Wise ASP - How the Cookie Crumbles
Cookies are information stored on the client's machine, and are sent to the server with each request for information. The server can set or change the cookie's values, and the Response object provides an interface for this purpose. Also, the Request object provides a way to access cookies from the server.Why Use Cookies?
Why use cookies at all? We could store the same information in a database, or file of some other type, on the server's disk. In fact, it would be more flexible using a database, since it can handle data other than text.However, there will be always be an overhead assocaited with accessing an external data source on the server. Using a cookie is a very fast and convenient way of storing small amounts of information. There are limits of course. We shouldn't store more than twenty cookies for any one domain. One of the most popular uses of cookies is storing user information. You enter it once and then the server it many times with future assistance from your side. Let's look at how we can create cookies on the server. And then we will look at retrieving them from the server.
Sending Cookies to the Browser
This code adds a cookie to a client's cookie set, or changes the value of this cookie if it already exists:
Response.Cookies("name") = lastName & firstName
Please note: Any changes to cookies with the
Response object cause HTTP headers to be sent to the client,
and so they must be executed before any HTML is written.
Cookies Properties
Cookies have properties relating to their lifetime and availability. If we don't set these explicitly, any information stored in them will be lost when the broswer is closed. We need to set an expiry date, using the expires property. We can also set various other properties of a cookie, to restirct which servers can gain access to information stored in it. These other properties are domain, path and secure. Setting the domain to Request.ServerVariables("Server_name") would mean that only pages existing on your network would receive the cookie from the broswer. We can also be more specific by setting the path to "wsk". The final attribute, secure, indicates that the cookie should only be transmitted to the server over a Secure Sockets Layer connection. Here is an example of using all the properties:
Response.Cookies("name") = lastName
Response.Cookies("name") = firstName
Response.Cookies("name").Domain = Request.ServerVariables("Server_name")
Response.Cookies("name").Expires = "date + 365"
