Maintaining Sessions

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Maintaining Sessions


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HTTP Protocol

HTTP is called as a stateless protocol

because each command is request is

executed independently, without any

knowledge of the requests that were

executed before it.


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HTTP Request Methods:

GET Method: The Get method is used to getting

the data from the server. Get method appends

the parameters passed as query string to a URL,

in the form of key- value pairs. POST Method: The post method is used for

sending data to the server. In post method the

query string is appended along the request

object, they do not get appended in the URL, soparameters transfer in hidden form
http://www.roseindia.net/jsp/jspsession/HttpProtocol.shtmlhttp://www.roseindia.net/jsp/jspsession/HttpProtocol.shtml


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HTTP Request Methods:

HEAD Method: When a user wants to know

about the headers, like MIME types, charset,

Content- Length then we use Head method.

With this no body content is returned. TRACE Method: Trace on the jsp resource

returns the content of the resource. Asks for a

loopback of the request message, so that the

use can see what is being recieved on the otherside


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Http protocol is not reliable when we are doing

any type of transactions or any other related

work where persistence of the information is

necessary. To remove these obstacles we usesession management. In session management

whenever a request comes for any resource, a

unique token is generated by the serverand

transmitted to the client by the response objectand stored on the client machine as a cookie.
http://www.roseindia.net/jsp/jspsession/SessionManagement.shtmlhttp://www.roseindia.net/jsp/jspsession/SessionManagement.shtml


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Session IDs are used to uniquely identify aclient browser, while the server sideprocesses are used to associate the

session ID with a level of access. Thus,once a client has successfullyauthenticated to the web applicatiion, thesession ID can be used as a stored

authentication voucher so that the clientdoes not have to retype their logininformation with each page request


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Session management can be achieved by

using the following thing: Cookies: cookies are small bits of textual information

that a web server sends to a browser and that browsersreturns the cookie when it visits the same site again. Incookie the information is stored in the form of a name,value pair. By default the cookie is generated. If the user

doesn't want to use cookies then it can disable them. URL rewriting: In URL rewriting we append some extra

information on the end of each URL that identifies thesession. This URL rewriting can be used where a cookieis disabled. It is a good practice to use URL rewriting. In

this session ID information is embedded in the URL,which is recieved by the application through Http GETrequests when the client clicks on the links embeddedwith a page.


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Hidden form fields: In hidden form fields thehtml entry will be like this : . This means that

when you submit the form, the specified nameand value will be get included in get or postmethod. In this session ID information would beembedded within the form as a hidden field andsubmitted with the Http POST command.

In JSP we have been provided a implicit objectsession so we don't need to create a object ofsession explicitly as we do in Servlets. In Jsp thesession is by default true. The session is definedinside the directive . If we don't declare it inside the

jsp page then session will be available to thepage, as it is default by true.
http://www.roseindia.net/jsp/jspsession/SessionManagement.shtmlhttp://www.roseindia.net/jsp/jspsession/SessionManagement.shtml


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URLRewriting

URLRewriting can be used in place where we don'twant to use cookies. It is used to maintain the session.Whenever the browser sends a request then it is alwaysinterpreted as a new request because http protocol is a

stateless protocol as it is not persistent. Whenever wewant that out request object to stay alive till we decide toend the request object then, there we use the concept ofsession tracking

URLRewriting can be used where we the cookies are

disabled. Its a good practice to use URL Rewriting. InURLRewriting a string is appended


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Hidden Form Fields

Hidden form field is used to maintain the

session. It is one of the way to maintain the

session. In hidden form fields the html entry will

be like this : . This means that when you

submit the form, the specified name and value

will be get included in get or post method. In this

session ID information would be embeddedwithin the form as a hidden field and submitted

with the http post command.


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Documents

Maintaining Sessions