World Wide Web (WWW) browser technology is reviewed and analysed as a delivery mechanism for distributed educational multimedia. Using several case studies as examples, existing WWW technology is shown to provide most of the features required to create distributed multimedia applications. The first case study describes a WWW adaptation of an educational tool examining the effectiveness of safer sex in curbing the HIV/AIDS epidemic. The second case study explores WWW tools created for a new tertiary unit on engineering and scientific visualisation. The case study includes a discussion of an animation tool used by students of physiotherapy to visualise human anatomical structure and function. Proposed extensions to existing WWW technology, including the Virtual Reality Modelling Language (VRML) and the Java(TM) programming language are discussed in the context of these case studies.
In 1993, The National Center for Super Computer Applications, (NCSA, Champaign, Illinois, USA), building on earlier work by the European Centre for Particle Physics (CERN, Geneva, Switzerland), released hypertext based client software for interactively accessing graphical and textual data managed by remote information servers. This software, called Mosaic, and similar products like Navigator from Netscape Communications Corporation (Mountain View, California, USA) and HotJava(TM) from Sun Microsystems (Mountain View, California, USA), provides a Graphical User Interface (GUI) to the Internet. When accessed with these interactive tools, the Internet has become known as the World Wide Web (WWW). The use of GUI based web browsers has become widespread, although their suitability for use in educational multimedia has not been widely discussed, and is the subject of this paper.
The user navigates through available information by following static links established by the content provider. The content provider must anticipate all required static navigational paths through the available information when establishing hierarchical links to the data.
Dynamic links created via user input, computer based simulation, and interaction with knowledge based systems are also becoming increasingly common as content providers strive to design systems which promote active learning [Woolf and Hall, 1995]. Dynamic links also provide some advantage when information content cannot be adequately anticipated or collected in advance, or when data cannot be archived due to insufficient space on local storage devices.
Given these features, it is widely held that educational multimedia systems provide specific advantages when used to supplement traditional instructional resources. These advantages include [Edgar and Willis, 1993] :
HTML is transmitted from the information server to the client browser using the Hyper Text Transport Protocol (HTTP), where it is interpreted, formatted, and displayed in a browser window [World Wide Web Consortium, 1995c]. HTTP is also used to transmit user requests for information to the server. Sometimes, noticeable variation may be apparent when comparing the output produced by competing browsers [Berghel, 1992]. In general, however, the technology is designed to be relatively platform independent, making it ideal for cross platform development.
As a minimum, it is assumed that web browsers support the following basic embedded data types, or provide a mechanism to display data in an external helper application running on the client side of a potentially slow transmission link:
Most first generation browsers extend the set of supported media types by displaying unsupported types in a second helper application external to the browser once the file has been transmitted across the link by the server. This mechanism is shown in Figure 1(a). While this approach to extensibility is relatively easy to implement, it tends to present information in a disjointed fashion given that the helper application becomes independent of the browser once invoked.
Figure 1: Extending the set of supported media types through
(a) external helper applications; or (b) plugin extensions.
In contrast, Netscape's second generation browser extends the set of supported media types by using "plugin" browser modules, running on the client side of the transmission link, with data being displayed directly within the browser window. The second generation approach used by Netscape is shown in Figure 1(b). It is important to note that interaction between client and server is stream based, not file based as in first generation approaches, and includes provisions for mouse and keyboard input. Plugin extensions available for Netscape 2.0 include:
In addition to using plugin modules to extend the set of supported media types, interactive graphical applications called applets may be integrated within Netscape 2.0 and HotJava browser windows. Using an architecturally neutral object oriented programming language called Java, content creators author interactive applets for a virtual machine running within the browser, as shown in Figure 2(a) [Goaling and McGilton, 1995; December, 1995]. Because the browsers interpret compiled, operating system and device independent Java code, this technology enables content creators to author a single interactive application for the World Wide Web. The creation of separate operating system specific versions is not required.
Figure 2: Integrating an application program and web browsers using (a) Java Applet interpreted within second generation browser; and (b) using a CGI script on the server side of a first generation browser.
A wide range of Java class libraries are available for graphics and animation and for creating and maintaining applet GUIs.
Java is a multi-threaded language, which may be exploited by multimedia applets to:
Although some WWW sites make effective educational uses of application integration, most sites only use CGI scripts to enter or retrieve information from remote databases, such as phone numbers and addresses. Used for these purposes only, the full educational potential of this technology fails to be realised.
In contrast, a few educators have created innovative educational applications based on World Wide Web technology. In work pioneered at the Lawrence Berkeley Laboratory, students can interactively dissect a virtual frog using a CGI based form [Lawrence Berkeley National Lab, 1995]. In another example, CGI scripts have been used to enable North American school students to collaboratively track the seasonal progress of migratory animals and insects, while also authoring hypertext documents containing additional information on the animals studied [University of Kansas, 1995].
Guidelines for safer sex are a main component of the educational message put forward by public health officials and medical professionals. These guidelines are meant to curtail the transmission of HIV by preventing the exchange of bodily fluids.
The safer sex guidelines have been communicated to the public through the popular media, and have included public service announcements on television and radio, and in newspapers and magazines. Safer sex brochures and posters are distributed at universities, nightclubs, and in public toilets, as well as to international travellers leaving and arriving in Australia through the Commonwealth's "Travel Safe" campaign.
In communities where the incidence of HIV is high, safer sex workshops sponsored by local health departments and community action groups are common. In a forum pioneered by the San Francisco Stop AIDS Project, participants anonymously discuss individual concerns with a trained moderator and a small group of peers in the non-threatening, non- clinical setting of a private home. Participants interact and are encouraged to ask questions, supplementing information found in printed material. At the conclusion of the workshop, participants are asked to make a personal commitment to safer sex.
Because these workshops rely on the interaction of group members, they personalise the safer sex message in a manner that cannot be fully achieved by traditional media sources alone.
Building on the strengths of these approaches to safer sex education, several groups have begun to exploit the World Wide Web to supplement the traditional methods.
Internet bulletin boards and news groups enable individuals to interact, posing and responding to questions on safer sex and HIV/AIDS [University of California San Francisco, 1995a; Internet Roundtable Society 1995]. In essence, these bulletin boards facilitate Stop AIDS Project like meetings in cyberspace, without a moderator and on a global scale. Some individuals may actually prefer a virtual forum as a means of participating in a safer sex educational workshop, as anonymity can be maintained given that the physical presence of participants is not required.
Safer sex material has also been made available for World Wide Web access by various organisations in Australia [Pinkboard, 1995] and the United States [University of California San Francisco, 1995b]. This material includes safer sex guidelines, information demonstrating proper condom usage, updates extracted from current medical journals, and homeopathic HIV/AIDS treatment strategies [HIV EMIR, 1995].
In the study reported here, HTML has been used to link these existing resources with a computer based model of HIV/AIDS epidemiology for use in safer sex education.
Previously, a computer based model was created as a stand alone application using a command line interface to enable students to predict the course of the HIV/AIDS epidemic for a hypothetical community [von Konsky, 1991]. In recent work, this model has been made available to a global audience using CGI scripts to enable the model to be invoked across the Internet from a web page [von Konsky, 1995b].
Parameters related to the sexual activity of the hypothetical community are estimated by the user and entered in a web browser form. These parameters include:
Sample forms with pre-selected parameters consistent with a hypothetical monogamous community, a promiscuous community, a community which ignores the safer sex guidelines, and a community which always tends to practice safer sex are provided. Entering parameters for a community in which members are as responsible as the user is also encouraged.
Anecdotal evidence indicates that while many individuals initially select parameters which stretch credibility, they later tend to enter parameters consistent with their own sexual history or that of their peer group, suggesting that web based HIV/AIDS modelling serves several broad purposes:
The school's computing infrastructure consists of limited numbers of Pentium based Personal Computers, UNIX Workstations, and Apple Macintosh Computers. A means of providing a relatively large number of students access to limited graphics resources was required, while also minimising expenses associated with the purchase of additional hardware or software.
It was recognised that web browsers present a relatively consistent interface, regardless of the hardware or software running on the client and server. It was further recognised that the WWW could provide students with access to graphics resources from home and other remote locations both on and off campus, while at the same time increasing accessibility to the school's existing heterogeneous computing resources.
Additionally, new lecture theatres on campus are designed to facilitate the electronic presentation of course material, enabling video, multimedia output, and web based material to be exploited in the lecture theatre. Where possible, it was felt that all material presented during lectures should be available to students during tutorial sessions, for private study and during revision. Ideally, this should assist students to be better prepared for scheduled sessions since instructional resources can be accessed from home during pre-study.
It was further recognised that graduate engineers must be fully Internet literate to be productive professionals in the twenty-first century. As such, it was decided that use of the Internet, including the WWW, would become an integral part of the school's new engineering course.
As a first step in developing instructional material for the new units, software with educational relevance to the new course was identified. In particular, several software packages, some of them copyrighted freeware, were selected. These include:
In one laboratory session, students enter mathematical formulas for two dimensional curves and three dimensional surfaces in a browser form. When submitted, a corresponding plot is generated at a remote location using gnuplot. The image is then displayed locally in the browser interface window.
During Constructive Solid Geometry (CSG) laboratory sessions, students build complex objects by applying union, intersection, and difference operations to a collection of simple shapes. CSG operations and simple primitives are selected in a browser form. When submitted, a CGI script generates the corresponding POV-Ray description file, enabling attention to be focused on CSG concepts without being diverted by unnecessary POV-Ray syntax.
POV-Ray syntax is presented during another complimentary laboratory session in which an ASCII description of a three dimensional scene is entered by the student in a browser form. The scene description specifies primitives to be rendered, including object size and location; lighting, transparency, and shading characteristics and camera viewpoint. Hypertext links to laboratory exercise material, tutorials, and online documentation is available. When submitted, the scene is rendered using the POV-Ray rendering package running on a high end graphics workstation and invoked by a CGI script at a remote location. The server transmits the resulting image across the network for local display within the browser interface. Iterative changes may be made by following a backward link to the form containing the previous POV-Ray scene description.
As part of this laboratory, students write a POV-Ray description for a scene modelling the water molecule, H2O. The solution should use POV-Ray spheres and cylinders. In a subsequent laboratory session, this exercise is repeated, but using VRML 1.0. Hypertext links to additional information on hydrogen and oxygen are included, and may be invoked when the corresponding VRML atom is selected. All of this is carried out within the structured confines of the laboratory web page, where additional supporting documentation is available if needed.
As a final assignment, students choose a topic in engineering or scientific visualisation and author related web pages. To assist in selecting a suitable topic, several examples are provided.
Examples include an animation tool, originally developed to train students of physiotherapy on subjects in gross, functional, and descriptive anatomy. To visualise terminology used in descriptive anatomy, several pre-rendered animations are available, including examples depicting flexion of the forearm at the elbow, extension, supination, and pronation. Joint angles corresponding to animation key frames are available in a browser form, and may be modified to generate a new and unique MPEG animation sequence. A browser form to produce animation sequences based on muscle activation levels and human biomechanics is also planned [von Konsky, 1994; von Konsky and Zomlefer, 1994].
Other examples include a CGI script which presents the student with hypertext information on the meaning of resistor colour codes. Students can test their knowledge of colour codes by selecting the values of the two significant digit bands, the multiplier band, and the tolerance band in a browser form. This form can then be submitted to POV-Ray which automatically produces a rendered representation of an actual resistor.
Significantly, simulation based web applications like the ones described in these case studies use the information super highway in two directions, not merely as a means of recalling static information laid down in advance by the content provider.
The real challenge for educational web content creators, however, is to create electronic presentations which encourage entrepreneurial learning through dynamic content based in part on computer simulation and knowledge based systems.
In many respects, the WWW is an enabling technology which facilitates bringing existing stand alone simulation tools and related computer applications to a broader global audience.
For command line driven applications like the Safer Sex model and the human arm animation system cited as case studies, this can be done with CGI scripts and minimal effort on the part of the programmer.
When building Java applets, however, additional effort is required, as this effectively means starting from scratch. From the standpoint of the user, the extra effort results in a finished product which is seamlessly integrated with the browser, often using engaging animated graphics and advanced GUI features.
Given that second generation browsers are highly media extensible, the question then arises, which media type should be used for web based educational tools? The answer to this question is somewhat complicated by two seemingly conflicting goals:
MPEG was chosen over VRML 1.0 because although VRML allows the user to move through a three dimensional virtual environment, it does not enable data to be animated. It should be noted, however, that this feature is anticipated in a future version of VRML.
Java, on the other hand, supports extensive class libraries for animation, and will be supported on most platforms including UNIX systems, Windows PCs, and the Macintosh Computers by early 1996. Significantly, geometry data is downloaded and animated on the client side of the transmission link, rather than on the server side as would be the case with an MPEG approach or with other multiple frame media. In many cases, using Java will result in less data being transmitted and an animation sequence of higher quality. A Java implementation of the human forearm animation system is therefore planned for early 1996 when Java becomes stable on all platforms.
It is worth noting that FAST for scientific visualisation in the schools, implemented by NASA's Ames Research Center, is based on a similar premise. This project has demonstrated that remote students and researchers can collaborate more efficiently on many scientific visualisation projects when raw data is exchanged rather than compressed video files, as the latter often requires greater network bandwidth [Watson, 1995].
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|Author: Brian R. von Konsky|
School of Computer Science
Curtin University of Technology
Perth, Western Australia
Please cite as: Konsky, B. R. von (1996). Using the World Wide Web as a delivery mechanism for distributed educational multimedia. In C. McBeath and R. Atkinson (Eds), Proceedings of the Third International Interactive Multimedia Symposium, 203-212. Perth, Western Australia, 21-25 January. Promaco Conventions. http://www.aset.org.au/confs/iims/1996/ek/konsky.html
Available also at: http://kickit.cs.curtin.edu.au/~bvk/iimms96/3rd_IIMMS.html