Lecture 6 - Applications #3.2: HTTP

Cookies

Cookies are an extension to HTTP, originally developed at Netscape. In general, a server "sets" a cookie by sending an additional response header, thus (eg)

HTTP/1.0 200 OK
Set-cookie: myname=myvalue
....etc...

A browser which is "cookie-enabled" will normally^[1] store this name/value pair, and future requests to the same server will contain an additional request header, thus:

GET /somefile.html HTTP/1.0
Cookie: myname=myvalue
....etc...

Cookies are extensively used in Web session management, which is discussed later in the unit.

^[1] In fact, cookie operation is rather more complex than we discuss here -- for example, the "Set-cookie: " header can take several additional parameters (which affect how the cookie is interpreted), and the behaviour of browsers with respect to cookies can be changed by the end-user.

Lecture 06: Applications #3.2: HTTP

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