Simply put, information in hypermedia databases has three typical features. Firstly, the information is not homogenous. Different forms of information objects such as text, audio and pictures may be used alone or together, and information which is semantically different is tied together. Secondly, hypermedia systems have a high degree of user interaction.
Thirdly hypermedia information is structured. If the hyperbase
is to be built from information already possessing structure,
this structure may be retained, if so desired. Hypermedia may
thus be employed to model existing structure. For example, a hyperdocument
based on a book may be structured in the same way as the original.
Conversely, hypermedia may also be used to introduce new structure
in the information. An author writing about a hypermedia topic
may use whatever structure s/he desires. Hypermedia may thus also
be used to structure information.
Now let us examine some typical applications for hypermedia. To
place this in context, we shall start by describing a system which
probably would not lend itself to hypermedia.
An example of a system less suited for hypermedia. An
imaginary vehicle register consists of a number of items, with
each item (object) representing a vehicle. Each object is structured
identically, with a fixed number of fields describing the object's
attributes. The content of the information database thus has a
high degree of homogeneity. There is little relation between the
individual objects, as a vehicle does not have a direct link to
another vehicle. Inquiries may be made using vehicle registration
numbers or owner names. Directing inquiries to particular vehicles
is rarely necessary, the typical transaction is periodically processing
the entire database. One such process may be periodical printing
of summons for technical checks.
Such a system will not be able to utilise the special features
offered by hypermedia. As mentioned above, hypermedia information
databases are homogenous, and the ability of hypermedia to connect
different information objects is not very interesting in this
case. Each object is independent on other objects, and there is
no way the vehicle register can utilise hypermedia's ability to
structure information. Moreover, a vehicle register would have
little need for user interaction.
The next items show some application areas well-suited for hypermedia.
This is an informal list, more formal definitions are given in
Conclin (Conclin 87, p. 20).
Literature systems. Different types of literature require
organising the material, as well as references to other literature.
Literature systems lend themselves well to the rich ways of structuring
information afforded by hypermedia. Documents are kept together
by means of organisation links. This structure may be created
by the author, or it may be the original structure of a document
which has been converted from printed text to hypermedia.
References to other parts of the document and to other documents
are handled by reference links. This allows direct references
to other documents, if the other document are in the hyperbase.
A document featuring a literary analysis of Ibsen's "The
Wild Duck" may refer directly to scenes in the play if the
play is in the hyperbase. Those parts of the play referenced by
the analysis document may thus appear to be integral parts of
it though in reality the play is an independent document in the
hyperbase. Users often may make their own private notes by means
of private reference links.
Publishing. Compared to traditional printed information
media, hypermedia has the advantage of being able to present other
information than text and pictures. Information objects such as
audio and film may be included in a document. As this publishing
is electronic, it will be easier to distribute than traditional
printed matter.
One concrete instance of a system used for publishing is The
Perseus Project (Crane 91). This information base with hyperfunctionality
contains information on ancient Greece. An advantage with hypermedia
in this connection is that the price is substantially lower than
that for printed material. Crane especially mentions the price
of printing photographs, which is expensive to print but inexpensive
in electronic media.
Instruction systems. Hypermedia is often employed in interactive
instruction systems. The student may move around at will in the
information, hopefully learning while jumping from node to node.
NoteCard's IDE extension (Jordan, Russel, Jensen, Rogers 89) is
especially adapted for developing instruction systems. Such systems
often place heavy demands on the hypersystem, as merely browsing
the system alone is insufficient. Instruction systems require
the ability to guide the student through the material, creating
recommended paths to follow. A simple way to add comments is also
required.
Problem-solving systems. This type of system is used for
intergroup communication. When using hypermedia's opportunities
for allowing a number of users to access the same information
set, a work group may seek solutions to different issues. Discussions,
document sharing, and the ability to let work-group members comment
on the work of other members are typical features of such systems.
An example of a concrete application may be the process of system
development. One system especially intended for this use is gIBIS
(Conclin, Begeman 88).
Idea tools. A number of experts have argued that the linear
structure of traditional documents is inadequate for representing
thinking and ideas. As hypermedia offers a non-linear structure,
it may well be an appropriate tool for structuring thoughts and
ideas. The NoteCards system is intended as a personal idea tool.