The social shaping of technology

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functionality is implemented in Java and works on the client side, and another part works on the

server side. The parts communicate over the Internet. While the pure Java solution looks simpler

(just a new language to build an AIES), the client-server architecture offers a more attractive

choice for developing Web-based tutors. It is a definite choice for porting a standalone

interactive tutor on the Web. D3-WWW-Trainer [20] and AlgeBrain [1] demonstrate how to reuse

the intelligent functionality of an earlier standalone tutor by changing it to a server-side

application and developing a relatively thin "brainless" Java client that implements interface

functions and communicates with an intelligent server. Event relatively small newly implemented

interactive tutors such as ADIS [50] and ILESA [30], which could be easily implemented in pure

Java, can benefit from client-server architecture for such reasons as central student modeling.

Finally, an overhead of the client-server approach (the need to have a distributed system) is not

very big since Java naturally supports several ways of client-server communications -

HTTP/CGI, sockets, or RMI/CORBA. We think, that the client-server architecture will become

very popular in the coming years as a standard way of implementing Web-based interactive

tutors and a way to implement all kinds of highly interactive Web-based AIES. We already see

examples of using it for implementing pen-based interface in WITS-II [27] and an animated

pedagogic agent Vincent in TEMAI [38].

2.2 Adaptive hypermedia technologies in Web-based education

Adaptive hypermedia is a relatively new research area [7]. Adaptive hypermedia systems

apply different forms of user models to adapt the content and the links of hypermedia pages to

the user. We distinguish two major technologies in adaptive hypermedia: adaptive presentation

and adaptive navigation support. Education always was one of the main application areas for

adaptive hypermedia. A number of standalone (i.e., non-Web-based) adaptive educational

hypermedia systems was built between 1990 and 1996. First Web-based AIES that use adaptive

hypermedia technologies were reported in 1996 [12; 17]. Since that the Web has become the

primary platform for developing educational adaptive hypermedia systems.

The goal of the

hyperspace orientation and navigation by changing the appearance of visible links. Adaptive

navigation support (ANS) can be considered as a generalization of curriculum sequencing

technology in a hypermedia context. It shares the same goal - to help students to find an "optimal

path" through the learning material. At the same time, adaptive navigation support has more

options than traditional sequencing: it can guide the students both directly and indirectly. In a

WWW context where hypermedia is a basic organizational paradigm, adaptive navigation

support can be used very naturally and efficiently. There are several known ways to adapt the

links [7]. Two examples of ANS-based standalone systems are ISIS-Tutor [10] with adaptive

hiding and adaptive annotation and Hypadapter [24] with adaptive hiding and adaptive sorting.

The three ways that are most popular in Web-based AIES are direct guidance, adaptive link

annotation, and adaptive link hiding.

Direct guidance implies that the system informs the student which of the links on the current

page will drive him or her to the "best" page in the hyperspace (which page is "best" is decided

on the basis of student's current knowledge and learning goal). Often, if a link to the next best

page is not presented on the current page, the system can generate a dynamic "next" link. As we

can see, adaptive navigation support with direct guidance is almost equivalent to curriculum

sequencing technology. There are some differences though (in addition to the different origin). A

page suggested by a direct guidance technology is always a page of the existing hyperspace. The

student usually could reach this page in one or several steps without the system guidance. The

guidance just helps the student to realize that this page is "best" and to get there fast. In an ITS

with adaptive sequencing a "page" with next best task or presentation could be completely

generated from system's knowledge, thus the student has no ways to get to this material others

than using sequencing. Also, direct guidance usually applies a one level sequencing mechanism

(in comparison with two-level sequencing in most ITS): the best page is simply selected from the

adaptive navigation support technology is to support the student in