Information Technology Reference
In-Depth Information
7.8 Virtualisation
Virtualisation is a term used in many areas. The common theme of all virtualisation
technologies is the hiding of technical detail, through encapsulation. Virtualisation
creates external interfaces that hide an underlying implementation. The benefits for
preservation arise from the hiding of the specific, changing, technologies from the
higher level applications which use them.
The Warwick Workshop [
69
] noted that Virtualisation is an underlying theme,
with a layering model illustrated in Fig.
7.15
.
Fig. 7.15
Virtualisation layering model
7.8.1 Advantages of Virtualisation
Virtualisation is not a magic bullet. It cannot be expected to be applied everywhere,
and even where it can be applied the interfaces can themselves become obsolete and
will eventually have to be re-engineered/re-virtualised, nevertheless we believe that
it is a valuable concept. This is a point which will be examined in more detail in
Chap. 8
; the aim is to identify aspects of the digital object which, we guess, will
probably be used in future systems.
This is because, for example, in re-using a digital object in the future the appli-
cation software will be different from current software; we cannot claim to know
what that software will be. How can we try to make it easier for those in the future
to re-use current data?
The answer proposed here is that if we treat a digital object, for example, as an
image then it is at least likely that future users will find it useful to treat that object as
an image - of course they may not but then we cannot help them so readily. If they do
want to treat the object as an image then we can help them by providing a description
of the digital object which tells them how to extract the required information from
the bits.
For a 2-dimensional image one needs the image size (rows, columns) and the
pixel values. Therefore if we can tell future users:
