Web Stack Series Part 2: Webserver Software

July 2, 2007 | Filed Under Technology, General

Web Part 2 of The Web Stack Explained leads us to the webserver software. Webserver software basically serves as the interface for files stored on the server. Let’s start things of with a good, but rather stuffy definition of the word “webserver” from Wikipedia:

A computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are Web pages such as HTML documents and linked objects (images, etc.).

Now, let’s break this down piece by piece:

A computer program
A webserver is a computer program, just the same as WinZip and Solitaire. Webservers can be downloaded and installed just like anything else you place on your computer. They are responsible for serving requests for websites, hence the term: web - server. Webserver software is usually run differently than the programs you are familiar with. Since your server can’t predict when someone wants to view your web page, the webserver software must be constantly listening for requests. As a result, the webserver software is started up and then left to quietly run in the background indefinitely. When a request is received, the webserver processes the request, fetches the pages and files that were requested, and sends them all back to the person doing the requesting.
HTTP Requests
HTTP stands for HyperText Transfer Protocol - but you don’t care. And quite frankly you don’t need to care. Just think of HTTP as the ether that lets computers talk to each other over the Web. Requests are messages sent by users to your webserver. Whenever someone types a URL in their web browser, they are making a request to the webserver associated with that URL. The webserver catches this request and then acts accordingly.
Clients, or Web Browsers
If “server” refers to webservers, then “client” refers to web browsers. Web browsers are the software programs used to surf the web. Microsoft Internet Explorer and Mozilla Firefox are the two most popular these days. Web browsers are translators: they translate human requests for web sites into requests that webserver software can process. When the webserver processes the request and sends back the appropriate information, the user’s web browser displays it in all its glory.
HTTP Responses
HTTP responses are what webservers send back to web browsers after a request is made. These responses typically contain the web pages, images and files that were requested by the user.
Web pages
The final pieces of the puzzle. Web pages are the files stored on the server that users request. These are typically text files full of HTML and other markup. Your web browser is designed to translate these files into the correctly formatted web pages that you view.

There are several brands of webserver software available, but the two most popular are Apache HTTP Server and Microsoft Internet Information Services server. Although the primary responsibility of the webserver software is to fetch and return the appropriate website files, there is another function: running other software required by the files themselves. This other software is typically a script engine, and we will talk about that in our next Web Stack Series installment!

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