mirror of
https://github.com/tiennm99/java-design-patterns.git
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Ilkka Seppälä
148 lines
4.3 KiB
Markdown
148 lines
4.3 KiB
Markdown
---
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title: Gateway
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shortTitle: Gateway
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category: Structural
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language: es
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tag:
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- Decoupling
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---
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## Propósito
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Proporcionar una interfaz de acceso a un conjunto de sistemas o funcionalidades externas. Gateway proporciona una vista simple y uniforme de
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recursos externos a los internos de una aplicación.
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## Explicación
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Un ejemplo real
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> Gateway actúa como una verdadera puerta de entrada de una ciudad determinada. Las personas dentro de la ciudad se llaman sistema interno, y las diferentes ciudades externas se llaman servicios externos. La puerta de enlace está aquí para proporcionar acceso al sistema interno a diferentes servicios externos.
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En pocas palabras
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> La pasarela puede proporcionar una interfaz que permita al sistema interno utilizar un servicio externo.
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Wikipedia dice
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> Un servidor que actúa como front-end de la API, recibe solicitudes de la API, aplica políticas de estrangulamiento y seguridad, pasa las solicitudes al servicio back-end y, a continuación, devuelve la respuesta al solicitante.
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**Ejemplo programático**
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La clase principal de nuestro ejemplo es el `ExternalService` que contiene elementos.
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```java
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class ExternalServiceA implements Gateway {
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@Override
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public void execute() throws Exception {
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LOGGER.info("Executing Service A");
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// Simulate a time-consuming task
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Thread.sleep(1000);
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}
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}
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/**
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* ExternalServiceB is one of external services.
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*/
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class ExternalServiceB implements Gateway {
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@Override
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public void execute() throws Exception {
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LOGGER.info("Executing Service B");
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// Simulate a time-consuming task
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Thread.sleep(1000);
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}
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}
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/**
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* ExternalServiceC is one of external services.
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*/
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class ExternalServiceC implements Gateway {
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@Override
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public void execute() throws Exception {
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LOGGER.info("Executing Service C");
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// Simulate a time-consuming task
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Thread.sleep(1000);
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}
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public void error() throws Exception {
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// Simulate an exception
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throw new RuntimeException("Service C encountered an error");
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}
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}
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```
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Para operar estos servicios externos, aquí está la clase `App`:
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```java
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public class App {
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/**
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* Simulate an application calling external services.
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*/
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public static void main(String[] args) throws Exception {
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GatewayFactory gatewayFactory = new GatewayFactory();
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// Register different gateways
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gatewayFactory.registerGateway("ServiceA", new ExternalServiceA());
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gatewayFactory.registerGateway("ServiceB", new ExternalServiceB());
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gatewayFactory.registerGateway("ServiceC", new ExternalServiceC());
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// Use an executor service for asynchronous execution
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Gateway serviceA = gatewayFactory.getGateway("ServiceA");
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Gateway serviceB = gatewayFactory.getGateway("ServiceB");
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Gateway serviceC = gatewayFactory.getGateway("ServiceC");
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// Execute external services
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try {
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serviceA.execute();
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serviceB.execute();
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serviceC.execute();
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} catch (ThreadDeath e) {
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LOGGER.info("Interrupted!" + e);
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throw e;
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}
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}
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}
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```
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La interfaz `Gateway` es extremadamente sencilla.
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```java
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interface Gateway {
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void execute() throws Exception;
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}
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```
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Salida del programa:
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```java
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Executing Service A
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Executing Service B
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Executing Service C
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```
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## Diagrama de clases
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## Aplicabilidad
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Utilizar el patrón Gateway
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* Para acceder al contenido de un objeto agregado sin exponer su representación interna.
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* Para la integración con múltiples servicios externos o APIs.
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* Para proporcionar una interfaz uniforme para recorrer diferentes estructuras de agregados.
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## Tutoriales
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* [Pattern: API Gateway / Backends for Frontends](https://microservices.io/patterns/apigateway.html)
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## Usos conocidos
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* [API Gateway](https://java-design-patterns.com/patterns/microservices-api-gateway/)
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* [10 most common use cases of an API Gateway](https://apisix.apache.org/blog/2022/10/27/ten-use-cases-api-gateway/)
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## Créditos
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* [Gateway](https://martinfowler.com/articles/gateway-pattern.html)
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* [What is the difference between Facade and Gateway design patterns?](https://stackoverflow.com/questions/4422211/what-is-the-difference-between-facade-and-gateway-design-patterns)
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