Examples

Introduction

An example project download is provided that works both under Eclipse and via ant build. This sets up the basic framework for GWT compilation and debugging in Hosted Mode, provides a basic Restlet-powered server, and demonstrates how the compiled GWT application can be bundled into an executable server JAR.

Download Restlet GWT – Simple Example (application/force-download, 5.4 MB)

This is a simple example demonstrating some basic patterns for using Restlet and GWT. It produces an executable JAR file which depends only on core Restlet libraries (included in “lib”) to start a small Java Web server on port 8888, which you can visit to access a compiled GWT application that, in turn, talks to the Web server.

You can also run the application in GWT Hosted Mode under Eclipse by using the included SimpleExample.launch configuration; right click this and choose Run As … SimpleExample.

It is structured as an Eclipse project; you should be able to import it into your Eclipse 3.3 or better workspace. You can also run the ant build script directly to produce the executable.

You must supply your own GWT binaries (it should work for 1.7 and upper releases of GWT) ; update the Eclipse build path and/or the “gwt.sdk” property in the ant build script to point to the GWT binaries for your platform.

Zip content

Description

GWT page

You can find the source code of this page in directory “src/org/restlet/example/gwt/client”.

Once the server is running, this page can be accessed at the following URL: “http://localhost:8080/TestGwtRestlet_2_0.html” .

This page is in charge to display several sample item such image, button, etc organized in panels. All of these objects are instances of GWT classes:

// Define an image
Image img = new Image("http://code.google.com/webtoolkit/logo-185x175.png");
// Define a button
final Button button = new Button("Click me");
[...]
// Define a panel
VerticalPanel vPanel = new VerticalPanel();
// We can add style names.
vPanel.addStyleName("widePanel");
vPanel.setHorizontalAlignment(VerticalPanel.ALIGN_CENTER);
// Add image, button, tree
vPanel.add(img);
vPanel.add(button);

These class illustrates also how to add an asynchronous call with AJAX inside the final Web page. It is as simple as to use a simple Restlet client in order to request the “ping” resource located at URL ‘“http://localhost:8080/ping” :

// Add an AJAX call to the server
ClientResource r = new ClientResource("/ping");
// Set the callback object invoked when the response is received.
r.setOnResponse(new Uniform() {
    public void handle(Request request, Response response) {
        try {
            button.setText(response.getEntity().getText());
        } catch (IOException e) {
             e.printStackTrace();
        }
    }
});
r.get();

Server side

Basically, the server s responsible to serve the generated page, and to respond to asynchronous call described just above.

The generated page is served by a simple Directory Restlet from the “bin” directory when the server is run under Eclipse.

The asynchronous call is delegated to the PingResource class which inherits from the ServerRestlet Resource class. It simply answers to requests with a line of text that contains the HTTP method of the request and, if available, its challengeScheme if the user has provided credentials.

public class PingResource extends ServerResource {
    @Get("txt")
    public String toText() {
            StringBuilder sb = new StringBuilder("Restlet server alive. Method: ");
        sb.append(getRequest().getMethod());
        ChallengeResponse challengeResponse = getRequest()
                .getChallengeResponse();
        if (challengeResponse != null) {
            sb.append("/ Auth. scheme: ");
                sb.append(challengeResponse.getScheme());
        }
        return sb.toString();
    }
}