java-design-patterns/onion-architecture/etc/onion-architecture.puml

@startuml onion-architecture

skinparam packageStyle rectangle
skinparam shadowing false
skinparam defaultFontName Arial
skinparam defaultFontSize 11
skinparam classAttributeIconSize 0
skinparam ArrowColor #444444
skinparam ArrowThickness 1.2

skinparam package {
  BackgroundColor<<domain>>         #FFF9C4
  BorderColor<<domain>>             #F9A825
  FontColor<<domain>>               #5D4037
  FontStyle<<domain>>               bold
}

skinparam package {
  BackgroundColor<<application>>    #C8E6C9
  BorderColor<<application>>        #388E3C
  FontColor<<application>>          #1B5E20
  FontStyle<<application>>          bold
}

skinparam package {
  BackgroundColor<<infrastructure>> #BBDEFB
  BorderColor<<infrastructure>>     #1976D2
  FontColor<<infrastructure>>       #0D47A1
  FontStyle<<infrastructure>>       bold
}

' ─────────────────────────────────────────────────────────────────────────────
' DOMAIN LAYER (innermost)
' ─────────────────────────────────────────────────────────────────────────────
package "Domain Layer" <<domain>> {

  package "model" {
    class Person {
      - id : Long
      - firstName : String
      - lastName : String
      - age : int
      - phoneNumber : String
      - email : String
      - category : Category
      + getId() : Long
      + getFirstName() : String
      + getLastName() : String
      + getAge() : int
      + getPhoneNumber() : String
      + getEmail() : String
      + getCategory() : Category
    }

    class Category {
      - id : Long
      - type : String
      + getId() : Long
      + getType() : String
    }
  }

  package "repository" {
    interface PersonRepository {
      + findById(id : Long) : Optional<Person>
      + findByFirstName(firstName : String) : Optional<Person>
      + findByLastName(lastName : String) : Optional<Person>
      + findAll() : Optional<List<Person>>
      + save(person : Person) : Person
      + deleteById(id : Long) : boolean
    }
  }

  package "exception" {
    class DomainException {
      + DomainException(message : String)
    }
  }
}

' ─────────────────────────────────────────────────────────────────────────────
' APPLICATION LAYER
' ─────────────────────────────────────────────────────────────────────────────
package "Application Layer" <<application>> {

  package "usecase" {
    class SavePersonUseCase {
      - repository : PersonRepository
      + SavePersonUseCase(repository : PersonRepository)
      + execute(command : SavePersonCommand) : PersonResponse
    }

    class GetPersonUseCase {
      - repository : PersonRepository
      + GetPersonUseCase(repository : PersonRepository)
      + execute(id : Long) : PersonResponse
      + executeAll() : List<PersonResponse>
    }
  }

  package "dto" {
    class SavePersonCommand <<record>> {
      firstName : String
      lastName : String
      age : int
      phoneNumber : String
      email : String
      address : String
      categoryId : Long
      categoryType : String
    }

    class PersonResponse <<record>> {
      id : Long
      firstName : String
      lastName : String
      age : int
      phoneNumber : String
      email : String
      categoryId : Long
      categoryType : String
    }
  }
}

' ─────────────────────────────────────────────────────────────────────────────
' INFRASTRUCTURE LAYER (outermost)
' ─────────────────────────────────────────────────────────────────────────────
package "Infrastructure Layer" <<infrastructure>> {

  package "web" {
    class PersonController {
      - savePersonUseCase : SavePersonUseCase
      - getPersonUseCase : GetPersonUseCase
      + getPerson(id : Long) : ResponseEntity<PersonResponse>
      + getAllPersons() : ResponseEntity<List<PersonResponse>>
      + savePerson(command : SavePersonCommand) : ResponseEntity<PersonResponse>
    }
  }

  package "persistence" {
    class PersonRepositoryAdapter {
      - repository : SpringDataPersonRepository
      + findById(id : Long) : Optional<Person>
      + findByFirstName(firstName : String) : Optional<Person>
      + findByLastName(lastName : String) : Optional<Person>
      + findAll() : Optional<List<Person>>
      + save(person : Person) : Person
      + deleteById(id : Long) : boolean
    }

    interface SpringDataPersonRepository {
      + findByFirstName(firstName : String) : Optional<JpaPersonEntity>
      + findByLastName(lastName : String) : Optional<JpaPersonEntity>
    }

    class JpaPersonEntity {
      - id : Long
      - firstName : String
      - lastName : String
      - age : int
      - phoneNumber : String
      - email : String
      - category : JpaCategoryEntity
    }

    class JpaCategoryEntity {
      - id : Long
      - type : String
    }
  }

  package "config" {
    class ApplicationConfig <<@Configuration>> {
      + savePersonUseCase(repo : PersonRepository) : SavePersonUseCase
      + getPersonUseCase(repo : PersonRepository) : GetPersonUseCase
    }

    class Application <<@SpringBootApplication>> {
      + main(args : String[])
    }
  }
}

' ─────────────────────────────────────────────────────────────────────────────
' DOMAIN: internal relationships
' ─────────────────────────────────────────────────────────────────────────────
Person "1" *-- "1" Category : has
Person ..> DomainException : <<throws>>
Category ..> DomainException : <<throws>>

' ─────────────────────────────────────────────────────────────────────────────
' APPLICATION → DOMAIN
' ─────────────────────────────────────────────────────────────────────────────
SavePersonUseCase --> PersonRepository : uses
SavePersonUseCase ..> Person : creates
SavePersonUseCase ..> Category : creates
SavePersonUseCase ..> PersonResponse : returns
SavePersonUseCase ..> SavePersonCommand : receives

GetPersonUseCase --> PersonRepository : uses
GetPersonUseCase ..> PersonResponse : returns

' ─────────────────────────────────────────────────────────────────────────────
' INFRASTRUCTURE → APPLICATION / DOMAIN
' ─────────────────────────────────────────────────────────────────────────────
PersonController --> SavePersonUseCase : delegates to
PersonController --> GetPersonUseCase : delegates to
PersonController ..> DomainException : catches

PersonRepositoryAdapter ..|> PersonRepository : implements
PersonRepositoryAdapter --> SpringDataPersonRepository : uses
PersonRepositoryAdapter ..> JpaPersonEntity : maps
PersonRepositoryAdapter ..> JpaCategoryEntity : maps
PersonRepositoryAdapter ..> Person : maps to / from
PersonRepositoryAdapter ..> Category : maps to / from

SpringDataPersonRepository --> JpaPersonEntity : manages
JpaPersonEntity "1" *-- "1" JpaCategoryEntity : contains

ApplicationConfig ..> SavePersonUseCase : <<@Bean>>
ApplicationConfig ..> GetPersonUseCase : <<@Bean>>
ApplicationConfig --> PersonRepository : injects

legend right
  <b>Layer dependency rule</b>
  Infrastructure  →  Application  →  Domain
  Outer layers depend on inner layers.
  Domain has NO external dependencies.
  ----
  <color:#F9A825>■</color> Domain Layer
  <color:#388E3C>■</color> Application Layer
  <color:#1976D2>■</color> Infrastructure Layer
endlegend

@enduml