User Server Interaction
Cookies of the world wide web was originally designed as a stateess entity. A client sends a request and the server responds. Their relationship is over. The original design of www. Retrieving publicly available documents exactly fits this purpose. Today the web has other functions some are listen here.
a.Some websites need to allow access to registered clients only.
b.Websites are begins used as electronic stores that allows users to browse through the store select wanted items put them in an electronic cart and path end with a credit card.
c.Some websites are used as portals the user selects the web pages which he wants to see.
d.Some website are just advertising.
For these purpose, the cookies mechanism introduced. Cookies are more commonly referred to as web cookies tracking or just cookies are parcels of next sent by a server to a web client ( usually a browser) and then sent back unchanged by the client each time it accesses that server. Cookies are used for authenticating session tracking state maintenance and maintaining specific information about uses such as site preference or the contents of their electronic shopping carts.
Cookies technology has four components:
a.a cookie header line in the HTTP response message.
b.A cookie header line in the HTTP request message.
c.A cookie file kept on the user end system and managed by the user browser .
d.A back end database at the website.
Let go through an example of how cookies are used. Suppose Hassan who always access the web using internet explorer from his home PC contacts and e commerce site for the first time and this site uses cookies. When the request comes into the web server the web site creates a unique identification number and creates an entry in its back end database that is indexed by the identification number. The server then responds to Hassan browser including in the HTTP response a set cookie. Header which contains the identification number. For example the header lien might be: