GWT plugin for Struts

The source of this tutorial: http://cwiki.apache.org/S2PLUGINS/gwt-plugin.html

This plugin can be used to call methods on Struts actions using Google Web Toolkit (GWT):

Name	GWT Plugin
Publisher	Musachy Barroso, Sean McRae
License	Open Source (ASL2)
Version	0.2 stable
Compatibility	Struts 2.0.2+
Homepage	http://code.google.com/p/struts2gwtplugin/
Download	http://code.google.com/p/struts2gwtplugin/downloads/list

Example

Setup Action

Start by creating an action that contains the method that is going to be called. This method needs to match the signature of the service interface, but you don't need to implement the interface on the action. This method will be different from regular Struts 2 action methods in that it returns any object (that GWT can serialize), instead of a result name. If you want to call regular actions from GWT (not using GWT's RPC) go here

In this example the action "Hello" will return the string passed to it. Remember, the returned object is not the regular Struts result, it is the object that you will receive on the client side.

Example:

public class Hello {
 public String hello(String text) {
     return text;
 }
}

Write the mapping for the action

For any action mapping that is going to be called from GWT:

1. Add the map inside a package that extends "gwt-default"
2. Add the "gwt" interceptor to the mapping

Example:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

<constant name="struts.enable.DynamicMethodInvocation" value="false" />
<constant name="struts.devMode" value="true" />

<package name="example" extends="gwt-default">
<action name="Hello" class="example.Hello" method="hello">
<interceptor-ref name="gwt"/>
</action>
</package>

</struts>

GWT classes

Write the required service interface as described here. This is regular GWT stuff.

As an example of the interface:

public interface MyService extends RemoteService {
  public String hello(String s);
}

public interface MyServiceAsync {
  public void hello(String s, AsyncCallback callback);
}

And to call it:

MyServiceAsync service = (MyServiceAsync) GWT.create(MyService.class);
AsyncCallback callback = new AsyncCallback() {
  public void onSuccess(Object result) {
      Window.alert(result.toString());
  }

  public void onFailure(Throwable caught) {
      Window.alert(caught.toString());
  }
};
ServiceDefTarget endpoint = (ServiceDefTarget) service;
endpoint.setServiceEntryPoint("Hello.action");
service.hello("Hi There!", callback);

Installation

This plugin can be installed by copying the plugin jar and gwt-servlet.jar (from GWT) into your application's /WEB-INF/lib directory. No other files need to be copied or created.