14.1 Client-Server

A client-server relationship is the basic architecture of communication in HTTP protocol. If a direct TCP connection between a client and a server is established, the user types the Uniform Resource Identifier (URI) he or she wants to survey into the browser:

Figure 14.1: HTTP architecture

As shown in the previous figure, the client first takes the server name from the URI and with the help of DNS, translates it into the IP address (1 and 2). Then the client establishes a TCP connection with the obtained IP address of the server. The browser inputs the HTTP request into the newly created channel (3), and the server responses with an HTTP response (4) within the same TCP connection. Then, the browser displays the response to the user.

It is important that the browser displays the web pages to the user. Every web page usually consists of many objects and every object must be downloaded by a separate HTTP request from the web server. In the older versions of the HTTP protocol...