Data Aggregation in API Gateway - Zuul

Question

I'm looking for a solution that would provide kind of data Aggregation in API Gateway. I am using spring cloud netflix zuul for API gateway. I created 3 micro services using spring boot -

Catalog - All products 
DeviceInfo - a particular product detail 
Inventory - product stock

Here is Zuul configuration -

zuul.routes.deviceInfo.path=/device/deviceInfo/**
zuul.routes.deviceInfo.url=http://localhost:9002/getDeviceInfo

zuul.routes.catalog.path=/device/all/**
zuul.routes.catalog.url=http://localhost:9001/getProductCatalog

zuul.routes.inventory.path=/device/stock/**
zuul.routes.inventory.url=http://localhost:9003/getInventory

ribbon.eureka.enabled=false

server.port=8080

In product detail page I need to make two calls -

http://localhost:8080/device/deviceInfo/ - for product details
http://localhost:8080/device/stock/ - for stock details

Is there any way to make a single call to API gateway which will combine the results of above two calls? Both calls are giving JSON in response.

Answer 1

You may use aggregator-microservices pattern but not in ZUUL. Keep Zuul as stateless gateway. Aggregator microservice should have client code like this

public String getProductTitle() {
    String response = null;
    try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
      HttpGet httpGet = new HttpGet("http://localhost:51515/information");
      try (CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {
        response = EntityUtils.toString(httpResponse.getEntity());
      }
    } catch (IOException e) {
      LOGGER.error("Exception caught.", e);
    }
    return response;
  }
}

Please have look at https://github.com/iluwatar/java-design-patterns/tree/master/aggregator-microservices