Hexagonal Architecture

Transcript

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

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   @fideloper

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   None
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   Implementing Laravel Real-world implementation of testable and maintainable code. (hopefully)

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   Vaprobash Vagrant Provisioning Bash Scripts

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   Servers for Hackers.com

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   Why / What Ports / Adapters Boundary Layers /

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   WHY Architecture

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   Maintainability Technical Debt Time

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    What is it?

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    So…What is it?

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    The Hexagon Core Domain Application Domain Framework

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    (Core) Domain Core Domain Application Domain Framework

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    Behavior

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    Constraints

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    Application Core Domain Application Domain Framework

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    Framework Core Domain Application Domain Framework

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    Outside Core Domain Application Domain Framework

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    Ports Adapters /

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    Ports & Adapters Core Domain Application Domain Framework

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    Inside/Outside Core Domain Application Domain CommandBus Framework HTTP Use Case

    Repo DBAL Database Events Dispatcher Service Impl
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    Core Domain Application Domain Framework Dependencies

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    interface Notifier { ! public function send(Message $message); } class

    SesNotifier implements Notifier { ! public function send(Message $message) { // Details } }
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    Use-Case Driven Development

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

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

    Command
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    // Class SimpleCommandBus ! public function execute( $command ) {

    return $this->getHandler( $command ) ->handle( $command ); } Simple CommandBus
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    Core Domain Application Domain CommandBus Framework HTTP Use Case Repo

    DBAL Database Events Dispatcher Service Impl
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    None
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    Boundaries

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    Domain/Application Boundary Core Domain Application Domain Framework Use Case Repo

    Events
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    interface CommandBusInterface { ! public function execute( $command ); }

    interface HandlerInterface { ! public function handle( $command ); }
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    Core Domain Application Domain Framework Use Case Repo Events

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    interface TicketRepositoryInterface { ! public function getStaffOpenTickets( Staffer $staffer, $limit=10);

    ! ! public function save(Ticket $model); }
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    Application Domain CommandBus Framework DBAL Dispatcher The Application/External Boundary

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    interface Notifier { ! public function send(Message $message); } interface

    Validator { ! public function passes(Array $data); ! public function getErrors(); } interface Dispatcher { ! public function dispatch(Array $events); }
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    Framework Core Domain Application Domain Framework HTTP Database Service Impl

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    Identify the aspects that vary and separate them from what

    stays the same
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    Layers

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    The Domain Core Domain Application Domain Framework Use Case Repo

    Events
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    <?php namespace Hex\Tickets; ! 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; } }
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    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); } }
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    class CreateTicketCommand { ! protected $data; ! public function __construct($data)

    { $this->data = $data; } ! public function __get($property) { // Simplified example return $this->data[$property]; } }
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    The Application Application Domain CommandBus Framework DBAL Dispatcher

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    // Class SimpleCommandBus ! public function execute( $command ) {

    return $this->getHandler( $command ) ->handle( $command ); }
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    ! 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 } }
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    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(); } }
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    Framework Core Domain Application Domain Framework HTTP Database Service Impl

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    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'); } }
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    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]] ]); } }
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    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 ); } } ! }
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    TDD is DEAD (and other myths)

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    Identify the aspects that vary and separate them from what

    stays the same
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    Thanks