Hexagonal Architecture

An explanation on what Hexagonal Architecture is - the decoupling of layers in your code.

Transcript

1. Hexagonal Architecture
   Chris Fidao
   (hek-sag-uh-nl)
   

   View Slide

2. @fideloper
   

   View Slide

3. View Slide

4. Implementing
   Laravel
   Real-world implementation of
   testable and maintainable
   code.
   (hopefully)
   

   View Slide

5. Vaprobash
   Vagrant Provisioning Bash Scripts
   

   View Slide

6. Servers for Hackers.com
   

   View Slide

7. Why / What
   Ports / Adapters
   Boundary Layers
   /
   

   View Slide

8. WHY
   Architecture
   

   View Slide

9. Maintainability
   Technical
   Debt
   Time
   

   View Slide

10. What is it?
    

    View Slide

11. So…What
    is it?
    

    View Slide

12. The Hexagon
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

13. (Core) Domain
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

14. Behavior
    

    View Slide

15. Constraints
    

    View Slide

16. Application
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

17. Framework
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

18. Outside
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

19. Ports Adapters
    /
    

    View Slide

20. Ports & Adapters
    Core
    Domain
    Application
    Domain
    Framework
    

    View Slide

21. Inside/Outside
    Core
    Domain
    Application
    Domain
    CommandBus
    Framework
    HTTP
    Use Case
    Repo
    DBAL
    Database
    Events
    Dispatcher
    Service Impl
    

    View Slide

22. Core
    Domain
    Application
    Domain
    Framework
    Dependencies
    

    View Slide

23. interface Notifier {
    !
    public function send(Message $message);
    }
    class SesNotifier implements Notifier {
    !
    public function send(Message $message) {
    // Details
    }
    }
    

    View Slide

24. Use-Case Driven
    Development
    

    View Slide

25. All the Contexts
    •Web
    •API
    •CLI
    •Queue
    •Event Handler
    

    View Slide

26. Use Cases:
    CommandBus
    CommandBus executes( )
    Command
    Handler handles( )
    Command
    

    View Slide

27. // Class SimpleCommandBus
    !
    public function execute( $command )
    {
    return $this->getHandler( $command )
    ->handle( $command );
    }
    Simple CommandBus
    

    View Slide

28. Core
    Domain
    Application
    Domain
    CommandBus
    Framework
    HTTP
    Use Case
    Repo
    DBAL
    Database
    Events
    Dispatcher
    Service Impl
    

    View Slide

29. View Slide

30. Boundaries
    

    View Slide

31. Domain/Application
    Boundary
    Core
    Domain
    Application
    Domain
    Framework
    Use Case
    Repo
    Events
    

    View Slide

32. interface CommandBusInterface {
    !
    public function execute( $command );
    }
    interface HandlerInterface {
    !
    public function handle( $command );
    }
    

    View Slide

33. Core
    Domain
    Application
    Domain
    Framework
    Use Case
    Repo
    Events
    

    View Slide

34. interface TicketRepositoryInterface {
    !
    public function getStaffOpenTickets(
    Staffer $staffer, $limit=10);
    !
    !
    public function save(Ticket $model);
    }
    

    View Slide

35. Application
    Domain
    CommandBus
    Framework
    DBAL
    Dispatcher
    The Application/External
    Boundary
    

    View Slide

36. interface Notifier {
    !
    public function send(Message $message);
    }
    interface Validator {
    !
    public function passes(Array $data);
    !
    public function getErrors();
    }
    interface Dispatcher {
    !
    public function dispatch(Array $events);
    }
    

    View Slide

37. Framework
    Core
    Domain
    Application
    Domain
    Framework
    HTTP
    Database
    Service Impl
    

    View Slide

38. Identify the aspects
    that vary and
    separate them from
    what stays the
    same
    

    View Slide

39. Layers
    

    View Slide

40. The Domain
    Core
    Domain
    Application
    Domain
    Framework
    Use Case
    Repo
    Events
    

    View Slide

41. !
    class Ticket extends Model {
    !
    public function assignStaffer(Staffer $staffer)
    {
    if( ! $staffer->categories->contains( $this->category ) )
    {
    throw new DomainException("Staffer can't be assigned to ".$this->category);
    }
    !
    $this->staffer()->associate($staffer); // Set Relationship
    !
    return $this;
    }
    !
    public function setCategory(Category $category)
    {
    if( $this->staffer instanceof Staffer &&
    ! $this->staffer->categories->contains( $category ) )
    {
    // Unset staffer if can't be assigned to set category
    $this->staffer = null;
    }
    !
    $this->category()->associate($category); // Set Relationship
    !
    return $this;
    }
    }
    

    View Slide

42. class Ticket extends Model {
    !
    /* ... Other logic ... */
    !
    public function save(array $options = array())
    {
    /* Integrity Checks, and then: */
    !
    if( ! $this->exists )
    {
    $this->raise( new TicketCreatedEvent($this) );
    }
    !
    return parent::save($options);
    }
    }
    

    View Slide

43. class CreateTicketCommand {
    !
    protected $data;
    !
    public function __construct($data)
    {
    $this->data = $data;
    }
    !
    public function __get($property)
    {
    // Simplified example
    return $this->data[$property];
    }
    }
    

    View Slide

44. The Application
    Application
    Domain
    CommandBus
    Framework
    DBAL
    Dispatcher
    

    View Slide

45. // Class SimpleCommandBus
    !
    public function execute( $command )
    {
    return $this->getHandler( $command )
    ->handle( $command );
    }
    

    View Slide

46. !
    class CreateTicketHandler implements HandlerInterface {
    !
    !
    public function handle($command)
    {
    $this->validate($command); // Throw ValidationException
    $this->save($command);
    }
    !
    protected function save($command)
    {
    $ticket = new Ticket;
    /* Some other setters... */
    $ticket->setCategory( $this->catRepo->find($command->category_id) );
    $ticket->setStaffer( $this->staffRepo->find($command->staffer_id) );
    $ticket->addMessage( $ticket->addMessage($command->message); );
    !
    $this->ticketRepo->save($ticket); // Use Repositories
    !
    $this->dispatcher->dispatch( $ticket->flushEvents() ); // Fire Events
    }
    }
    

    View Slide

47. class DbTicketRepository implements RepositoryInterface {
    !
    public function getStaffOpenTickets(Staffer $staffer, $limit=10)
    {
    return $this->ticket->where('staff_id', $staffer->id)
    ->take($limit)->get();
    }
    !
    public function save(Ticket $ticket)
    {
    $ticket->save();
    }
    }
    

    View Slide

48. Framework
    Core
    Domain
    Application
    Domain
    Framework
    HTTP
    Database
    Service Impl
    

    View Slide

49. class TicketController extends BaseController {
    !
    public function createTicket()
    {
    $command = new CreateTicketCommand( Input::all() );
    !
    try {
    $this->bus->execute($command);
    }
    catch(ValidationException $e)
    {
    return Redirect::to('/tickets/new')
    ->withErrors( $e->getErrors() );
    } catch(DomainException $e)
    {
    return Redirect::to('/tickets/new')
    ->withErrors( $e->getErrors() );
    }
    return Redirect::to(‘/tickets');
    }
    }
    

    View Slide

50. class SesEmailNotifier implements NotifierInterface {
    !
    public function __construct(SesClient $client)
    {
    $this->client = $client;
    }
    !
    public function send(Message $message)
    {
    $to = [$message->to()];
    $message = ['Data' => $message->message()];
    !
    $this->client->sendEmail([
    'Destination' => ['ToAddresses' => $to],
    'Message' => ['Body' => ['Html' => $message]]
    ]);
    }
    }
    

    View Slide

51. use Illuminate\Events\Dispatcher as EventDispatcher;
    !
    class LaravelDispatcher implements Dispatcher {
    !
    public function __construct(EventDispatcher $dispatcher)
    {
    $this->dispatcher = $dispatcher;
    }
    !
    public function dispatch(Array $events)
    {
    foreach( $events as $event )
    {
    $this->dispatcher->fire( $event->name(), $event );
    }
    }
    !
    }
    

    View Slide

52. TDD is DEAD
    (and other
    myths)
    

    View Slide

53. Identify the aspects
    that vary and
    separate them from
    what stays the
    same
    

    View Slide

54. Thanks
    

    View Slide