Information Technology Reference
In-Depth Information
7. Describe Simple Object
COMPONENT
: Simple Object
Virtualiser (see
Sect. 17.3
)
The “simple” in this case refers to the type of
Information Object; this is a non-trivial component
involving descriptions of the Structure as well as
the Semantics of relatively self-contained Objects
8. Describe Complex Object
COMPONENT
: Complex Object
Virtualiser (see
Sect. 17.3
)
A Complex Object is one that can be described in
terms of several, possibly a large number of, both
Simple Objects and Complex Objects and their
inter-relations. In particular, the Complex Object
Virtualiser has to cope with multiple partial copies
of the datasets forming the referred Object and with
the management of the lower-level objects in a
fully distributed environment.
9. Some of the Objects are created
“on-demand”. It may be true to say
that most Information is created in
this way.
COMPONENT
: On-Demand Object
Virtualiser (see
Sect. 17.3
)
An On-Demand Object is one (Simple or Complex)
that can be referred to by the available knowledge
and can be instantiated on request.
10. Produce OAIS Preservation
Description Information (PDI)
COMPONENT
: Preservation
Description Information Toolbox (see
Sects. 17.7
,
17.8
,
17.11
,and
17.9
)
PDI includes Fixity, Provenance, Reference and
Context information. The PDI Toolbox has a
number of sub-components that address each of
these and guide the user to produce the most
complete PDI possible. Knowledge capture
techniques should also be applicable here.
Having created the Virtualisation information (which includes and extends the OAIS concept
of Representation Information), it must be stored in an accessible location.
11. Store DRM/Virtualisation
Information/Representation
Information in Registry
COMPONENT
: Registry
We take the general case that it is stored in an
external registry in order to allow the possibility of
enhancing the Representation Information etc. to
cope with changes in the technologies, Designated
Communities etc.
The alternative of storing this “metadata” with the
data object is possible but would not address
long-term preservation because:
•
the RepInfo cannot be complete;
•
the RepInfo cannot easily be updated;
•
the RepInfo has to be repeated for each object or
copy of the object and consistency cannot easily
be maintained;
•
the effort of updating the RepInfo cannot easily
be shared, in particular when the originator is no
longer available.
In addition to Representation Information, there may also be keys, public and private, for
encryption etc. that need to be available over the long term.
