What is a Web Server?


Introduction

TCP/IP, Internet, World Wide Web, Browsers, HTTP, HTML. Where does Web Server/400 fit with all these new terms flooding the corporate and private world? First take a look at the general meanings of these terms.

TCP/IP
A protocol used to carry data over a local or wide area network.

Internet
The name given to the now immensely popular, world-wide collection of networks-most of which are running TCP/IP.

World Wide Web
The term used to describe a collection of cooperating protocols that ride on top of the Internet and make it more accessible and powerful.

Browsers
The very visible end-user tool used to view the material that is available on the World Wide Web.

HTTP
The protocol (Hypertext Transfer Protocol) that allows Web browsers and Web servers to communicate over the World Wide Web.

HTML
The standard markup language (Hypertext Markup Language) that allows Web browsers to display the rich and user-friendly information stored on the World Wide Web.

A Web Server's Role

A Web server is the caretaker of all the information that travels over the World Wide Web (WWW) to the Web browsers. A person interested in surfing the WWW would start up a browser and specify a place to start looking. Most all the information received while surfing comes from a Web server.

A Web server is responsible for managing and delivering the content that an organization wishes to make available over the WWW. The Web server takes a large repository of information and makes it easily available to whomever wants to view it. This information can be in an almost endless number of different shapes, forms, and sizes. The most popular of which include HTML, text, images, audios, and movies.

Who Deals with a Web Server?

Who sees the Web server? Most users of the WWW never really see a Web server. Their view of the Web is the browser tool they are using and the information they obtain. The server end of the WWW is mostly seen by the person(s) that administers the Web server and the people that are responsible for providing the content for a Web site.

Administrators

Every Web site will have one or more administrators of the Web server. Whether this is an official position or an informal one, at least one person will perform administrative tasks on the server. A popular title for people in this position is Webmaster.

The administrator is responsible for installing the Web server, doing initial configuration, performing on-going configuration, monitoring the accesses to the server, monitoring errors, organizing at a high level where the content is stored, answering questions from end-users, and ensuring that the security and integrity of the machine is not compromised. These tasks are in addition to normal service tasks like backing up data, ensuring the machine is operating correctly, and ensuring that it is accessible.

Content Creators

Making sure the Web server is running correctly and that it can be accessed by end-users, doesn't mean much if the server doesn't have anything to serve. The content creators are responsible for providing the information that the Web server will provide.

Generally, this task is handled by many different people. Content creators may be from the company's marketing department, graphic arts department, technical staff, project management, or individual employees. Many times, talents from all of these areas need to be combined in order to create the best content.

Content creators are responsible for deciding what goes on the Web server, creating the artwork, creating the HTML documents, organizing the information, making the content homogenous, keeping the content up-to-date, integrating existing or outside data with the Web server, and writing programs (scripts) that interact with browsers.

Notice that the descriptions of the administrators and content creators are quite different. It may not be easy to find one individual (or a set of individuals) that is well suited for both tasks.

Hypertext Transfer Protocol Basics

You don't need to understand anything about the Hypertext Transfer Protocol (HTTP) in order to administer a server or create content for it. But knowing a little can be helpful to the administrator and essential for the more advanced content creator.

On the WWW, a browser always initiates a conversation with a Web server. This happens every time someone clicks on a hyperlink in an HTML document or opens a new Uniform Resource Locator (URL). From the URL, the browser can determine which Web server to talk to. This is where the conversation begins. The browser asks that server for the document the user requested and also supplies some additional attributes about the request. This is the request. The most important part of the request is the document that is being requested. This takes the form of a URL-path.

The Web server accepts the conversation from the browser. Part of this, is receiving the URL-path. The server then decides what is being requested and how to handle the request. If everything is okay, the server sends back to the browser some attributes about what is being served, and then the server sends back the content of the document. Both sides then end the conversation.

It is important to note that there is no login process with HTTP nor is there an on-going conversation between browser and server. Unlike other Internet protocols such as FTP and Telnet, a user does not, in normal operation, provide a userid and password, or start a user-specific job on the server machine. Also, each browser request is treated as a single entity. So, if a browser needed to get several documents from the same server, the browser would initiate a separate request for each document.