Scsong at 23:08, 11 September 2008

2008-09-11T23:08:39Z

← Older revision		Revision as of 23:08, 11 September 2008
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	Build and run the project and it should be a slightly more verbose Hello World.		Build and run the project and it should be a slightly more verbose Hello World.

	Deployment to a real Tomcat instance		===Deployment to a real Tomcat instance===

	Add the servlet to the ''web.xml'' file:		Add the servlet to the ''web.xml'' file:
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	</pre>		</pre>

	Development jar is not necessary and user jar will fail to load because it contains ''javax.servlet.Servlet=		Development jar is not necessary and user jar will fail to load because it contains ''javax.servlet.Servlet''

	For more information: [[media:gwt-tutorial-4.tar.gz\|GWT Tutorial 4]]		For more information: [[media:gwt-tutorial-4.tar.gz\|GWT Tutorial 4]]

Scsong at 23:07, 11 September 2008

2008-09-11T23:07:48Z

New page

==AJAX/RPC: Quick and Dirty==

Read the GWT docs if you want more detail.

===Create Service Interface===

Goes in the client package, must extend ''RemoteService=

<pre>
package edu.umiacs.gwt.hello.client;

import com.google.gwt.user.client.rpc.RemoteService;

public interface HelloWorldService extends RemoteService
{
public String doService(ServiceRequest request);

}
</pre>

===Serialize Custom Types===

Custom types must implement the ''IsSerializable'' marker. Class *MUST* have an *explicit* empty constructor.

<pre>
package edu.umiacs.gwt.hello.client;

import com.google.gwt.user.client.rpc.IsSerializable;

public class ServiceRequest implements IsSerializable
{
private String greeting;
private char punctuation;

public ServiceRequest(){}

public ServiceRequest(String greeting, char punctuation)
{
this.setGreeting(greeting);
this.setPunctuation(punctuation);
}

public String getGreeting(){ return greeting; }
public void setGreeting(String greeting) { this.greeting = greeting; }
public char getPunctuation(){ return punctuation; }
public void setPunctuation(char punctuation) { this.punctuation = punctuation; }
}
</pre>

===Create Async Service Interface===

Define the exact same methods the non-async interface contains but have all methods return void and append an ''AsyncCallback'' parameter to the end of each method.

<pre>
package edu.umiacs.gwt.hello.client;

import com.google.gwt.user.client.rpc.AsyncCallback;

public interface HelloWorldServiceAsync
{
public void doService(ServiceRequest request, AsyncCallback ac);
}
</pre>

===Implement the Service===

In the root package, create a package named ''service'' which will hold all server-side, non-translatable code. Create the implementation class in this package. Class must extend ''RemoteServiceServlet'' and implement the non-async service interface.

<pre>
package edu.umiacs.gwt.hello.server;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import edu.umiacs.gwt.hello.client.HelloWorldService;
import edu.umiacs.gwt.hello.client.ServiceRequest;

public class HelloWorldServiceImpl extends RemoteServiceServlet
implements HelloWorldService
{

public HelloWorldServiceImpl()
{
System.out.println("HelloWorldServiceImpl.<init>");
}

public String doService(ServiceRequest request)
{
return request.getGreeting() + " to the world" +
request.getPunctuation();
}

}
</pre>

===Register the Servlet with the Shell===

In the ''ModuleName.gwt.xml'' file, add a servlet element:

<pre>
<module>
<inherits name="com.google.gwt.user.User"/>
<entry-point class="edu.umiacs.gwt.hello.client.HelloWorldApp"/>
<servlet class="edu.umiacs.gwt.hello.server.HelloWorldServiceImpl" path="/hello-service"/>
</module>
</pre>

The path is relative to the context root.

===Invoke the service===

<pre>
package edu.umiacs.gwt.hello.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.rpc.ServiceDefTarget;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.Widget;

public class HelloWorldApp implements EntryPoint
{
Label lblSayHello = new Label();

public void onModuleLoad()
{
GWT.log("onModuleLoad()", null);

Button btnAsk = new Button("Say something");
btnAsk.addClickListener(new ClickListener()
{
public void onClick(Widget w)
{
lblSayHello.setText("...Asking Server...");
retrieveMessageFromServer();
}
});

VerticalPanel vp = new VerticalPanel();
vp.add(btnAsk);
vp.add(lblSayHello);

RootPanel root = RootPanel.get("div1");
root.add(vp);
}

private void retrieveMessageFromServer()
{
HelloWorldServiceAsync service =
(HelloWorldServiceAsync)GWT.create(HelloWorldService.class);

ServiceDefTarget endpoint = (ServiceDefTarget)service;
String moduleRelativeURL = GWT.getModuleBaseURL() + "hello-service";
endpoint.setServiceEntryPoint(moduleRelativeURL);

AsyncCallback callback = new AsyncCallback()
{
public void onSuccess(Object result)
{
String message = (String)result;
lblSayHello.setText(message);
}

public void onFailure(Throwable caught)
{
lblSayHello.setText("Error: " + caught.toString());
}
};

service.doService(new ServiceRequest("Hello", '.'), callback);
}
}
</pre>

===Ready to Run===

Build and run the project and it should be a slightly more verbose Hello World.

*Deployment to a real Tomcat instance*

Add the servlet to the ''web.xml'' file:

<pre>
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>hello-service</servlet-name>
<servlet-class>edu.umiacs.gwt.hello.server.HelloWorldServiceImpl</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hello-service</servlet-name>
<url-pattern>/hello-service</url-pattern>
</servlet-mapping>
</web-app>
</pre>

Modify the ''build.xml'' file to include the class files and the required libraries:

<pre>
<target name="-war-dist">
<war destfile="dist/hello-world.war" webxml="src/edu/umiacs/gwt/hello/web.xml">
<fileset dir="dist/hello-world"/>
<lib dir="dist/lib">
<exclude name='gwt-dev*.jar'/>
<exclude name='gwt-user.jar'/>
</lib>
<classes dir="build/classes"/>
</war>
</target>
</pre>

Development jar is not necessary and user jar will fail to load because it contains ''javax.servlet.Servlet=

For more information: [[media:gwt-tutorial-4.tar.gz|GWT Tutorial 4]]

Netbeans:NetbeansGWTRPC - Revision history

Scsong at 23:08, 11 September 2008

Scsong at 23:07, 11 September 2008