#297 Create API Gateway pattern

2026-05-14 22:58:36 +00:00 · 2016-02-07 17:05:33 -06:00
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+package com.iluwatar.api.gateway;
+
+/**
+ * With the Microservices pattern, a client may need data from multiple different microservices.
+ * If the client called each microservice directly, that could contribute to longer load times,
+ * since the client would have to make a network request for each microservice called. Moreover,
+ * having the client call each microservice directly ties the client to that microservice - if the
+ * internal implementations of the microservices change (for example, if two microservices are
+ * combined sometime in the future) or if the location (host and port) of a microservice changes,
+ * then every client that makes use of those microservices must be updated.
+ *
+ * <p>
+ * The intent of the API Gateway pattern is to alleviate some of these issues. In the API Gateway
+ * pattern, an additional entity (the API Gateway) is placed between the client and the
+ * microservices. The job of the API Gateway is to aggregate the calls to the microservices.
+ * Rather than the client calling each microservice individually, the client calls the API Gateway
+ * a single time. The API Gateway then calls each of the microservices that the client needs.
+ *
+ * <p>
+ * This implementation shows what the API Gateway pattern could look like for an e-commerce site.
+ * In this case, the (@link ImageService) and (@link PriceService) represent our microservices.
+ * Customers viewing the site on a desktop device can see both price information and an image of
+ * a product, so the (@link ApiGateway) calls both of the microservices and aggregates the data in
+ * the (@link DesktopProduct) model. However, mobile users only see price information; they do not
+ * see a product image. For mobile users, the (@link ApiGateway) only retrieves price information,
+ * which it uses to populate the (@link MobileProduct).
+ */
+public class App {
+
+  /**
+   * Program entry point
+   *
+   * @param args
+   *          command line args
+   */
+  public static void main(String[] args) {
+    ApiGateway apiGateway = new ApiGateway();
+
+    DesktopProduct desktopProduct = apiGateway.getProductDesktop();
+    System.out.println(String.format("Desktop Product \nPrice: %s\nImage path: %s",
+        desktopProduct.getPrice(), desktopProduct.getImagePath()));
+
+    MobileProduct mobileProduct = apiGateway.getProductMobile();
+    System.out.println(String.format("Mobile Product \nPrice: %s", mobileProduct.getPrice()));
+  }
+}