1. JSP Implicit Objects
CS 422
Dick Steflik

2. Implicit Objects Objects created by the servlet container application
session
request
response
exception
out
Config
pageContext
page

3. Application Object
Used to share data between all of the pages that make up an application
All users share the Application Object
Can be accessed from any JSP in the application via the ServletContext
javax.servlet.http.ServletContext

4. Application Object Methods
getAttribute(String name)
getAttributeNames
setAttribute(String objName, Object object)
removeAttribute(String objName)
getMajorVersion()
getMinorVersion()
getServerInfo()
getInitParameter(String name)
getInitParameterNames
getResourceAsStream(Path)
log(Message)

5. Sessions
A session is a concept that represents a series of HTTP requests and responses between a specific browser and a specific server.
Sessions are managed by the server
Created by the server when the first request is received from a browser on a new host the server starts the session and assigns it an ID.
The ID is sent to the browser as a cookie and remembered by the server

6. Sessions (more)
The server creates a Session object that contains the attributes:
Creation Time ID
Last Time Accessed
Maximum Inactive Time allowed

7. HTTPSession Interface
getAttribute() – returns the object associated with the specified key string
getAttributeNames() – returns an enumeration of the key strings in the session
getCreationTime() – returns the time the session was created; millsecs past midnight since Jan 1, 1970 GMT
getID() – returns the session ID as a string
getLastAccessedTime() – returns thelast time the client sent a request for this session
getMaxInactiveInterval() – returns the maximun amount of time that the servlet container between client requests before timing out the session
setAttribute() – associates an object with a key string in the session
removeAttribute() – remove an attribute from the session
setMaxInactiveInterval() – set the time in seconds allowed between client requests
isNew() – true if a new session, false otherwise

8. request Object Javax.servlet. http.httpservletrequest.
The object request is of type Javax.servlet.http.httpservletrequest.
This denotes the data included with the HTTP Request.
The client makes a request that is then passed to the server.
The requested object is used to take the value from client’s web browser and pass it to the server.
This is performed using HTTP request like headers, cookies and arguments.

9. response Object Javax.servlet.http.HttpServletResponse
The HTTP Response data.
The result or the information that fulfills an Http request
The object response is of type javax.servlet.http. >httpservletresponse. Generally, the object response is used with cookies. The response object is used to build the HTTP response header

10. pageContext Object Javax.servlet.jsp.pagecontext
Used to access page attributes and also to access all the namespaces associated with a JSP page.

11. Out Object The Output stream in the context of page.
The class or the interface name of the Out object is jsp.JspWriter.
The Out object is written: Javax.servlet.jsp.JspWriter

12. config Object
This is used to get information regarding the Servlet configuration
The class or the interface name of the Config object is ServletConfig.
The object Config is written Javax.servlet.http.ServletConfig

13. page Object The Page object denotes the JSP page
Used for calling any instance of a Page's servlet.
The class or the interface name of the Page object is jsp.HttpJspPage.
The Page object is written: Java.lang.Object

14. Passing Values from Page to Page
Put values in the session object
Put the values in the application object
Put values at the end of the URL