Information Technology Reference
In-Depth Information
9.5 Software as the Digital Object Being Preserved
When software itself is the digital object being preserved all the above applies.
However there are some additional considerations because to do some of what
is described in the previous sections could be very complex. This is because the
software which “uses” a software digital object is an operating system or virtual
machine.
The options discussed above become:
A. If (s)he does not have the correct version of operating at hand then (s)he at least
has the option of trying to obtain it from a Registry/Repository of Representation
Information - because (s)he knows what is needed.
a. An important variant of this is the use of operating systems running in
emulators, described in
Sect. 7.9
.
B. If the application cannot be run then it might be possible to take the source code,
if available, and port it to an available operating system or convert it to another
programming language.
The remaining option, of using a data description language, is not an easy one. An
example of this could be a Java application, where we could argue that Java byte
code is well described; this would require a re-implement a Java Virtual machine -
quite a daunting task.
The testbed example in Sect. 19 provides further examples of using the
Representation Information Network for software.
9.6 Digital Archaeology, Digital Forensics and Re-Use
The above starts from the assumption that Representation Information is avail-
able, as should be the case where digitally encoded information is being adequately
preserved.
There are times when one is not in such a fortunate position, for example where
one finds some digital data but does not know much about it. In such a case one may
be able to find the format (i.e. the appropriate Structure Representation Information),
as discussed in
Sect. 7.4
. What will be much more difficult to do is to find the
semantics associated with it. For example one may be able to discover that a file is a
PDF. This allows one to render the contents of the file. This does not mean that one
understands or can use the information it contains - for example the rendered text
might contain a string of “1”s and “0”s, as described at the start of this chapter, or it
might be in some unknown language.
In some cases this has not been an insuperable problem - an analogy may be
drawn with the interpretation of cuneiform - but this can take a considerable amount
of time and effort. Therefore this is a method of last resort.
