Lesson 4: Expose the RPC adapter service

In this lesson, you learn how to create the RPC adapter service that returns a JSON response. The Remote Procedure Call (RPC) adapter is the IBM implementation of web-remoting.

Procedure

Expose the RPC adapter service:
1. In the Page Data view (Window > Show View > Page Data), click the Services tab.
2. Right-click RPC Adapter and select Expose RPC Adapter Service to open the Expose RPC Adapter Service window. If the RPC Adapter option is unavailable in the Page Data view, open the ShowMovies.html file, and then click the Page Data view.
3. In the POJO Class field, click Browse to open the Select a Java class to expose window.
4. In the Select entries field, type MovieService.
5. In the Matching items list, click MovieService - web2, and then click OK.
6. In the Methods list, click getMovieList(), and then click Next. The URL that is displayed calls your getMovieList method when it is started:
7. Click Finish.
  The RPC adapter service is created in the Page Data view.
  
  The RPC adapter configuration file, RpcAdapterConfig.xml, is created.
  The RPC adapter configuration editor shows the exposed getMovieList() method.
By default, the RPC adapter is configured to return all service invocations as JSON. To see how the RPC adapter works, start the service that you exposed in a web browser.
Test the RPC adapter service:
1. In the Page Data view, click the Services tab.
2. Expand RPC Adapter.
3. Right-click the getMovieList() method, and then select Run As > Run on Server.
4. In the servers list, select WebSphere Application Server v8.0, and then click Finish. The RPC service URL opens and returns the .json file.
5. A browser window opens asking you how to handle the getMovieList file. Save the file.
6. Open the file in a text editor.
```
{"result":[{"actor":"Vivien Leigh","title":"Gone with the Wind","director":"Victor Fleming","description":"Going with the wind"},{"actor":"Michael J Fox","title":"Back To The Future","director":"Robert Zemeckis","description":"Going back to the future"},{"actor":"Harrison Ford","title":"Star Wars","director":"George Lucas","description":"Wars in the stars"}]}
```
  The movie list is serialized as JSON.

What to do next

Tip: The RPC adapter shows all of the services and methods that are currently exposed. With the server running, open a web browser and type the following URL into the location bar:

http://localhost:<port>/MyMovieProject/RPCAdapter/httprpc/

The browser shows the exposed services as a table:

When you click a service, the individual methods of the service are listed:

Learn more about the RPC Adapter

Web-remoting is a pattern that provides support for JavaScript or client-side code to directly start server-side logic. Using this pattern, you can start Java™ methods from JavaScript. The invocation is performed with a JSON-RPC call. The most common usage is asynchronous calls with XmlHttpRequest. Data is transferred between the server and client in JavaScript Object Notation (JSON) format. Therefore, this pattern is essentially a form of JSON web services.

The IBM® implementation for web-remoting is known as the Remote Procedure Call (RPC) adapter for IBM. The RPC adapter is designed to help developers quickly create command-based services in a manner that complements programming styles for Ajax applications and other lightweight clients. Implemented as a generic servlet, the RPC adapter provides an HTTP interface to registered JavaBeans.

The RPC adapter provides an HTTP interface to registered JavaBeans. It deserializes the input and calls the corresponding method in the JavaBeans. It serializes the output from the JavaBeans to JSON/XML format.

The RPC adapter currently supports two RPC protocols:

HTTP RPC, which encodes RPC invocations as URLs with query parameters, for HTTP GET, or form parameters, for HTTP POST.
JSON-RPC, supports the SMD service descriptor employed by the Dojo dojo.rpc.JsonService API.

The Remote Procedure Call (RPC) adapter provides a mechanism for exposing server-side Java objects to AJAX-based user interfaces.

Lesson checkpoint

You created the RPC adapter service that returns a JSON response.

You learned:

How to use the Page Data view to expose the RPC adapter service.
How the RPC adapter exposes server-side Java objects to AJAX-based user interfaces.

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