
}

158.
Less nice things.

159.
Humans hate debugging events.
Dev Logging.
Debug commands.

160.
Model
Service Layer
Controller
View

161.
Model
Service Layer
Controller
View

162.
Model
Service Layer
Controller
View

163.
Consuming Application Services

164.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
}

165.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$this->todoService->addTask(
$list, $req->get('desc'), $req->get('priority')
);
return $this->redirect('edit_page');
}

166.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$list->addTask($req->get('desc'), $req->get('priority'));
return $this->redirect('edit_page');
}

167.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$list->addTask($req->get('desc'), $req->get('priority'));
$list->rename('blah');
return $this->redirect('edit_page');
}

168.
Controller
function addTaskAction($req) {
$list = $this->todoService->findById($req->get('id'));
$list->addTask($req->get('desc'), $req->get('priority'));
$list->rename('blah');
$this->todoService->addTask(...);
return $this->redirect('edit_page');
}

169.
Model
Service Layer
Controller
View

170.
Model
Service Layer
Controller
View

171.
Model
Service Layer
Controller
View

172.
View Models

173.
PHP version, not MVVM.

174.
Service
class TodoService {
function findById($id) {
$todoList = $this->repository->findById($id);
return $todoList;
}
}

175.
Service
class TodoService {
function findById($id) {
$todoList = $this->repository->findById($id);
return new TodoDTO($todoList);
}
}

176.
TodoDTO
class TodoDTO {
public function getName();
public function getStatus();
public function getMostRecentTask();
}

177.
Service
class TodoService {
function generateReport() {
$data = $this->repository->performSomeCrazyQuery();
return new AnnualGoalReport($data);
}
}

178.
Ain't rocket science.

179.
Reverse it: DTOs not for output...

180.
...but for input.

181.
Going Commando

182.
Command
class AddTaskCommand {
public $description;
public $priority;
public $todoListId;
}

183.
Controller
function addTaskAction($req) {
$command = new AddTaskCommand();
$command->description = $req->get('description');
$command->priority = $req->get('priority');
$command->todoListId = $req->get('todo_id');
$this->todoService->execute($command);
return $this->redirect('edit_page');
}
}

184.
Handler Foo
Controller Service Handler Bar
Handler Baz

185.
Controller Service
Handler Baz

186.
Service
class TodoListService {
}

187.
Service
class TodoListService {
function execute($command) {
}
}

188.
Service
class TodoListService {
function execute($command) {
get_class($command);
}
}

189.
Service
class TodoListService {
function execute($command) {
$command->getName();
}
}

190.
Service
class TodoListService {
function execute($command) {
$command->execute();
}
}

191.
Service
class TodoListService {
function execute($command) {
}
}

192.
What goes in a handler?

193.
Handler
class TodoListHandler {
function handleAddTask($cmd) {
$list = $this->repository->findById($cmd->todoListId);
$list->addTask($cmd->description, $cmd->priority);
}
function handleCompleteTask($command)
function handleRemoveTask($command)
}

194.
Service
class TodoListService {
function execute($command) {
}
}

195.
Service
class CommandBus {
function execute($command) {
}
}

196.
Service
class MyCommandBus implements CommandBus {
function execute($command) {
}
}

197.
Service
class ValidatingCommandBus implements CommandBus {
function execute($command) {
if (!$this->validator->isValid($command)) {
throw new InvalidCommandException();
}
$this->innerCommandBus->execute($command);
}
}

198.
Command
class AddTaskCommand {
public $description;
public $priority;
public $todoListId;
}

199.
Command
use SymfonyComponentValidatorConstraints as Assert;
class AddTaskCommand {
/** @AssertLength(max="50") */
public $description;
public $priority;
public $todoListId;
}

200.
Logging
Transactions
Event Dispatching

201.
Fewer Dependencies per class.
Simple layers.
Easy to test.

202.
View Models + Commands

203.
Model
Service Layer
Commands ViewModels
Controller
View

204.
forms
templates
validators
CRUD for the framework.
Domain Model for the chewy center.
tough logic
semantics
testing

205.
Diverge Further

206.
CQRS

207.
On the surface, it looks the same.

208.
Controller
function addTaskAction($req) {
$command = new AddTaskCommand();
$command->description = $req->get('description');
$command->priority = $req->get('priority');
$command->todoListId = $req->get('todo_id');
$this->commandBus->execute($command);
return $this->redirect('edit_page');
}
}

209.
CQS

210.
Commands = Change Data
Queries = Read Data

211.
CQRS

212.
Model
class TodoList {
function rename($name);
function addTask($desc, $priority);
function getName();
function getTasks();
}

213.
Two Models

214.
Write Model
class TodoListModel {
function rename($name);
function addTask($desc, $priority);
}
Read Model
class TodoListView {
function getName();
function getTasks();
}

215.
Model
class TodoList {
function rename($name);
function addTask($desc, $priority);
function getName();
function getTasks();
function getParticipatingUsers();
}

216.
Write Model
class TodoListModel {
function rename($name);
function addTask($desc, $priority);
}
Read Model
class TodoListView {
function getName();
function getTasks();
function getParticipatingUsers();
}

217.
Write Model
class TodoListModel {
function rename($name);
function addTask($desc, $priority);
}
Read Model
class TodoListView {
function getName();
function getTasks();
function getParticipatingUsers();
}
ORM entity
1 Model
SQL query
N Models

218.
Read and Write are two different systems.

219.
User and Shopping Cart?

220.
Same kind of split.

221.
Surrounding classes?

222.
A lot of it looks the same.

223.
Handler
class TodoListHandler {
function handleAddTask($cmd) {
$list = $this->repository->findById($cmd->todoListId);
$list->addTask($cmd->description, $cmd->priority);
}
}

224.
Service
class TodoListService {
public function findByUser(User $user) {
return $this->repository->findByUser($user);
}
}

225.
Handler
class TodoListHandler {
Service
class TodoListService {
public function findByUser(User $user) {
return $this->repository->findByUser($user);
}
}
function handleAddTask($cmd) {
$list = $this->repository->findById($cmd->todoListId);
$list->addTask($cmd->description, $cmd->priority);
}
}

226.
$todoList = new TodoList();
$this->repository->save($todoList);
$todoList->getId();
Controller

227.
$command = new CreateTodoCommand(UUID::create());
$commandBus->execute($command);
$command->uuid;
Controller

228.
Zoom Out

229.
Martin Fowler
waz here

230.
Domain
events

231.
DB Views

232.
Big
Honking
Queue

233.
github.com/beberlei/litecqrs-php/
github.com/qandidate-labs/broadway
github.com/gregoryyoung/m-r

234.
Pros & Cons

235.
Big mental leap.
Usually more LOC.
Not for every domain.
Can be mixed.

236.
Easy to Scale.
Bears Complexity.
Async Operations.
Event Sourcing.

237.
Event Sourcing?

238.
CQRS
+
Event Sourcing

239.
Instead of storing the current state in the db...

240.
...store the domain events?

241.
Snapshots
Debugging
Audit Log
Business Intelligence
Online/Offline users
Retroactively Fix Bugs

242.
Google it.
Or ask me afterwards.

243.
Epilogue

244.
"A foolish consistency is the hobgoblin of
little minds."
- Ralph Waldo Emerson

245.
Strong opinions, weakly held.

246.
Strong techniques, weakly held.

247.
PHP 3

248.
PHP 4 -5

249.
PHP 5.3+

250.
PHP 7

251.
Might seem crazy.

252.
Bang for the buck.

253.
People ARE doing this.

254.
It IS working for them.

255.
You can too.

256.
Questions?

257.
Further Reading
• codebetter.com/gregyoung
• martinfowler.com/tags/domain driven design.html
• shawnmc.cool/domain-driven-design
• whitewashing.de
• verraes.net

258.
Thanks To:
• Warnar Boekkooi @boekkooi
• Daan van Renterghem @DRvanR
• Matthijs van den Bos @matthijsvandenb

259.
Image Credits
• http://www.flickr.com/photos/calgaryreviews/6427412605/sizes/l/
• http://msnbcmedia.msn.com/j/MSNBC/Components/Slideshows/_production/twisp_090511_
/twisp_090511_02.ss_full.jpg
• http://shotthroughawindow.wordpress.com/2011/07/22/hp7b/
• http://www.sxc.hu/photo/605471
• http://martinfowler.com/bliki/images/cqrs/cqrs.png
• http://www.flickr.com/photos/83346641@N00/5578975430/in/photolist-9uZH2y-8rTZL1-di
xjR-ffBPiv-8SbK8K-ffS4md-6UeEGP
• http://www.flickr.com/photos/lac-bac/7195938394/sizes/o/
• http://tdzdaily.org/wp-content/uploads/2013/03/Dumb-and-Dumber.png
• http://upload.wikimedia.org/wikipedia/commons/1/17/Charlton_Heston_in_The_Ten_Comm
andments_film_trailer.jpg
• http://commons.wikimedia.org/wiki/File:Trench_construction_diagram_1914.png
• http://www.flickr.com/photos/jeffreyww/4747314852/sizes/l/
• http://www.flickr.com/photos/jdhancock/3540861791/sizes/l/
• http://www.flickr.com/photos/superfantastic/50088733/sizes/l

260.
joind.in/12101
Ross Tuck rosstuck.com
@rosstuck