Nortel Networks WEB OS 212777 - Manual (Page 424)

Web OS 10.0 Application Guide
424 n Chapter 16: Persistence
212777-A, February 2002
Cookie-Based Persistence
Cookies are a mechanism for maintaining state between clients and servers. When the server
receives a client request, the server issues a cookie, or token, to the client, which the client then
sends to the server on all subsequent requests. Using cookies, the server does not require
authentication, the client IP address, or any other time-consuming mechanism to determine
that the user is the same user that sent the original request.
In the simplest case, the cookie may be just a “customer ID” assigned to the user. It may be a
token of trust, allowing the user to skip authentication while his or her cookie is valid. It may
also be a key that associates the user with additional state data that is kept on the server, such as
a shopping cart and its contents. In a more complex application, the cookie may be encoded so
that it actually contains more data than just a single key or an identification number. The
cookie may contain the user’s preferences for a site that allows their pages to be customized.
Figure 16-1 Cookie-Based Persistence: How It Works
1
USER REGISTERS TO BUY
AN ITEM
2
SWITCH COMPLETES THREE-WAY
HANDSHAKE WITH CLIENT.
- FORWARDS HTTP REQUEST TO COOKIE
SERVER
3
WEB SERVER DESIGNATED TO SERVE
COOKIES RECORDS INFORMATION AND
SENDS THE CLIENT A COOKIE
4
SWITCH RECORDS OR REWRITES
COOKIE INFORMATION BASED ON
CONFIGURATION
5
COOKIE STORED ON CLIENT
MACHINE
6
CLIENT DECIDES TO BUY AN
ITEM. THE COOKIE
INFORMATION IS SENT AS
PART OF THE HTTP
REQUEST
7
BASED ON COOKIE INFORMATION SWITCH
REDIRECTS REQUEST TO THE SAME SERVER
OR HASHES ON COOKIE VALUE