Understanding Web Server Terminology

Definition of Terms, Process, Components and Features

At the most basic level, the process for web communication works as follows: a computer runs a web browser that allows it to request, communicate and display HTML documents (web pages). Web browsers are the software applications that allow users to access and view these web pages and they run on individual computers. The most popular web browsers are Internet Explorer, Mozilla, Firefox, and Safari (for Mac). After typing in the URL (or address) and pressing return, the request is sent to a server machine that runs the web server. The web server is the program that delivers the files that make up web pages. Every web site or computer that creates a web site requires a web server. The most popular web server program is Apache. The server machine then returns the requested web page.

Communication over the Internet can be broken down into two interested parties: clients and servers. The machines providing services are servers. Clients are the machines used to connect to those services. For example, the personal computer requesting web pages according to search parameters (defined by key words) does not provide any services to other computers. This is the client. If the client requests a search from, for example, the search engine Yahoo!, Yahoo! is the server, providing the hardware machinery to service the request. As previously mentioned, each computer requesting information over the Internet requires a web server program like Apache to render the search result intelligible in HTML.

Web servers translate URL path components in local file systems. The URL path is dependent on the server’s root directory. The root directory is the top directory of a file system that usually exists hierarchically as an inverted tree. URL paths are similar to UNIX-like operating systems.

The typical client request reads, for example, “http://www.example.com/path/file.html”. This client web browser translates this request through an HTTP request and by connecting to “www.example.com”, in this case. The web server will then add the requested path to its root directory path. The result is located in the server’s local file system or hierarchy of directories. The server reads the file and responds to the browser’s request. The response contains the requested documents, in this case, web sites and the constituent pages.

{mospagebreak title=Web Servers Features}

Web Servers Features

Although web servers differ in specifics there are certain basic characteristics shared by all web servers. These basic characteristics include HTTP and logging. As previously mentioned HTTP is the standard communications protocol for processing requests between client browsers and web servers. This protocol provides the standardized rules for representing data, authenticating requests, and detecting errors.

The purpose of protocols is to make data transfer and services user-friendly. In computing, the protocols determine the nature of the connection between two communicating endpoints (wired or wireless) and verify the existence of the other endpoints being communicated with. It also negotiates the various characteristics of the connection. It determines how to begin, end, and format a request. It also signals any errors or corruptions in files and alerts the user as to the appropriate steps to take. HTTP is the request/response protocol used specifically for communicating HTML documents which is the language hypertext or web pages are written in. However, responses can also return in the form of raw text, images or other types of documents.

The other basic web server characteristic is logging. This is a feature that allows the program to automatically record events. This record can then be used as an audit trail to diagnose problems. Web servers log detailed information recording client requests and server responses. This information is stored in log files and can be analyzed to better understand user behavior, such as key word preferences, generate statistics, and run a more efficient web site.

There are many other practical features common to a variety of web sites. Configuration files or external user interfaces help determine how much and to what level of sophistication users can interact with the server. This establishes the configurability of the server. Some servers also provide authentication features that require users to register with the server through a username and password before being allowed access to resources or the execution of requests.

Web servers must also be able to manage static and dynamic content. Static content exists as a file in a file system. Dynamic content is content (text, images, form fields) on a web page that changes according to specific contexts or conditions. Dynamic content is produced by some other program or script (a user-friendly programming language that connects existing components to execute a specific task) or API (Application Programming Interface the web server calls upon). It is much slower to load than static content since it often has to be pulled from a remote database. It provides a greater degree of user interactivity and tailor responses to user requests.

To handle dynamic content, web servers must support at least one of the following interfaces:

JSP (Java Server pages);
PHP (a programming language that creates dynamic web pages);
ASP (Active Server Pages, developed by Microsoft);
ASP.NET (also developed by Microsoft, it is the successor of ASP).