Learning Resources
Lesson
Hypertext Transport Protocol Servers, commonly referred to as Web Servers, are programs which generally reside on a server (a hardware server running a server operating system). Versions are available which can be run on any computer. When the term web server is used below it refers to the software.
Web servers reside on a computer and listen for requests from web browsers (Internet Explorer, Netscape, Mozilla). When a request comes in, it decides how to deal with it. Because it is a program, it relies on the operating system for file services, security protocols, network connections, and a host of other services. Depending on the request, it will find the file and send a reply to the web browser. Web sites have a folder and file organization structure, with hyperlinks in the files defining the path to the linked pages. The web server uses these paths to find the web page. If the web is database driven, the web server communicates with the database using scripts and rules defined by the database designer.
The contents of a web site can all be in one main folder on the machine with the web server, or they can be placed on different hard drives on different computers at different locations. The web server manages the files so that the file location is irrelevant to the person browsing the web site.
The two most common web server applications are Apache Web Server and Internet Information Server. Apache is available for Unix/Linux and for Windows. It can be run on a designated server or on a workstation. Because of its widespread use as the dominant web server application on the internet, it is generally run on dedicated servers. STEM~Net runs Apache. Internet Information Server (IIS) is a Microsoft application that runs on windows platforms. The internet implementation is predominantly on dedicated Windows servers (Windows 2000 server, Windows 2003 Server). The workstation version only runs on Windows 2000 or XP Pro. It is limited to 10 concurrent browser connections. Mac computers can also run Apache server.
While these are the dominant web servers, they are not the only ones available. Eleven different web server applications that can run on most versions of Windows are available on TUCOWS, for example.
Web servers respond to the address given by the browser when it makes a request. The address
http://www.cnn.com/2003/US/West/10/25/california.wildfire/index.html
is broken into 3 parts
http://
identifies it as a hypertext transport protocol request
www.cnn.com
identifies it as a server at CNN, and
2003/US/West/10/25/california.wildfire/index.html
gives the path from the default web site folder to the actual file (index.html).
By parsing the address, the web browser knows what the request is, where to find the file, and how to send the response.
Web servers generally use port 80
For Additional Information
for additional information on web server applications, check these sites
- How the Web Works: Http and CGI explained
- How Stuff Works, How Web Servers Work
Activity
Please complete all activities
- Research available web server applications for Windows, Linux and Mac
- Compile a report
- Create a course portfolio entry
- Publish the entry to your course portfolio web
As an optional, alternate activity
- Install and configure a web server
- place files on the server and access them with a web browser from another computer
Test Yourself
There is no self test for this lesson.