Cookies
Cookies spent a year or two as a little-known feature of Netscape Navigator before becoming the focus of a raging debate on electronic privacy. Ethical and moral considerations aside, cookies allow a web server to store small amounts of data on client systems. Cookies are generally used to store basic user identification or configuration information. Because a cookie’s value can uniquely identify a client, cookies are often used for session tracking (although, as we’ll see shortly, the Servlet API provides higher-level support for this).
To create a cookie, the
server (or, more precisely, a web application running on the server)
includes a Cookie header with a specific value in
an HTTP response. The browser then transmits a similar header with
that value back to the server with subsequent requests, which are
subject to certain rules. The web application can use the cookie
value to keep track of a particular user, handle session tracking,
etc. Because cookies use a single Cookie header,
the syntax for a cookie allows for multiple name/value pairs in the
overall cookie value.
More information about the cookies is available from the original Netscape specification document at http://home.netscape.com/newsref/std/cookie_spec.html. The Internet Engineering Task Force is currently working on a standard cookie specification, defined in RFC-2109, available at http://www.cis.ohio-state.edu/cgi-bin/rfc/rfc2109.html.
The Servlet API includes a class,
javax.servlet.http.Cookie ...
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