JSF-Session scopes

Hi,

Today we will discuss about different scopes of managed bean in JSF(Java server faces).

A brief introduction about JSF and managed bean.

Java Server Faces:- A component based Java web development frame work which supports MVC model.

MVC model:-

• Model :- Backing beans,where web page components are mapped to an instance variables of a bean
• View- presentation layer
• Controller:- which will manage the navigation of web pages based on a particular output.

There are four different session scopes(Ascending) for a manged bean.

1. View/Page:- valid only for a particular page
2. Request:- valid for a particular request
3. Session:- valid for a session
4. Application:- valid for entire web application at the container(server) level.

We will explain them in more detail by below examples

JSP pages:-

• Login.jsp:- will have userName,password,login button and log out button
• userWelcome.jsp :- If userName is google the user name parameter is displayed here.This page also has links to page1.jsp and page2.jsp
• page1.jsp:- The username is forwarded to this page from login page
• page2.jsp:-The username is forwarded to this page from login page

snapshots or code for jsp pages..

Login.jsp

userWelcome.jsp

page1.jsp/page2.jsp

ManagedBean/Backing bean

• SessionMaintanence :- where session invalidation,defining scopes etc. are done

faces-config.xml :- is an xml where manged bean are registered,navigation is defined.

Control flow of application:-

Login.jsp will have user name and password,when user clicks on Login button and user name entered is google the page is forwarded to userWelcome.jsp displaying logged in user name.

In userWelcome.jsp we have liks to pag1.jsp and page2.jsp

Every page will have a logout button. The logged in userName is used in all the pages.

Code for SessionMaintanence bean:-

@ViewScoped //scope of the bean

@ManagedBean //Registering the bean as manged bean

public class SessionMaintanence implements Serializable {

private String userName; //username mapping

private String passWord;

//getter and setter methods

public String getUserName() {

return userName;

}

public void setUserName(String userName) {

this.userName = userName;

}

public String getPassWord() {

return passWord;

}

public void setPassWord(String passWord) {

this.passWord = passWord;

}

public String validate()

{

if(getUserName().equals("google"))

{

return "success";

}else

{

return "false";

}

}

//Method for session invalidatio

public String inValidate()

{

FacesContext fc=FacesContext.getCurrentInstance();

ExternalContext ec=fc.getExternalContext();

ec.invalidateSession();

return "";

}

}

1. Page/View scope:- We will enter google as username and click on login,the page is navigated to userWelcome.jsp

In the above code we have scope as viewScoped...

Now we will enter userName as google enter password and click on Login,the page is directed to userWelcome.jsp, as we can see as the bean is viewScoped the userName will not be printed in this page the out put will be

welcome

page1 page2 

Conclusion:- As the bean is view/page scoped userName is not forwarded to userWelcome.jsp the value is limited to Login.jsp page only.

2.Request scope :- Now we will change the scope to @RequestScope in SessionMaintanence and will execute the same by entering google
as user name and password
The output from the userWelcome.jsp will be like
welcome google

page1 page2 

Now we will click on page1.The output will be like

welcome to page1
[Actually here userName also should be printed]
Though the scope is request the username did not get printed,because when we click on page1 hyperlink we are sending a new request so the values stored in the earlier request will be lost
3.Session scope
We will change the scope to @SessionScoped ,will execute the same flow the output from userWelcome.jsp will be
welcome google
page1 page2 
Now we will click on page1 ,we are sending a new request as the bean is in session scoped the output from pag1.jsp will be
welcome google to page1 

Observe the differences between request and session scoped from the output from page1.jsp

welcome to page1 and welcome google to page1 

4.Application scope

This the most wider range scope at the application level for entire container/server

Lets take a scenario where we want to count the number of page hits for our page.How to implement this scenario?Which session scope we will use?

Here comes the application scope.