Hexagonal architecture - message-oriented software design (PHP Benelux 2016)
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The document discusses the concept of hexagonal architecture in software design, emphasizing the importance of separating concerns to minimize coupling to frameworks and delivery mechanisms. It highlights the need for a domain model and interaction processes while treating databases as implementation details. The conclusion focuses on the benefits of intention-revealing code and reusable infrastructure to support flexible software architecture.
![Low-level API
$requestContent = file_get_contents('php://input');
$contentType = $_SERVER['CONTENT_TYPE'];
if ($contentType === 'application/json') {
$data = json_decode($requestContent, true);
} elseif ($contentType === 'application/xml') {
$xml = simplexml_load_string($requestContent);
...
}](https://image.slidesharecdn.com/hexagonalarchitecture-message-orientedsoftwaredesign-160130093744/85/Hexagonal-architecture-message-oriented-software-design-PHP-Benelux-2016-12-320.jpg)
!["A good software architecture allows decisions [...]
to be deferred and delayed."
–Robert Martin, Screaming Architecture](https://image.slidesharecdn.com/hexagonalarchitecture-message-orientedsoftwaredesign-160130093744/85/Hexagonal-architecture-message-oriented-software-design-PHP-Benelux-2016-70-320.jpg)
Hexagonal architecture - message-oriented software design (PHP Benelux 2016)
- 1. HEXAGONAL ARCHITECTURE Message oriented software design By Matthias Noback
- 3. Nice app
- 4. Sad app
- 5. Your brain can't handle it M V C ?
- 6. Coupling to frameworks and libraries
- 7. How do you start a new project? Pick a framework Install a skeleton project Remove demo stuff Auto-generate entities Auto-generate CRUD controllers Done "It's a Symfony project!"
- 8. That's actually outside in The boring stuff The interesting stuff Symfony Doctrine RabbitMQ Redis Angular
- 10. Why do frameworks not solve this for us? Because they can't ;)
- 12. Low-level API $requestContent = file_get_contents('php://input'); $contentType = $_SERVER['CONTENT_TYPE']; if ($contentType === 'application/json') { $data = json_decode($requestContent, true); } elseif ($contentType === 'application/xml') { $xml = simplexml_load_string($requestContent); ... }
- 13. Nicely hides the details $data = $serializer->deserialize( $request->getContent(), $request->getContentType() );
- 14. Low-level API $stmt = $db->prepare( 'SELECT * FROM Patient p WHERE p.anonymous = ?' ); $stmt->bindValue(1, true); $stmt->execute(); $result = $stmt->fetch(PDO::FETCH_ASSOC); $patient = Patient::reconstituteFromArray($result);
- 15. Hides a lot of details $patient = $repository->createQueryBuilder('p') ->where('p.anonymous = true') ->getQuery() ->getResult();
- 17. $patient = $repository->createQueryBuilder('p') ->where('p.anonymous = true') ->getQuery() ->getResult(); Concrete Concrete Concrete
- 19. Coupling to the delivery mechanism
- 20. public function registerPatientAction(Request $request) { $patient = new Patient(); $form = $this->createForm(new RegisterPatientForm(), $patient); $form->handleRequest($request); if ($form->isValid()) { $em = $this->getDoctrine()->getManager(); $em->persist($patient); $em->flush(); return $this->redirect($this->generateUrl('patient_list')); } return array( 'form' => $form->createView() ); } Request and Form are web-specific EntityManager is ORM, i.e. relational DB-specific
- 24. Lack of intention-revealing code
- 25. data data data
- 26. public function updateAction(Request $request) { $patient = new Patient(); $form = $this->createForm(new PatientType(), $patient); $form->handleRequest($request); if ($form->isValid()) { $em = $this->getDoctrine()->getManager(); $em->persist($patient); $em->flush(); return $this->redirect($this->generateUrl('patient_list')); } return array( 'form' => $form->createView() ); } from the HTTP request copied into an entity then stored in the database What exactly changed?! And... why?
- 27. R.A.D. Rapid Application Development B.A.D. B.A.D. Application Development
- 28. In summary Coupling to a framework Coupling to a delivery mechanism (e.g. the web) Slow tests Lack of intention in the code
- 29. THE ESSENCE of your application
- 31. The "heart"?
- 32. "The heart of software is its ability to solve domain-related problems for its users. –Eric Evans, Domain Driven Design All other features, vital though they may be, support this basic purpose."
- 33. What's essential? Domain model Interaction with it Use cases
- 35. “The database is an implementation detail” –Cool software architect
- 36. The core doesn't need to know about it
- 38. The core doesn't need to know about it
- 39. Infrastructure The world outside Web browser Terminal Database Messaging Filesystem (E)mail
- 40. Mmm... layers Layers allow you to separate Layers allow you to allocate Layers have boundaries Rules for crossing
- 41. Rules about communication Actually: rules about dependencies
- 42. The dependency rule –Robert Martin, Screaming Architecture
- 44. Messages someFunctionCall( $arguments, $prepared, $for, $the, $receiver ); $message = new TypeOfMessage( $some, $relevant, $arguments ); handle($message);
- 45. What about the application boundary? The app Message The world outside
- 46. How does an app allow incoming messages at all? By exposing input ports Routes Console commands A WSDL file for a SOAP API
- 49. Ports use protocols for communication Each port has a language of its own
- 50. Web (HTTP)
- 51. Messaging (AMQP)
- 52. HTTP Request Form Request Controller Entity Value object W eb port Translate the request Repository
- 53. Adapters The translators are called: adapters
- 54. "Ports and adapters" Ports: allow for communication to happen Adapters: translate messages from the world outside == Hexagonal architecture Alistair Cockburn
- 55. An example Plain HTTP message $_POST, $_GET, $_SERVER, Request POST /patients/ HTTP/1.1 Host: hospital.com name=Matthias&email=matthiasn oback@gmail.com Command $command = new RegisterPatient( $request->get('name'), $request->get('email') );
- 56. Command $command = new RegisterPatient( $request->get('name'), $request->get('email') ); Expresses intention Implies change Independent of delivery mechanism Only the message
- 57. class RegisterPatientHandler { public function handle(RegisterPatient $command) { $patient = Patient::register( $command->name(), $command->email() ); $this->patientRepository->add($patient); } } Command Command handler
- 60. Change New entity (Patient) Entity- Manager UnitOf- Work $patient = Patient::register( $command->name(), $command->email() ); $this->patientRepository ->add($patient); Insert query (SQL) INSERT INTO patients SET name='Matthias', email='matthiasnoback@gmai l.com';
- 64. What often goes wrong: we violate boundary rules...
- 67. PatientRepository (uses MySQL) Domain Infrastructure Application Domain RegisterPatient- Handler
- 70. "A good software architecture allows decisions [...] to be deferred and delayed." –Robert Martin, Screaming Architecture
- 71. IN CONCLUSION what did we get from all of this?
- 75. This is all very much supportive of... See also: Modelling by Example DDD TDD BDD CQRS