Consuming external OData service from CAP Java application

In this blog, I am covering consuming an external OData service (Northwind) from a CAP Java application using SAP BTP destination service.

Destinations: contain the connection details for the remote communication of an application.

Pre-requisites: 

• Trial account on BTP
• Java application built using SAP Cloud Application Programming Model (CAP) deployed to SAP Business Technology Platform.

Create a Destination on BTP cockpit:

• Go to BTP subaccount -> space in which app is deployed -> instances -> create

Create destination service instance

• Once the service instance is created, click on instance name -> select destinations -> new destination

• Go to Referencing apps -> Click on bind instance -> select name of deployed application -> save

Consuming the destination in java code:

• Add/make sure this dependency is added you your pom.xml

•  We have already configured the connection information with destination northwind_api. SAP Cloud SDK provides DestinationAccessor to retrieve destination info.

@RequestMapping(value = "/getProducts")
    public String getProducts() {
        String DESTINATION_NAME = "northwind_api"; 
                                                        
        try {
            HttpDestination destination =
                    DestinationAccessor.getDestination(DESTINATION_NAME).asHttp();
            HttpClient client = HttpClientAccessor.getHttpClient(destination);
            HttpResponse httpResponse = null;
            try {
                httpResponse = client.execute(new HttpGet());
                if (httpResponse.getStatusLine().getStatusCode() == 200) {
                    BufferedReader reader = new BufferedReader(
                            new InputStreamReader(httpResponse.getEntity().getContent()));
                    StringBuilder result = new StringBuilder();
                    String line = null;
                    while ((line = reader.readLine()) != null) {
                        result.append(line);
                    }
                    reader.close();
                    return result.toString();
                }
            } catch (IOException e) {
                return "IOException: " + e.getMessage();
            }
        } catch (DestinationNotFoundException | DestinationAccessException e) {
            return e.getMessage();
        }
        return null;
    }

• Got the response as below on hitting “/getProducts” endpoint
• 

Closing:

This blog should give you a clear idea on how to consume destinations in SAP Cloud Platform Cloud Foundry environment from java code using DestinationAccessor class provided by SAP cloud SDK.