My Thoughts !

A better and updated version is maintained here (http://grprakash.googlepages.com/gwtwithejb).
In this post, I thought I'll explain how to use GWT with EJB. GWT addresses the web layer and EJB the middle layer, its natural to use both of them to have a neat J2ee app.

I assume that you know how to create EJB project and Web project with Googlipse. For the second one, I've written a post here.

If you are an advanced EJB developer and have used GWT for a while, "Use the RemoteServiceImpl as a EJB client and continue in the as usual way". If you are not, then the rest of the post is for you.

What we are trying now is to have a text box in the web page and a button. When you key in a person's name there and press the button, it will show the age of the person.

The first step is to create a Stateless Session Bean. The Remote & Home interface will look like this:

public interface AgeServiceEjb
extends EJBObject, Remote {

public int getAge(String name);
}

public interface AgeServiceHome
extends EJBHome {
public AgeService create()
throws ...;
}

public class AgeServiceBean
implements SessionBean {


//All EJB members here
public int getAge(String name){

int age;

if(name.equals("Pranni"))
age = 18; //Pranni is always 18 :-)
else if(name.equals("Bill Gates"))
age = 51;
else
age = 40; // default value

return age;
}
}

public interface AgeServiceGwt
extends RemoteService {

public int getAge(String name);

// Other members Util, SERVICE_URI etc
}

public interface AgeServiceGwtImpl
extends RemoteServiceServlet
implements AgeServiceGwt{

public int getAge(String name){
Context ctx = new InitialContext();
AgeServiceHome hme =
(AgeServiceHome)ctx.lookup("<JNDI name>");
AgeServiceEjb ageService = hme.create();
return ageService.getAge(name);
}
}

• How do I deploy the EJB in the GWT's embedded Tomcat server?

You can't. In fact you can't deploy it even on an external Tomcat. Its just a web container. You need an app server like WebLogic or JBoss

• How do I create a EAR file?

Create an EAR project and add these projects (EJB & Web) to it. Select File->Export->Export as EAR file

• Can I deploy the application in an app server and still debug in hosted mode?

Yes. Look at "Deploying to an external server" in the GWT tutorial. Its the same way.