What are the different scopes in JSP?

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One of the most powerful features of JSP is that a JSP page can access, create, and modify data objects on the server. You can then make these objects visible to JSP pages. When an object is created, it defines or defaults to a given scope. The container creates some of these objects, and the JSP designer creates others.

The scope of an object describes how widely it's available and who has access to it. For example, if an object is defined to have page scope, then it's available only for the duration of the current request on that page before being destroyed by the container. In this case, only the current page has access to this data, and no one else can read it. At the other end of the scale, if an object has application scope, then any page may use the data because it lasts for the duration of the application, which means until the container is switched off.

Page Scope

Objects with page scope are accessible only within the page in which they're created. The data is valid only during the processing of the current response; once the response is sent back to the browser, the data is no longer valid. If the request is forwarded to another page or the browser makes another request as a result of a redirect, the data is also lost.

//Example of JSP Page Scope
<jsp:useBean id="employee" class="EmployeeBean" scope="page" />

Request Scope

Objects with request scope are accessible from pages processing the same request in which they were created. Once the container has processed the request, the data is released. Even if the request is forwarded to another page, the data is still available though not if a redirect is required.

//Example of JSP Request Scope
<jsp:useBean id="employee" class="EmployeeBean" scope="request" />

Session Scope

Objects with session scope are accessible from pages processing requests that are in the same session as the one in which they were created. A session is the time users spend using the application, which ends when they close their browser, when they go to another Web site, or when the application designer wants (after a logout, for instance). So, for example, when users log in, their username could be stored in the session and displayed on every page they access. This data lasts until they leave the Web site or log out.

//Example of JSP Session Scope
<jsp:useBean id="employee" class="EmployeeBean" scope="session" />

Application Scope

Objects with application scope are accessible from JSP pages that reside in the same application. This creates a global object that's available to all pages.

Application scope uses a single namespace, which means all your pages should be careful not to duplicate the names of application scope objects or change the values when they're likely to be read by another page (this is called thread safety). Application scope variables are typically created and populated when an application starts and then used as read-only for the rest of the application.

//Example of JSP Application Scope
<jsp:useBean id="employee" class="EmployeeBean" scope="application" />

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Comments(12)


1. View Comment

Precise information in the article, however it would be very nice if you could have just mentioned a line or two showing how to declare variables of each scope.

Thanks,
Ketan


View Tutorial          By: Ketan at 2009-06-23 05:07:39
2. View Comment

very useful article. every jsp resource will get good knowledge from this.

View Tutorial          By: pechirani at 2011-06-29 04:00:49
3. View Comment

Excellent information in simple language. Its worthy to bookmark this site.

View Tutorial          By: Rishi at 2011-11-04 05:03:24
4. View Comment

Excellent information reg the scopes of jsp , please elaborate more with simple example or how to use these scopes.

View Tutorial          By: venkateshwarreddy suravaram at 2012-01-09 08:34:23
5. View Comment

This is very much useful to me to complete my assignment..

thanks


View Tutorial          By: Eva Jhonson at 2012-09-30 16:44:08
6. View Comment

what is differences between application scope and session scope in a session time?

View Tutorial          By: suresh at 2013-05-13 13:03:12
7. View Comment

Great article! Simple and precise. Thanks!

View Tutorial          By: dz at 2014-10-06 04:36:56
8. View Comment

Excellent information

View Tutorial          By: mahesh at 2014-10-18 06:07:35
9. View Comment

Very precisely and simply explained.

View Tutorial          By: Deepak at 2015-01-05 08:37:01
10. View Comment

Great Job

View Tutorial          By: Niteen Dhule at 2015-02-09 06:37:03
11. View Comment

thanks! it helped!

View Tutorial          By: shgy at 2015-03-17 07:42:40
12. View Comment

Very useful n understandable. More understandable if u give program example .

View Tutorial          By: Kiran at 2015-08-27 06:13:00

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