Most current hypertext systems use proprietary data formats for storage. Some researchers have tried using Relational Data Base Management Systems (RDBMS) to implement hypertext applications [Schutt & Streitz, 1990], [Meyrowitz, 1986]. There exists a large class of applications for which relational database management systems and other more conventionally structured database systems are too limited. These applications can be characterized as complex, large-scale, data-intensive programs such as CAD/CAM systems, documentation management systems, hypermedia systems, and geographical information systems. This class of applications needs a database model that is more expressive and flexible than the relational model. Some researchers believe that object-oriented databases can meet the data handling requirements of such applications.
Among the many research issues in the area of hypermedia, database requirements of hypermedia systems have received very little attention. HyperBase, based on an object-oriented data model, was implemented on Sybase, a RDBMS. Similarly, Intermedia was originally implemented on INGRES and later on C-Tree. Very little work has been done in the usage of Object-Oriented Data Base Management Systems (OODBMS) for hypermedia applications. The use of an OODBMS for a hypermedia system is an excellent marriage between the rigorous infrastructure and modeling abilities of object-orientation and the flexibility and navigational access to information characterized by hypermedia [Lange, 1993].
Frank Halasz had originally identified seven issues for next generation hypermedia systems [Halasz, 1988]. Other researchers have come up with a few more over the past few years [Lange, 1993], [Fountain et al., 1990]. Object-oriented database management systems seem to meet most of these requirements.
Object-oriented technology provides the ability to model, to develop and to manage complex systems that cannot be easily implemented with current technology. Hypermedia systems constitute an emerging class of complex management information systems. They should facilitate distributed memory, distributed processing, and distributed knowledge on a network. An object oriented approach to hypermedia may help us achieve this goal much better than current approaches. However, research in this area is still in its infancy and there are many open issues to be investigated. Any breakthroughs in this arena will take us closer to realizing Ted Nelson's goal, "Everything should be available to everyone. Any user should be able to follow origins and links of material across boundaries of documents, servers, networks, and individual implementations. There should be a unified environment available to everyone providing access to this whole docuverse." [Nelson, 1991].