Page 291 - DCAP408_WEB_PROGRAMMING

Unit 13: ASP Cookies and Caching

The term cookies has no special significance. It is just as name. When a user requests a page, an Notes
HTTP request is sent to the server. The request includes a header that defines several pieces of
information, including the page being requested. The server returns an HTTP response that also
includes a header.

Notes The header contains information about the document being returned, including its
MIME type.
These headers all contain one or more fields of information in a basic format.
FieldName: Information
Cookie information is shared between the client browser and a server using fields in the HTTP
headers. When the user requests a page for the first time, a cookie (or more than one cookie) can be
stored in the browser by a set-cookie entry in the header of the response from the server. The set-cookie
field includes the information to be stored in the cookie along with several optional pieces of information,
including an expiry date, path, and server information and if the cookie requires security.

Then, when the user requests a page in the future, if a matching cookie is found among all the
stored cookies, the browser sends a cookie field to the server in a request header. The header
will contain the information stored in that cookie.

Did u know? How Cookie use the syntax?
The set-cookie and cookie fields use syntax to transfer significant information between
client and server.

13.2.1 Setting a Cookie

Syntax

Set-cookie: NAME=value; EXPIRES=date; PATH=path; DOMAIN=domain; SECURE
The NAME=value is the only required piece of information that must be included in the
set-cookie field. All other entries are optional.
Name Description
NAME=value Specifies the name of the cookie.
EXPIRES=date Specifies the expiry date of the cookie. After this date the cookie will no longer
be stored by the client or sent to the server. DATE takes the form WDY,
DD-MON-YY HH:MM:SS GMT. By default, the value of expires is set to the
end of current Navigator session.
PATH=path Specifies the path portion of the URLs for which the cookie is valid. If the URL
matches both the PATH and the DOMAIN, then the cookie is sent to the server
in the request header. If left unset, the value of the PATH is the same as the
document that set the cookie.
DOMAIN=domain Specifies the domain portion of the URLs for which the cookie is valid. The
default value for this attributes is the domain of the current document setting
the cookie.
SECURE Specifies that the cookie should only be transmitted over a secure link (i.e.,
HTTP servers using SSL protocol known as HTTPS server).

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