At one time or the other, you may have used or heard such expressions as “Downloading file from server”, “server is slow”, “Authentication required for server access”, and so on. These are everyday expressions used in the present Information Age. Now let us take a closer look at what a server really is, with emphasis on the type of server that makes it possible for access to the Information Superhighway – the Internet, known as Web Servers, as well as what actually happens when an internet user tries to access a website via a Web Browser by sending a (Hyper-Text Transfer Protocol) HTTP request to the web server.
WHAT IS A SERVER?
A server is basically a computer program that serves some sort of content to a client using a specified protocol. The term server also refers to the computer or virtual machine running the server program, which in fact is the most common use and understanding of the term. Today, most enterprise organisations with computer network infrastructure do host their servers internally, running services such as Web, Mail, Directory service (e.g. Microsoft Active Directory), Domain Name Resolution (DNS), Dynamic Host Configuration Protocol (DHCP), File services and so on.
WEB SERVER
A Web Server is a computer program that serves content (web pages) to clients, using a common protocol known as the Hyper-Text Transfer Protocol (HTTP). In order to have access to a web server to view contents of a website, a client software known as Web Browser is used.
WEB BROWSER
Client application software used to communicate with a web server in order to display the contents of a website, using the Hypertext Transfer Protocol (HTTP). There are several browsers such as the popular and open source Mozilla Firefox browser (my favourite browser), Internet Explorer, Chrome, Safari, Opera, etc.
HOW THE WEB SERVER INTERACTS WITH THE WEB BROWSER
When an internet user types a website address, otherwise known as Uniform Resource Locator (URL), e.g. www.it-cruisers.blogspot.com on the browser address bar, an “HTTP request” is constructed and forwarded to the appropriate destination server, which responds accordingly via an “HTTP response”. This response is then formatted by the browser and presented in a user-friendly view, which could be the website homepage. Below is a graphical illustration;
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| Web Server/Browser interaction |
A SIMPLE HTTP (WEB) REQUEST FROM A WEB BROWSER TO A WEB SERVER
The general format for an HTTP request sent from a web browser to a web server is as shown;
GET: /path/file.html
Example:
GET: /ossy.tony/notifications
COMMON WEB SERVER STATUS CODES/ERROR MESSAGES
Certain useful messages are generated in the form of status codes by web browsers/servers in the course of their interaction. Here are the most commonly encountered status codes and their meanings;
Ø 404 – “Not Found”
Ø 400 – “Bad Request”
Ø 503 – “Service Unavailable”
Ø 502 – “Bad Gateway”
Since the World Wide Web (WWW) has become the most widely used resource on the internet, and gaining popularity by the day even in this era of social networking, the importance of familiarity with web server/browser interaction cannot be over-emphasized.
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