Adding an authentification system in a deployed Roo/Gwt project - google-app-engine

Question

I deployed recently a Roo/Gwt project on Google App Engine.
I spent a couple of hours but couldn't find a tutorial that shows, step by step, how can we add n authentification system (withe the Federated Login Api).
I found this very good article that provides some helpful code :
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.appengine.api.users.User;
import com.google.appengine.api.users.UserService;
import com.google.appengine.api.users.UserServiceFactory;
#SuppressWarnings("serial")
public class OpenIdDemoServlet extends HttpServlet {
private static final Map<String, String> openIdProviders;
static {
openIdProviders = new HashMap<String, String>();
openIdProviders.put("Google", "google.com/accounts/o8/id");
openIdProviders.put("Yahoo", "yahoo.com");
openIdProviders.put("MySpace", "myspace.com");
openIdProviders.put("AOL", "aol.com");
openIdProviders.put("MyOpenId.com", "myopenid.com");
}
#Override
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser(); // or req.getUserPrincipal()
Set<String> attributes = new HashSet();
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
if (user != null) {
out.println("Hello <i>" + user.getNickname() + "</i>!");
out.println("[<a href=\""
+ userService.createLogoutURL(req.getRequestURI())
+ "\">sign out</a>]");
} else {
out.println("Hello world! Sign in at: ");
for (String providerName : openIdProviders.keySet()) {
String providerUrl = openIdProviders.get(providerName);
String loginUrl = userService.createLoginURL(req
.getRequestURI(), null, providerUrl, attributes);
out.println("[" + providerName + "] ");
}
}
}
}
How can I setup this authentification module? Where should I put this code because there is no "main.java" file?
Thank you very much,
Regards

Answer 1

This is in progress to be implemented for GWT 2.1/Roo 1.1.0. See this for more details https://jira.springsource.org/browse/ROO-1003
If you can't wait, check the Spring Security in Google App Engine article, at http://blog.springsource.com/2010/08/02/spring-security-in-google-app-engine/
That approach is not supported by Roo though (so once you change the generated code, it will be harder, but still possible, to continue using Roo)