The very first person to directly formulate the hypermedia concept
was Vannevar Bush. President Roosevelt appointed him manager of
the organisation which co-ordinated technological research in
the USA during World War II. In 1945 he published the article
"As we may think" in the magazine The Atlantic Monthly,
addressing some of the problems faced by modern science. Even
at that time the number of scientific publications was high, and
Bush emphasised two resultant problems: finding the time to keep
up-to-date professionally, and remembering all this information.
He also pointed out the dynamic aspects of scientific publications,
claiming (Bush p. 45):
"A record, if it is to be useful to science,
must be continuously extended, it must be stored, and above all
it must be consulted."
In proposing a solution he launched the idea of an imaginary machine
to handle these problems, The Memex (Bush 45). The Memex
was intended to structure information by association, in contrast
to traditional structuring by index. Using links ("trails"),
information units would be chained, and these were to be followed
through a series of associations by pressing a button. The Memex
was never realised, but many people consider this the precursor
to hypermedia.
The concept of hypertext, and later hypermedia was created by
Theodor Holm Nelson, the man behind the hypermedia system Xanadu.
Fascinated by the ideas of Bush, from the 1960s onwards Nelson
developed them further, placing the following content in the concept
of hypermedia (Nelson 90, p. 0/2):
"Well, by 'hypertext' I mean non-sequential
writing -- text that branches and allows choices to the reader,
best read at an interactive screen."
As we see, Nelson assumes that both the reading and the writing
process would be supported by hypertext. Nelson placed special
emphasis on the non-sequential nature of hypertext. Information
must follow its natural structure, not being constrained by the
linear structure to which traditional writing must adhere, for
example a textbook which has to be read from cover to cover. Generally
this is also what Bush meant by following information via links
("trails"), while Nelson introduced the term links
for these paths through information.
It is well worth noting that Nelson does not assume the use of
information technology to represent hypermedia. Hypermedia is
rather a method for structuring information. New information is
accessed by "jumping" from a reference point directly
to the referenced information. Nelson cites a newspaper front
page as an instance of "manual hypertext" (Nelson 90,
p. 1/17), the headlines with their page references being the reference
points for the information found in the paper.
In parallel with Nelson, Douglas Engelbart researched some of
the same ideas at the Stanford Research Institute (Engelbart 63)
and (Engelbart 78). This yielded the development of NLS (oNLine
System), later Augment. In contrast to Bush and Nelson,
Engelbart assumed an overarching hierarchical structure of information
in hypertexts, enabling links across these structures. In general,
nonetheless, Engelbart's theories agree with those of Nelson and
Bush.
Engelbart focused especially on the opportunities provided by
hypertext for group work, and much of his research was on using
hypertext as a tool for work groups. Several persons might share
the same document, working on it at the same time. It would also
be possible to work on the same document on the same screen at
the same time, so that two persons would sit in different locations
while seeing the same screen, which they could both edit. WYSIWIS
-"What You See Is What I See". Furthermore, electronic
mail was used to transfer documents and structures. All of these
features have now been implemented in Augment (Engelbart 78).
Another major figure in hypermedia research, Jeff Conclin, offers
a more pragmatic description of hypertext (Conclin 87, p. 17):
"The concept of hypertext is quite simple:
Windows on the screen are associated with objects in a database,
and links are provided between these objects, both graphically
(as labelled tokens) and in the database (as pointers)."
This is a direct description of how a typical hypertext system
organises information. Conclin assumes the use of a computer with
a graphical interface. The information is stored in a database,
suggesting that some typical database routines, such as taking
back-up copies, data integrity and real-time transactions are
handled for the user by the system.
Hypertext was originally constructed for purely text-based systems,
but as computer features evolved, making it possible to represent
other information as well, for example computer graphics, the
term hypermedia was introduced. This concept was also created
by Theodor Holm Nelson. As today's work stations are able to represent
different types of multimedia, this difference has become less
important. The rest of this text will thus employ the term hypermedia.
Based on the work of Bush, Nelson, Engelbart and Conclin we may
list typical characteristics of hypermedia. These qualities largely
agree with those of existing hypermedia systems:
The literature on this occasionally appears to use the terms hypertext
and hypermedia in a wider sense, so that the requirements above
are not met. We will use "hypermedia" in the stricter
sense of the term in the rest of this lesson. Hypermedia is primarily
a means for information exchange among persons.
At present work is underway to develop a common reference work
for hypermedia, "The Dexter Hypertext Reference Model"
(Halasz, Schwartz 94), which aims to standardise hypertext terms
and concepts. A common standard may clarify terminology, permitting
various hypersystems to be considered more homogeneously. Furthermore,
such a standardisation may form the basis for exchanging hyperdocuments
among different hypersystems. However, it is so far uncertain
whether this standard would be appropriate for describing existing
systems, as it may set too strict requirements, thus excluding
some existing systems (Halasz, Schwartz 94, p. 38). Because of
the lack of standards, formal descriptions and methods, hypermedia
must be regarded as a still immature science. This would include
both hypermedia itself as a technique and its applications. An
important area for research is developing methods or models for
hypermedia construction, and there is much work still to be done
here. Initial work in this area suggests dividing these models
into:
From the first category three models are especially familiar:
The Hypermedia Design Model - HDM, The Hypermedia Data Model -
HM-data model, and The Relationship Management Design Model -
RMD. Examining these more closely would be beyond the scope of
this course. The Department of Information Technology at NTNU
is continuing its work on the further development of models for
hypermedia systems. One post-graduate study is aiming to develop
an object-oriented framework for hypermedia systems. Another is
attempting to exploit rapid computer systems to navigate in normal
data files as if they had been stored as hyperstructures. Data
structure would then be generated on the fly based on a descriptive
model.