Tonge, Rzepa, Yoshida, page 2

which can request services from a remote server. Much of the impetus for this change is coming from the increasing use of the Internet for electronic commerce and other processes requiring secure transactions and authentication, a feature not provided by the original Web model. Security in this sense requires some form of data protection, which would prevent a third party from gaining unauthorised access to the information. Authentication implies a mechanism for tracing the origin of the original creator of the information or computing resource in a highly trusted manner. Increasingly, one is also seeing the original "few-servers to many-client" Web model evolving into one where almost any computer can also be easily configured to become an information or computing server. This in turn has brought a potential for uncontrolled global document and resource publishing, and with it has a realisation that authentication of the server-side of this model is becoming essential. Such authentication in turn would eventually result in a more trusted electronic publishing and computing model in which a mechanism for establishing the authenticity of published materials can be incorporated.

By 1998, only two major browsers, Netscape Navigator and Microsoft Internet Explorer, were widely deployed on client machines. Each browser had the facility to execute so-called Java applets downloaded from the server. This network computing architecture (NCA) model is often referred to in terms of a thin-client connected to an application server. Browser technology had become perceived as having developed to the point where it has become the universal platform-independent front end for Extranets and corporate Intranets, providing an (almost) standardised interactive interface to remote service requests. In effect, there was a strong push for the NCA to become a new standard for distributed client-server operations. The key technology for implementing this was seen as Java, which is an object-oriented programming language developed from C++ and first released by Sun Microsystems in 1995. Relatively easy to learn and with a range of application libraries, it has rapidly taken off as a platform-agnostic programming language for the Web. Applications written in the Java language compile to neutral bytecode classes, rather than binary machine code, and hence are considered as portable, or platform-neutral. These class files can be downloaded from a central server and then run on any system, so long as that system supports a Java Virtual Machine (JVM), an executable which can interpret the bytecode. Browsers such as Netscape Navigator and Microsoft Internet Explorer include a Java Virtual Machine and a Java applet will therefore run on all machines for which the browser has been implemented. The ability of Web technology to deliver re-usable software components, such as applets, means it has become an ideal vehicle for developing Distributed Computing environments (Table 1).