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An Introduction to the World-Wide Web

Brian Kelly


This paper gives an introduction to the World-Wide Web. It describes the client/server architecture of WWW and gives some examples of its use within the academic community.

The World-Wide Web

The World-Wide Web (often referred to as WWW or W3) is a distributed multimedia hypertext system:
Information on WWW may be located on computer systems from around the world.
The information can include sound, graphics and video, as well as text.
The information can be accessed by using simple hypertext techniques, such as clicking or a highlighted phrase.

Client/Server Architecture

WWW is based on the client/server architecture, illustrated in Figure 1.

Figure 1 WWW Client/Server Architecture.

The client program (often called a browser) runs on the local workstation. When a hypertext link is activated, a request is sent to the server software, which normally runs on a remote server system. The server software (e.g. CERN httpd) will then transfer the file to the client.


A variety of server software packages are available, including the widely CERN and NCSA httpd servers for Unix, commercial servers (which may be more reliable or provide additional features such as security) and servers for Apple Macintosh and the PC.

When setting up an institutional WWW service, the following server issues need to be addressed:


A variety of browser clients are available, including When choosing a browser the following issues should be considered:

Extending WWW

Running Software On The Server

WWW can not only be used to deliver multimedia documents. The Common Gateway Interface (CGI) is a mechanism by which software running on the remote server can generate a virtual document. The use of CGI programs was used initially for developing searching tools. However it is now being used for developing distributed teaching and learning applications.

Running Software On The Client

A WWW server delivers a MIME document to the browser. The browser will be configured to process MIME documents. For example HTML documents will be displayed by the browser, whereas the JPEG MIME type will normally be passed to an external graphical viewer. A Chemical MIME type has been developed by Henry Rzepa (Imperial College) and others. When such a MIME type is delivered, the browser can be configured to pass the document to a molecular modelling program.

Figure 2 WWW MIME Types.

This mechanism enables documents to be transferred from a remote server and passed on to an application on the local machine. New mechanisms are under development which will enable applications on the client to communicate with WWW browsers. The new mechanisms include CCI (Common Client Interface) and W3A (WWW Applets).


WWW is many things to many people. It can be regarded as a system for the academic world, for the commercial world and for the cultural and social world. It be regarded as a distributed file viewer or as a distributed program manager. It is also, ambiguously, referred to as the "Internet killer application". A number of examples of the use of WWW in the academic world are given below.

Research Use

Many research papers, results, proposals, etc. are being made available on WWW [1]. One potential benefit of this is in making state of the art research material available to undergraduate students.

Experimental Research at CERN.


Libraries are beginning to make material available on w. w. W. This may provide a consistent interface between a library catalogue and other services on WWW


This illustrates access to a backup copy of the Library catalogue at the University of Leeds [2]. The backup copy, held in a BRS free text retrieval system, is accessed on WWW by using a CGI gateway.


Campus Wide Information Systems (CWISes) are being developed on WWW. This illustrates the CWIS at the University of Bradford [3].

Bradford CWIS.

Distributed Teaching and Learning

WWW is being used to develop distributed teaching and learning systems. The Frog Dissection Kit is one of the best known examples of a distributed teaching application.

Frog Dissection Kit.

Students are being given the opportunity to develop their own authoring skills. As illustrated below, Fine Arts students at the University of Leeds write multimedia essays. The essays will be used as an information resource by subsequent student groups.

Student Authoring Skills.


WWW is being used as a scientific visualisation tool. It may be difficult to visualise a molecule from simple reading text and viewing a 2D image.

As illustrated below, the data used to produce the 2D image may by retrieved and loaded into a local molecular modelling package, enabling the molecule to be manipulated [6]. The technique can also be used for teaching and learning purposes.

Control Systems

WWW is being used to provide integration with control systems. Mark Cox, University of Bradford has developed a robotic telescope which can be controlled using a WWW browser [7].

Control Systems.


Many conference organisers are making their conference proceedings available on WWW. The conference papers for the Mosaic and the Web conference held in Chicago in October 1994 were available on WWW at the start of the conference [8]

Collaborative Systems

Collaborative systems are being developed on WWW. WIT (WWW Interactive Talk) is one example of a collaborative system which resembles Usenet, but provides a mechanism for voting on a topic.

Collaborative Systems.

WWW And Open Systems

It is likely that not only will we see increasing uptake of existing types of services on WWW, but also the development of new types of services. The development of WWW is helped by the open nature of WWW:


[1] Information about CERN research activities is available at the URL

[2] The University of Leeds library catalogue is available at the URL

[3] The University of Bradford CWIS is available at the URL

[4] The Frog Dissection Kit is available at the URL

[5] The Fine Art service is available at the URL

[6] Information about the Chemical MIME type is available at the URL

[7] The Robotic Telescope is available at the URL

[8] The Mosaic and the Web conference proceeding are available at the URL

[9] WIT is available at the URL

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