Managing Session State Between Views in a Web Application

Overview

This use case illustrates session handling in a CAF Web-based application. It demonstrates how to manage session attributes among the views of a Web application.

The use case demonstrates session handling using a shopping cart application, which allows users to add books to a shopping cart. The Web application manages the shopping cart as a session (scope) attribute among the pages of the application; that is, the shopping cart is a managed bean in session scope.

Prerequisite Setup

Before you can follow the step-by-step instructions, the following is required:

Create a Web Application Project project in Designer.

Add two or more Web Application Views to the project. These are views that will share session information.

For the sample that illustrates the use case, the shared session information is the shopping cart information. The sample uses two views:

Default view that displays a table of books that a user can add to the shopping cart.

Billing Page view that displays the shopping cart.

Start adding Java classes, managed bean properties, and content providers that your application will require, but that do not manipulate the shared session information. (The detailed step-by-step instructions will illustrate how to work with the shared session information.)

For the sample that illustrates this use case, the following are the items that are added to the Default view in preparation for the steps described in this article.

 

Item	Description
Book class	Defines information about an individual book. Each row of the tables that are in the views contain a Book object.
BooksCategory class	Defines different categories of books, for example, children’s books or biographies.
Books Category property	A page bean property in the Default view to hold the categories defined by the BooksCategory class. The Default view will contain a Dropdown control that is bound to the Books Category property; as a result, the Dropdown control will list the categories. The user selects a category to limit the books the application displays in a table on the Default view.
Books By Category property	A page bean property in the Default view to hold Book objects of the selected category.
Books By Category content provider	A content provider in the Default view that is based on the Books By Category property. The application uses it to populate a table in the Default view.

Note: The items for the Billing Page require information shared with the Default view, which is the focus of this article. As a result, the step-by-step instructions will describe how to add these items.

Start adding user interface controls to each view in your application.

For the sample that illustrates this use case, the following are the items that are added to the Default view in preparation for the steps described in this article.

Dropdown list that contains categories that a user can select to limit the display of books in the table. This control is bound to the Books Category property.

Table that holds the books of the selected category. This table is bound to the Books By Category content provider.

Async Hidden Command control that updates the table when the user changes the Dropdown list.

Raise On Change control that causes the application to execute the Async Hidden Command control after the user changes the Dropdown list.

Button labeled “Proceed to Billing”; a user clicks this button to go to the Billing Page view, which displays the shopping cart.

Note: The items for the Billing Page require information shared with the Default view, which is the focus of this article. As a result, the step-by-step instructions will describe how to add these items.

The following shows the Default view for the sample with the prerequisite setup complete.

Basic Steps

This article describes how to work with session attributes by first working with the main view of an application (in the case of the sample, the Default view), and then referencing the attributes in the other views of the application.

Add one or more Java classes that maintain the session information that you want to share among the views of your application.

For the sample that illustrates the use case, you will add a BooksCart class that maintains information about the books a user adds to the shopping cart. The BooksCart class has methods to manipulate the contents of the shopping cart, for example:

Add a book to the shopping cart.

Return information about a book in the shopping cart.

Get all books in the shopping cart.

Remove a book from the shopping cart.

You can view this class by downloading the sample from the webMethods CAF Development Center:

http://www.ajax-softwareag.com/articles/V8WGMN/CAF_Bookshop

Add a managed bean to hold the data you want to share across views in the application. At this point, you only add this to one of the views.

For the sample, you will add a BooksCart managed bean to the Default view. To the BooksCart managed bean, add a BooksInCart property that holds information about the books in the shopping cart.

Add any user interface controls and logic to the main view that interact with the shared managed bean.

For the sample, add:

Command Button control labeled “Add to Cart”.

The action handler for the button adds a book to the shopping cart. As a result, when a user clicks the button, the selected book in the table is added to the shopping cart; the application updates the BooksInCart property of the BooksCart managed bean, which is used to maintain the list of books in the shopping cart.

Async Table control bound to the BooksInCart property to show the books in the shopping cart.

To use the same managed bean in other views of the application, from the main view of the application add a reference of the shared managed bean to other views.

For the sample, from the Default view you add a reference of the BooksCart managed bean to the Billing Page view. As a result, the BooksCart managed bean is available in the Billing Page view, as well as the BooksInCart property that was added to the BooksCart managed bean.

Add any user interface controls and logic to the other views in the application that interact with the shared managed bean.

For the sample, add the following to the Billing Page view:

BooksInCart content provider from the shared BooksInCart property that is present in the BooksCart managed bean.

Async Table control bound to the BooksInCart content provider to display the books the user added to the shopping cart.

Text control to hold the Total Bill Amount for the books in the shopping cart.

Command button labeled “Cancel” that a user clicks to return to the Default view.

Command button labeled “Remove From Cart”. The action handler for this button removes a book from the shopping cart. As a result, when a user clicks the button, the selected book in the shopping cart is removed.

Detailed Step-By-Step Instructions

1	Add logic that maintains the session information you want to share among the views.

For the sample that illustrates this use case, add the BooksCart class:

a	In Designer: File > New > Other.

b	On the Select a Wizard page, choose Java > Class and click Next.

c	On the Java Class page, do the following; then click Finish:

 

For this field...	Do this...
Source Folder	Specify the source folder of your web project (for example “project_name/src”)
Package	For the package name, type com.webmethods.caf.
Name	Type BooksCart.

d	In the Project Explorer view, open the BooksCart.java file (project_name/Java Resources: src/com.webmethods.caf/BooksCart.java).

e	Copy the contents of the BooksCart class in the CAF_BookShop sample to this BooksCart class.

You can download the Session State Management sample from the webMethods CAF Development Center.

http://www.ajax-softwareag.com/articles/V8WGMN/CAF_BookShop.zip

2	Open the main view of the application.

For the sample, open the Default view.

3	With the main view open in the editor, add a managed bean to hold the data that you want to share across the views.

For the sample, add the BooksCart managed bean to the Default view, which the application will use to maintain the list of books in the shopping cart:

a	From the Bindings view, right-click Managed Beans > default (the view's managed bean), and select New > Managed Bean.

b	Perform the following on the Managed Bean page; then click Next.

 

For this field...	Do this...
Managed Bean Name	Type BooksCart.
Managed Bean Scope	Select session. This indicates that the application is to maintain this managed bean for the entire session.

c	Set the following on the Java Type page.

 

For this field...	Type this...
Package	com.webmethods.caf
Superclass	com.webmethods.caf.faces.bean.BaseFacesSessionBean

d	Click Finish.

4	Add properties to the shared managed bean that will hold the information you want to share with other views.