Web services are APIs which, in the case of this recipe, access some data over a network from any platform and using any programming language.
In the world of cloud computing, web services have become an increasingly popular way for companies to let developers create applications using their data. A good example of this is Twitter. Thanks to exposition of Twitter data through web services, it has been possible to create numerous Twitter clients on virtually all platforms. In this recipe, we will create a web service that returns information from a database table; we will see that this information can be transferred either in XML or JavaScript Object Notation (JSON) format. JSON provides the user with data access simplicity, when compared to XML, since it does not need a bunch of tags and nested tags to work Getting ready
It is required to have NetBeans with Java EE support installed to continue with this recipe.
If this particular NetBeans version is not available in your machine, please visit:
We will use the GlassFish Server in this recipe since it is the only server that supports Java EE 6 at the moment.
We also need to have Java DB configured. GlassFish already includes a copy of Java DB in its installation folder. If you wish to learn how to configure Java DB, refer to Chapter 4, JDBC and NetBeans.
It is possible to create this recipe if an existing database schema and an EJB application exists. However, for the sake of brevity, we will use the sources from the previous recipes.
Right-click on the EJBApplication node, select New then Other then Web Services and RESTFul Web Services from Entity Class....
- For Entity Classes: On Available Entity classes, select Manufacturer, click Add, and click Next.
- For Generated Classes: Leave all the fields with their default values and click Finish.
A new dialog, REST Resources Configuration, pops-up; select the first option and click OK.
The REST resources configuration asks the user which way the RESTful resources should be accessed, presenting the user with three different options. We have chosen to use javax.ws.rs.core.Application because it is the standard in Java EE 6 and, thus, increases the portability of the application, instead of the web.xml option. The second option allows the developer to code their way through registering the resources and choosing the service path.
To take a look at the generated files, expand the service package. Two java files are present: AbstractFacade.java and ManufacturerFacadeREST.java.
Opening the ManufacturerFacadeREST.java will show that this file is actually a stateless EJB created by the IDE that is used to interface with the database and retrieve information from it.
NetBeans also automatically generates a converter for our ManufacturerResource. This converter is used for creating a resource representation from the corresponding entity instance. Those classes can be found in the converter package.
Using NetBeans to test the web services.
Now that we have created a RESTful web service, we need to know if everything is working correctly or not.
To test our web service, right-click EJBApplication and select Test RESTful Web Service. NetBeans will be launched; deploy our application in GlassFish and then point the browser to the web service.
When the Test RESTful Web Service page opens, click on the Test button on the right side.
Upon clicking Test, the test request is sent to the server. The results can be seen in the response section.
Under Tabular View, it is possible to click in the URI and get the XML response from the server.
Raw View, on the other hand, returns the entire response, as it would be handled by an application.
It is also possible to change the format in which the response is generated. Simply click on the drop-down Choose method to test from GET(application/xml) to GET(application/json) and click Test. Then click on Raw View to get a glimpse of the response.