Using Window Scope

Added by Carlo Guglielmin, last edited by Brad Kroeger on Dec 10, 2010  (view change)
Table of Contents

Using Window Scope Tutorial

Window Scope is a custom scope added by ICEfaces 2 to JSF 2. The purpose of this scope is to fill the niche between ViewScoped and SessionScoped by providing a slightly longer object lifespan than ViewScoped, but without the overhead of SessionScoped.

This tutorial assumes the reader has an understanding of JSF and ICEfaces and creating and working with projects related to those technologies. The focus is not to teach those basics, but instead to learn more about Window Scope.

The goal of this tutorial is to create a basic ICEfaces 2 project and examine the differences between View, Window, and Session scoped beans. The example will contain two basic pages that are navigated between, and some output information about our various scopes so we can see when a bean is created and destroyed.

Here is the entire list of steps worked through during this tutorial:

  1. Make the windowScope Project
  2. Add ICEfaces
  3. Create 3 Beans with Different Scopes
  4. Create PageController.java
  5. Create Two Pages
  6. Deploy and Test the Application

Development Tools Used

The following tools were used to create the project.

1. Make the windowScope Project

  • Using Eclipse create a new Dynamic Web Project called windowScope** Target runtime: Apache Tomcat v7.0
    • Dynamic web module version: 3.0
    • Configuration: JavaServer Faces v2.0 Project (Mojarra)

2. Add ICEfaces

Add the icefaces.jar to your project from the ICEfaces 2 bundle. This can be added to the project through a custom User Library or by putting it into windowScope/WEB-INF/lib/. The approach doesn't matter as long as the jar is included in the deployed war file.

3. Create 3 Beans with Different Scopes

We will now create a Window Scope, ViewScoped, and SessionScoped bean. Aside from the naming and scope annotation these beans are exactly the same. Each will track a Timestamp value of when they were created. This will help us determine when a bean was re-created as part of the JSF lifecycle.

3a. Create WindowBean.java

Create a new Java class file called WindowBean in the package org.icefaces.tutorial.windowscope.beans and paste the code below:

WindowBean.java
package org.icefaces.tutorial.windowscope.beans;

import java.io.Serializable;
import java.sql.Timestamp;

import javax.faces.bean.CustomScoped;
import javax.faces.bean.ManagedBean;

@ManagedBean(name="windowBean")
@CustomScoped(value = "#{window}")
public class WindowBean implements Serializable {
	private Timestamp created;

	public WindowBean() {
		created = new Timestamp(System.currentTimeMillis());
	}

	public Timestamp getCreated() {
		return created;
	}

	public void setCreated(Timestamp created) {
		this.created = created;
	}
}

The custom ICEfaces 2 Window Scope is used by this class. As the scope is custom, the JSF annotation javax.faces.bean.CustomScoped is used, with a value of #{window}. This will declare the bean as Window Scope.

3b. Create ViewBean.java

Create a new Java class file called ViewBean in the package org.icefaces.tutorial.windowscope.beans and paste the code below:

ViewBean.java
package org.icefaces.tutorial.windowscope.beans;

import java.io.Serializable;
import java.sql.Timestamp;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;

@ManagedBean(name="viewBean")
@ViewScoped
public class ViewBean implements Serializable {
	private Timestamp created;

	public ViewBean() {
		created = new Timestamp(System.currentTimeMillis());
	}

	public Timestamp getCreated() {
		return created;
	}

	public void setCreated(Timestamp created) {
		this.created = created;
	}
}

3c. Create SessionBean.java

Create a new Java class file called SessionBean in the package org.icefaces.tutorial.windowscope.beans and paste the code below:

SessionBean.java
package org.icefaces.tutorial.windowscope.beans;

import java.io.Serializable;
import java.sql.Timestamp;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

@ManagedBean(name="sessionBean")
@SessionScoped
public class SessionBean implements Serializable {
	private Timestamp created;

	public SessionBean() {
		created = new Timestamp(System.currentTimeMillis());
	}

	public Timestamp getCreated() {
		return created;
	}

	public void setCreated(Timestamp created) {
		this.created = created;
	}
}

4. Create PageController.java

Create a new Java class file called PageController in the package org.icefaces.tutorial.windowscope.controller and paste the code below:

PageController.java
package org.icefaces.tutorial.windowscope.controller;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.event.ActionEvent;

@ManagedBean(name="pageController")
@SessionScoped
public class PageController implements Serializable {
	public String navigatePage1() {
		System.out.println("Redirect to Page 1");

		return "page1";
	}

	public String navigatePage2() {
		System.out.println("Redirect to Page 2");

		return "page2";
	}

	public String action() {
		System.out.println("Action Fired");

		return null;
	}

	public void actionListener(ActionEvent event) {
		System.out.println("ActionListener Fired");
	}
}

This is a basic page backing bean that allows our tutorial application to simulate a few common use cases. The class provides two methods for navigation (between our two basic pages, which will be created next). The class also has a basic action and actionListener. By triggering each of these methods we will be able to see how Window Scope responds in comparison to ViewScoped and SessionScoped.

5. Create Two Pages

We will now create two basic pages called page1.xhtml and page2.xhtml. Both pages are very similar except for the naming and which redirect methods (from PageController.java) they use.

5a. Create page1.xhtml

Create a new page called page1.xhtml and paste the code below:

page1.xhtml
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core">
<h:head>
	<title>Window Scope - Page 1</title>
</h:head>
<h:body>
	<h2>Page 1</h2>
	<h:panelGrid columns="2">
		<h:outputLabel for="viewBean" value="View Bean:"  style="font-weight: bold;"/>
		<h:outputText id="viewBean" value="#{viewBean} created #{viewBean.created}"/>

		<h:outputLabel for="windowBean" value="Window Bean:" style="font-weight: bold;"/>
		<h:outputText id="windowBean" value="#{windowBean} created #{windowBean.created}"/>

		<h:outputLabel for="sessionBean" value="Session Bean:" style="font-weight: bold;"/>
		<h:outputText id="sessionBean" value="#{sessionBean} created #{sessionBean.created}"/>
	</h:panelGrid>

	<h:form>
		<h:panelGrid columns="4">
			<h:commandButton value="Redirect to Page 2" action="#{pageController.navigatePage2}"/>
			<h:commandButton value="Refresh Page" 
                                         action="#{pageController.navigatePage1}"/>
			<h:commandButton value="Use an Action" 
                                         action="#{pageController.action}"/>
			<h:commandButton value="Use an Action Listener" 
                                         actionListener="#{pageController.actionListener}"/>
		</h:panelGrid>
	</h:form>
</h:body>
</html>

5b. Create page2.xhtml

Create a new page called page2.xhtml and paste the code below:

page2.xhtml
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core">
<h:head>
	<title>Window Scope - Page 2</title>
</h:head>
<h:body>
	<h2>Page 2</h2>
	<h:panelGrid columns="2">
		<h:outputLabel for="viewBean" value="View Bean:"  style="font-weight: bold;"/>
		<h:outputText id="viewBean" value="#{viewBean} created #{viewBean.created}"/>

		<h:outputLabel for="windowBean" value="Window Bean:" style="font-weight: bold;"/>
		<h:outputText id="windowBean" value="#{windowBean} created #{windowBean.created}"/>

		<h:outputLabel for="sessionBean" value="Session Bean:" style="font-weight: bold;"/>
		<h:outputText id="sessionBean" value="#{sessionBean} created #{sessionBean.created}"/>
	</h:panelGrid>

	<h:form>
		<h:panelGrid columns="4">
			<h:commandButton value="Redirect to Page 1" action="#{pageController.navigatePage1}"/>
			<h:commandButton value="Refresh Page" 
                                         action="#{pageController.navigatePage2}"/>
			<h:commandButton value="Use an Action" 
                                         action="#{pageController.action}"/>
			<h:commandButton value="Use an Action Listener" 
                                         actionListener="#{pageController.actionListener}"/>
		</h:panelGrid>
	</h:form>
</h:body>
</html>

6. Deploy and Test the Application

Now that the application is setup we can build and deploy it and begin testing.

There are several use cases that demonstrate the difference between the custom Window Scope and the standard JSF 2 scopes. Open a web browser and try the following:

  • Click "Redirect to Page 1". Notice the ViewScoped bean is re-created, but Window and Session scope maintain their state.
  • Click "Refresh Page". Notice the ViewScoped bean is re-created, but Window and Session scope maintain their state.
  • Manually refresh or reload the web browser. A similar outcome as the "Refresh Page" button occurs.
  • Click "Use an Action" and "Use an Action Listener". All beans maintain their state through the processing of those buttons.
  • Open a second tab or window in the web browser. Notice new ViewScope and Window Scope beans are created, but the Session scope bean is still in scope.

As you can see, Window Scope lives longer than ViewScoped, but not quite as long as SessionScoped. Therefore this custom scope is a perfect candidate for page level backing beans. Using Window Scope instead of ViewScoped can help with user friendliness (as values aren't reset as often) without the memory footprint and overhead of SessionScoped.

Tutorial Source Code Downloads

Example Source Notes
Window Scope project windowScope source code Basic example project demonstrating how to use the custom ICEfaces 2 Window Scope.
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