Lesson 5: Saving User Information

Using Cookies

Cookies are a mechanism by which state can be maintained in a file on the user 's computer. This file is typically stored in a folder named cookies.


Note

Although the major Web browsers support cookies, two problems remain :

  • Cookies are not a standard feature of HTTP or other specifications. Therefore, they may not be available for all Web browsers.
  • Because cookies enable a Web server to create and edit a file on a user's computer (which is a potential security breach), both Netscape and Microsoft enable users to turn off this feature.

A cookie is like a token for a specific page that a Web server sends to a user. The user sends the cookie back to the server during each subsequent visit to that page or number of pages.

Cookies allow information to be associated with a user. You can set and get the values of cookies by using the Cookies collection.

When the Web server returns an HTTP response to a user, the response message may include a cookie. The cookie includes a description of the saved range of URLs for which that cookie is valid.

A cookie is introduced to the user by including a Set-Cookie header as part of an HTTP response. Any HTTP requests made by the user included in the specified range are accompanied by the current value of the cookie.

Creating Cookies

To set the value of cookies that your Web server sends to a user, you use the Cookies collection of the Response object. If the cookie does not already exist, Response.Cookies will create a new cookie on the user's computer.

Example

This example creates a cookie with the city set to Redmond:
 <% Response.Cookies("city")="Redmond" %> 

If you want the cookie to apply to all of the pages in your Web application, you set the Path attribute of the cookie to "/." The cookie will then be sent by the Web browser during each request for a page in your Web application.

Example

This example sets the Path attribute of the cookie.
 Response.Cookies("city").Path = "/" 

You can set other attributes for cookies, such as when the cookie should expire.

Example

This example sets the cookie's expiration date:
 Response.Cookies("Type").Expires = "July 31, 1997" 

Reading Cookies

The Web browser sends cookies to the appropriate pages in your Web application. To read the value of a cookie, use the Cookies collection of the Request object.

Example

If the HTTP request sends a cookie with the city set to Redmond, then this example code retrieves the value of Redmond:
 <%= Request.Cookies("city") %> 


Microsoft Windows Architecture Training
Microsoft Windows Architecture for Developers Training Kit
ISBN: B00007FY9D
EAN: N/A
Year: 1998
Pages: 324

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