Our reference database can be seen from the IDE by clicking on the Services panel. Under the Databases menu that is part of the Services tab, double-click on the jdbc:derby://localhost:1527/sample [app on APP] Database Connection link to connect to the sample database on port 1527 (the default port for Derby databases) with the app user on the APP schema. Under the APP schema, you should find seven tables including CUSTOMER and PRODUCT. By right-clicking on the CUSTOMER table and choosing View Data…, you should be able to browse the content of the table.

The following diagram depicts the whole database schema so that you can visualize the dependencies or foreign keys between the different tables:

To quickly set up our sample Java project, you may either import it directly in your favorite IDE from the downloaded code (and skip creating JPA entities and the REST web service) or perform the following simple steps on the NetBeans IDE:

Right-click on the Sample project root we just created and navigate to New | RESTful Web Services from Databases…. Selecting the derby sample database connection from the drop-down list in the newly opened window should bring up the database tables into the Available Tables section. Mark only the CUSTOMER table and select Add>, both CUSTOMER and DISCOUNT_CODE (which are dependent on CUSTOMER) should be listed as Selected Tables, as shown in the following screenshot:

Clicking on the Next button and again on Next on the next page, and finally clicking on Finish will generate both the persistence JPA entities for Customer and DiscountCode and the service facade classes, CustomerFacadeREST and DiscountCodeFacadeREST. Note that since Java EE6, the EntityManager class is instantiated in each service class, which avoids the need for JPA controller classes that were generated in the previous versions.

Before we start introducing Scala code into our Java project, we may launch our application and test REST invocations in a browser. Right-click on the Sample root node of the project and select Run to deploy the application. Once the console displays that the GlassFish server is running, and that the message Hello World! appears in your browser to show that everything is deployed correctly, right-click on the RESTful Web Services folder under the project root, and select Test RESTful Web Services. The opening dialog lets you choose between generating a test client as part of the same project or externally, as shown in the following screenshot:

Select Locally Generated Test Client (suitable for Internet Explorer) and click on OK.

Once deployment completes, the browser will display a test page where we can invoke REST methods on our customer and discountcode entities. If we expand the com.demo.sample.customer folder, additional parameters will be shown. Clicking on the {id} parameter, we will get an input field on the right pane where we can enter a particular customer id value. For instance, we can enter 409. In the drop-down list that shows MIME types, select application/json and GET as the method to test, and then click on Test, as shown in the following screenshot:

The bottom part of the page will now display the response to the REST query. It consists of a Status: 200 (OK) message and a Response content where the Raw View tab will display the body of the response as JSON, as shown in the previous screenshot.

> mvn test
-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.demo.sample.CustomerTest
getCustomerId
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.034 sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0