Hexagonal / Ports and Adapters Is Just This Simple

CONTENTS.md

Hexagonal / Ports and Adapters Is Just This Simple

Navigation

OUTSIDE

1. PersonResource Driver-Side Adapter
2. PostgresPersonRepository Driven-Side Adapter

INSIDE

Application

1. PersonService Input Port
2. PersonData

Model

1. Person
2. PersonRepository Output Port

Person.java

//=====================================
// INSIDE
//=====================================

//
// Inside: Model: Person
//
package people.model.person;

public class Person extends Entity {
  private String id;
  private String name;
  private String emailAddress;
  
  public static Person with(String name, String emailAddress) {
    return new Person(name, emailAddress);
  }
  
  public String id() {
    return this.id;
  }
  
  public void changeName(String name) {
    this.name = name;
  }
  
  public String name() {
    return this.name;
  }
  
  public void changeEmailAddress(String emailAddress) {
    this.emailAddress = emailAddress;
  }
  
  public String emailAddress() {
    return this.emailAddress;
  }
  
  private Person(String name, String emailAddress) {
    this.id = uniqueId();
    this.name = name;
    this.emailAddress = emailAddress;
  }
}

PersonData.java

//=====================================
// INSIDE
//=====================================

//
// Inside: Application: PersonData
//
package people.application.data;

public final class PersonData {
  public final String id;
  public final String name;
  public final String emailAddress;
  
  public static PersonData from(Person person) {
    return new PersonData(person.id(), person.name(), person.emailAddress());
  }
  
  private PersonData(String id, String name, String emailAddress) {
    this.id = id;
    this.name = name;
    this.emailAddress = emailAddress;
  }
}

PersonRepository.java

//=====================================
// INSIDE: Output Port
//=====================================

//
// Inside Driven-side Port: Model: PersonRepository
//
package people.model.person;

public interface PersonRepository {
  public void add(Person person);
  public Person personOf(String personId);
}

PersonResource.java

//=====================================
// OUTSIDE: Driver-Side Adapter
//=====================================

//
// Outside: Driver-side HTTP Adapter: PersonResource
//
package people.infrastructure.resource;

public class PersonResource extends Resource {
  private PersonService service;
  
  public PersonResource(PersonService service) {
    this.service = service;
  }
  
  public Respose get(String personId) {
    PersonData person = service.personOf(personId);
    return Response.ok(serialize(person));
  }
  
  public Response post(String name, String emailAddress) {
    PersonData person = service.personFrom(name, emailAddress);
    return Response.created(serialize(person), Header.of(Header.Location, pathOf(person)));
  }
  
  public Response patchName(String personId, String name) {
    PersonData person = service.changeName(personId, name);
    return Response.ok(serialize(person));
  }
  
  public Response patchEmailAddress(String personId, String emailAddress) {
    PersonData person = service.changeEmailAddress(personId, emailAddress);
    return Response.ok(serialize(person));
  }
}

PersonService.java

//=====================================
// INSIDE: Input Port
//=====================================

//
// Inside Driver-side Port: Application: PersonService
//
package people.application;

public class PersonService extends ApplicationService {() {
  private PersonRepository repository;
  
  public PersonService(PersonRepository repository) {
    this.repository = repository;
  }

  @Transactional(READ_ONLY)
  public PersonData personOf(String personId) {
    Person person = repository.personOf(personId);
    return PersonData.from(person);
  }
  
  @Transactional
  public PersonData personFrom(String name, String emailAddress) {
    Person person = Person.with(name, emailAddress);
    repository.add(person);
    return PersonData.from(person);
  }

  @Transactional
  public PersonData changeName(String personId, String name) {
    Person person = repository.personOf(personId);
    person.changeName(name);
    return PersonData.from(person);
  }

  @Transactional
  public PersonData changeEmailAddress(String personId, String emailAddress) {
    Person person = repository.personOf(personId);
    person.changeEmailAddress(emailAddress);
    return PersonData.from(person);
  }
}

PostgresPersonRespository.java

//=====================================
// OUTSIDE: Driven-Side Adapter
//=====================================

//
// Outside: Driven-side Persistence Adapter: PostgresPersonRepository
//
package people.infrastructure.persistence;

public class PostgresPersonRepository extends Repository implements PersonRepository {
  private Session session;
  
  public PostgresPersonRepository(Session session) {
    this.session = session;
  }
  
  public void add(Person person) {
    session.save(person);
  }
  
  public Person personOf(String personId) {
    Person person = session.get(personId, Person.class);
    return person;
  }
}

Improved comments on architecture roles.