@startuml GatewayPattern
package com.iluwatar.gateway{
class App {
  +main(args: String[]): void
}

class GatewayFactory {
  -gateways: Map<String, Gateway>
  +registerGateway(key: String, gateway: Gateway): void
  +getGateway(key: String): Gateway
}

interface Gateway {
  {abstract} +execute(): void
}

class ExternalServiceA {
  +execute(): void
}

class ExternalServiceB {
  +execute(): void
}

class ExternalServiceC {
  +execute(): void
  +error(): void
}

App --> GatewayFactory : Uses


GatewayFactory --> Gateway : Creates

GatewayFactory --> ExternalServiceA : Registers
GatewayFactory --> ExternalServiceB : Registers
GatewayFactory --> ExternalServiceC : Registers

ExternalServiceA --> Gateway : Implements
ExternalServiceB --> Gateway : Implements
ExternalServiceC --> Gateway : Implements

@enduml