Tuesday, April 27, 2010

Explain the scope of JSP objects.

Scope of JSP objects:
The availability of a JSP object for use from a particular place of the application is defined as the scope of that JSP object. Every object created in a JSP page will have a scope. Object scope in JSP is segregated into four parts and they are page, request, session and application.

* page
‘page’ scope means, the JSP object can be accessed only from within the same page where it was created. The default scope for JSP objects created using tag is page. JSP implicit objects out, exception, response, pageContext, config and page have ‘page’ scope.
* request
A JSP object created using the ‘request’ scope can be accessed from any pages that serves that request. More than one page can serve a single request. The JSP object will be bound to the request object. Implicit object request has the ‘request’ scope.
* session
’session’ scope means, the JSP object is accessible from pages that belong to the same session from where it was created. The JSP object that is created using the session scope is bound to the session object. Implicit object session has the ’session’ scope.
* application
A JSP object created using the ‘application’ scope can be accessed from any pages across the application. The JSP object is bound to the application object. Implicit object application has the ‘application’ scope.

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