Open Learning Based on Hyperwave:
A Secure Structured Hypermedia System

Abstract: This paper describes an open learning environment at the University of Auckland which is based on a secure, structured, hypermedia system called Hyperwave. Using common Web browsers, a graphical interface leads students to organised collections of regularly updated information. Read and write access to the material can be controlled using individual and group access rights. In addition, a prototype system has been developed that supports both individual and group annotation of the material. We are also experimenting with a Java applet that provides additional online feedback during both the tutorial and lecture sessions.

1. Introduction

During the past two years, a master's level Multimedia and Hypermedia course has been taught at both the University of Auckland's main city campus and at a satellite campus 12km away. Since there was only one lecturer qualified to teach the course, the decision was made to teach at least part of it electronically. Although sections of the course were taught using "off the-shelf" software such as low bandwidth video conferencing, audio conferencing, white-boards, news groups and e-mail, we have found that the most successful part of the course was the Web site based on Hyperwave - a secure, structured, hypermedia system developed in Graz, Austria. Material has been stored on a server, in HTML, since 1995 and forms the basis of each year's course. Using a common browser, students have a combination of individual and group access rights to various "doors" leading to the electronic Library, Lecture Theatre, Workshop, and Common room. This year we are experimenting with Java applets to both annotate documents and to give online feedback during tutorials and lectures.

2. The Hyperwave Hypermedia System

Hyperwave is a distributed hypermedia system developed at the Institute for Computer Science and Computer Supported New Media (IICM) at the Technical University of Graz, Austria. The principal architects are Prof. Hermann Maurer and Frank Kappe.

Hyperwave (originally called Hyper-G) is based on a more sophisticated concept than most available Web server systems [Andrews et al., 1994b]. The project's aims are [Andrews et al., 1994a]:

• System access using hyperlinks, hierarchical browsing, and searching
• Reducing fragmentation of document collections over multiple systems and servers
• Support for multi-lingual documents
• User identification and access control
• Integration of existing Internet information systems
• Automatic enforcement of document consistency.

Hyperwave offers an integrated working and navigation environment, and relies on the Internet as its base communication medium. A full description of Hyperwave, including all technical details, can be found in [Maurer, 1996a].

2.1 The Hyperwave Server
Hyperwave was developed to store high-volume hypermedia resources, which can be spread over multiple servers. The long-term maintenance and development of databases becomes crucial when databases grow beyond a certain size. To expedite management, particularly of links, Hyperwave imposes a structure on the documents stored in the server. Every document is a member of one or more collections. These collections form a hierarchy.

Besides supporting customary database features such as the assigning of attributes to objects, indexing and searching, the server also maintains a hierarchy of user and group entries. The following attributes can be assigned to a document:

• Read and write permissions for groups and individuals
• Extra search keywords
• Titles in different languages
• Display properties
• Custom attributes
• Direct-debit, from the user's account, of the cost of viewing a document
• Setting of a time period during which the document is visible to the public.

Since attributes are not stored within the objects (as in most Web servers), but in a separate database, they can be efficiently extracted and manipulated. In addition, objects can be locked to ensure they are not updated concurrently.

2.2 Documents
A Hyperwave server can contain various types of documents. The most common types are:

• Text documents in HTML or HTF formats, or as unformatted text. HTF is the native Hyperwave document format.
• Still images in a variety of popular formats (JPEG, GIF, PNG, XPM, TIFF, etc.).
• Movies in MPEG format.
• PostScript documents.
• Three-dimensional scenes in VRML and SDF formats.
• Programs, e.g., Java applets.

It is possible to define links from and to all supported formats, including parts of documents. Thus, Hyperwave can claim to be a true hypermedia system.

Special pseudo-documents can be inserted for scripts that have to be executed on the server upon invocation by a client. Using this mechanism, content can be created on the fly and presented to the client. CGI scripts, as found on the Web, are supported in this category, as well as Hyperwave 's HGI scripts that provide for the session-oriented gateway to external resources (such as access to SQL databases). Other databases can therefore be seamlessly integrated into the hypermedia system.

2.3 Collection Hierarchies
Hyperwave imposes a structure on the documents stored in the server. Every document is a member of one or more "collections". These collections form a hierarchy that is topped by the "Hyper Root", the collection of all servers world-wide.

2.4 Clusters
A "cluster" is a special type of collection that allows tight integration of documents of different types and languages, such as storing different language versions of the same document. The client application requesting the cluster can select a version according to the preferences of the user. A client accessing a cluster might find an English and a German version of a document and decide to display the English version because English has a higher priority for this user. Documents of different types (e.g., a video and an explanatory text) that are stored in a cluster will be displayed in parallel by the client.

2.5 Searching the Collection Hierarchy
The collection hierarchy provides a search space for title, keyword, and full-text searches. Since all sub-collections of the selected collection will be searched, the search scope can be limited to the relevant parts of the database. If these collections are distributed over multiple servers, the servers will be queried in parallel and the result combined.

All text documents inserted into the server are added to a full-text index that allows fast access to the documents. External text extraction programs can be supplied to help the full-text server index the textual content of other documents. Extraction tools for PostScript and PDF documents will be available shortly.

Since Hyperwave is a multi-lingual database, searches can be restricted to certain languages. This applies to both the title and full-text search. Therefore, a separate full-text index is maintained for every language present in the system.

3. Electronic Teaching and Learning Based on Hyperwave

Several open learning environment projects, based on Hyperwave, are already underway at:

• Graz, Austria (see Section 3.1)
• Freiburg, Germany (see Section 3.2)
• Auckland, NZ, (see Section 3.3)

3.1 The Learning And Teaching Environment: Graz University of Technology, Austria
The Learning And Teaching Environment (here called LATE) is a project that integrates a number of current developments in information and communication technology, such as CAI, hypermedia, the World Wide Web, authoring systems, digital libraries, distance teaching systems, and CSCW [Maurer, 1996b]. Maurer has examined why CAI developments in the last three decades never achieved the expected breakthrough in education. He identified the major problems associated with learning and teaching systems in the past, and has designed the project to overcome them.

The project consists of a CAI nucleus built on Hyperwave and HM-Card [Maurer et al., 1995]. Hyperwave's communication facilities allow networked cooperation and collaboration between all users. HM-Card enables teachers to build powerful interactive multimedia presentations and courseware modules. Animation and rather complex question/answer dialogues can be prepared without programming or scripting. Material prepared with HM-Card can be used by itself or fully integrated into the Web environment. It is highly modular and can therefore easily be reused, reducing cost of authoring.

Keeping the authoring effort low is one of the main goals of the project. All modules are stored in Hyperwave servers to build a fully searchable digital library consisting of multimedia Web material, electronic versions of books and journals, etc. By customising pre-existing material, the work of creating electronic lessons is reduced, at least to a certain extent.

Modules can be used in the classroom to replace traditional lecturing aids such as the blackboard or overhead transparencies. Recording of the lecturer's voice and image is supported and it can be added to the lecture material, thus making "authoring on the fly" a reality. Modules can also be used by students for self-study and various features for interaction are provided, so that using a module becomes more than just "page turning in a multimedia enriched book".

Students can browse parts of the digital library related to their lecture material and they can activate simulation modules. They can interact with other students or teachers synchronously using chat and a whiteboard, or asynchronously using bulletin boards or structured discussions. They can test their knowledge by answering questions provided by HM-Card. If parts of a lecture are unclear, questions can be asked which will be answered by tutors or the lecturer, and the question/answer dialogues become part of the lecture and accessible to other users.

3.2 Authoring on the Fly: University of Freiburg, Germany
The Freiburg "Authoring on the Fly" project provides a range of tools for both capturing lectures and playing them back. In addition, lectures have been broadcast via the MBone (Multicast Backbone virtual network [Eriksson, 1994]) to multiple hosts around the world.

The captured material (audio, video, and whiteboard actions) is archived in Hyperwave collections. For playback a specialised Hyperwave viewer, SYNCVIEW, presents the material by synchronising the whiteboard actions with the video and sound.

3.3 A Distributed Learning Environment: The University of Auckland, NZ
At The University of Auckland we have created an interactive distributed learning environment, using new Hyperwave collections supplemented by material from previous years.

Since there is a wide range of hardware that has had to be supported, we have relied on common web browsers that support Java applets. Successful features of the Auckland project include:

1. The course outline, accessible to students from the beginning of the year, consists of lines which both describe the course, and also are links which point to further material automatically after each lecture is held.

2. As the course proceeds, additional lecture material, consisting of PowerPoint slides, are stored in Hyperwave, sequentially linked, and tables of contents generated.
   

   Figure 1: Java Enhanced Screen Showing Feedback Buttons

3. For distant lectures to the university's satellite campus user feedback is of utmost importance. We have included, at the bottom of the browser screen, the simple button-controlled query menus that were described (see Figure 1), as well as text-based question-and-answer dialogue sessions.

4. Students can ask short questions either in written or spoken form.

5. Both students and lecturers can annotate material, and restrict access to the annotations through Hyperwave's group access rights.

6. The system can be used in either asynchronous or synchronous modes.

4. Conclusion

We have to agree with Rossman [Rossman, 1992] that in many senses we are like Arthur C. Clarke's "fish trying to imagine fire". Even specialists are having difficulty keeping up to date when relating their own fields to the Internet. However, as Rossman [Rossman, 1992] predicted, we are seeing the development of specialist hubs that students and teachers, worldwide, can hook into. And as Bates [Bates, 1993] states, "Teachers then will increasingly be advisers and managers and facilitators of learning, rather than providers of information." Systems such as HyperWave may play a part in providing the information in a useable, manageable form.

References

[Andrews et al., 1994a] Andrews, K., Kappe, F., and Maurer, H. (1994a). Hyper--G and Harmony: Towards the next generation of networked information technology. Technical report, IICM.

[Andrews et al., 1994b] Andrews, K., Kappe, F., and Maurer, H. (1994b). The Hyper-G network information system. In Special issue: proceedings of the Workshop on Distributed Multimedia Systems, Graz, Austria.

[Bates, 1993] Bates, A. W. (1993). Educational aspects of the telecommunications revolution. In Proc. IFIP TC3 Third Teleteaching Conference Teleteaching 93, pages 1--10.

[Eriksson, 1994] Eriksson, H. (1994). MBONE: The multicast backbone. Communications of the ACM, 37(8):54--60.1(3).

[Maurer, 1996a] Maurer, H., editor (1996a). HyperWave: The Next Generation Web Solution. Addison-Wesley, UK.

[Maurer, 1996b] Maurer, H. (1996b). LATE: A unified concept for a learning and teaching environment. J.UCS (Journal for Universal Computer Science), 2(8):580--595.

[Maurer et al., 1995] Maurer, H., Scherbakov, N., and Schneider, A. (1995). HM-Card: A new hypermedia authoring system. Journal for Multimedia Tools and Applications, 1(3).

[Rossman, 1992] Rossman, P. (1992). The Emerging Worldwide Electronic University: Information Age Global Higher Education. Greenwood Press, Westport, CT.