Fix for Issue #549 : Add Fallbacks in Aggregator Service (#971)

*  Fix for Issue##549

Catch ClientProtocolException and Update Error Logs

* Fix indentation, checkstyle errors

* Fix for Issue #549
Add fallbacks in Aggregator service when other microservices fail

* Make ProductInventoryClientImpl return null instead of zero in case of failure

Author: jarpit96

aggregator-microservices/aggregator-service/src/main/java/com/iluwatar/aggregator/microservices/Aggregator.java

@@ -51,9 +51,23 @@ public class Aggregator {
    */
   @RequestMapping(path = "/product", method = RequestMethod.GET)
   public Product getProduct() {
+
     var product = new Product();
-    product.setTitle(informationClient.getProductTitle());
-    product.setProductInventories(inventoryClient.getProductInventories());
+    String productTitle = informationClient.getProductTitle();
+    Integer productInventory = inventoryClient.getProductInventories();
+
+    if (productTitle != null) {
+      product.setTitle(productTitle);
+    } else {
+      product.setTitle("Error: Fetching Product Title Failed"); //Fallback to error message
+    }
+
+    if (productInventory != null) {
+      product.setProductInventories(productInventory);
+    } else {
+      product.setProductInventories(-1); //Fallback to default error inventory
+    }
+
     return product;
   }
 

aggregator-microservices/aggregator-service/src/main/java/com/iluwatar/aggregator/microservices/ProductInventoryClient.java

@@ -28,5 +28,5 @@
  */
 public interface ProductInventoryClient {
 
-  int getProductInventories();
+  Integer getProductInventories();
 }

aggregator-microservices/aggregator-service/src/main/java/com/iluwatar/aggregator/microservices/ProductInventoryClientImpl.java

@@ -42,8 +42,8 @@ public class ProductInventoryClientImpl implements ProductInventoryClient {
   private static final Logger LOGGER = LoggerFactory.getLogger(ProductInventoryClientImpl.class);
 
   @Override
-  public int getProductInventories() {
-    var response = "0";
+  public Integer getProductInventories() {
+    var response = "";
 
     var request = HttpRequest.newBuilder().GET().uri(URI.create("http://localhost:51516/inventories")).build();
     var client = HttpClient.newHttpClient();
@@ -55,6 +55,10 @@ public int getProductInventories() {
     } catch (InterruptedException ie) {
       LOGGER.error("InterruptedException Occurred", ie);
     }
-    return Integer.parseInt(response);
+    if("".equalsIgnoreCase(response)) {
+        return null;
+    } else {
+        return Integer.parseInt(response);
+    }
   }
 }