Server side v client side

When developing a web site, it is sometimes referred to as having a client-server architecture. This means that there are two computers involved. The first is the client computer which the end user is accessing, or requesting a web page to be delivered to. The second is the server computer which has on its hard disk the webpage files. The user requests these web pages to be sent from the server to the client, so that they can be viewed.

In web site development it is vital that the developer understands this relationship between client and server. It is also important for the developer to understand the process involved in requesting a webpage.

A webpage is viewed by the user on their own computer. The user is referred to as the client and their computer is the client computer. A webpage is displayed using a special application called a webpage browser or browser for short. The browser understands the codes inside the webpage and displays the page as directed by these codes. In most cases these codes are HTLM, but they also can be JavaScript, CSS, flash, etc.

When the client requests a web page, they simple type in the address of that page, e.g.

http://www.google.com/

This request is sent to the web sever which has this address and then the server will send this page back to the client.

This webpage is normally a simple file which the web server opens, reads and then sends the contents of this file to the client. Normally this would be simple HTML codes.

In the early phase of webpage development, these HTML codes were all there was to define the layout of the webpage. If the page needed modifying, then the developer would have to made the change and the put the new updated webpage on the web sever ready for viewing. Initial that was sufficient to display information. As commercial companies became aware of the opportunities of using web pages then just displaying information was not sufficient, they wanted their web pages to be more interactive, more dynamic. This paved the way for CGI.