David Giaretta

Advanced Digital Preservation

There is growing recognition of the need to address the fragility of digital information, on which our society heavily depends for smooth operation in all aspects of daily life. This has been discussed in many books and articles on digital preservation, so why is there a need for yet one more? Because, for the most part, those other publications focus on documents, images and webpages objects that are normally rendered to be simply displayed by software to a human viewer. Yet there are clearly many more types of digital objects that may need to be preserved, such as databases, scientific data and software itself.David Giaretta, Director of the Alliance for Permanent Access, and his contributors explain why the tools and techniques used for preserving rendered objects are inadequate for all these other types of digital objects, and they provide the concepts, techniques and tools that are needed. The book is structured in three parts. The first part is on theory, i.e., the concepts and techniques that are essential for preserving digitally encoded information. The second part then shows practice, i.e., the use and validation of these tools and techniques. Finally, the third part concludes by addressing how to judge whether money is being well spent, in terms of effectiveness and cost sharing.Various examples of digital objects from many sources are used to explain the tools and techniques presented. The presentation style mainly aims at practitioners in libraries, archives and industry who are either directly responsible for preservation or who need to prepare for audits of their archives. Researchers in digital preservation and developers of preservation tools and techniques will also find valuable practical information here. Researchers creating digitally encoded information of all kinds will also need to be aware of these topics so that they can help to ensure that their data is usable and can be valued by others now and in the future.To further assist the reader, the book is supported by many hours of videos and presentations from the CASPAR project and by a set of open source software.

Preservation of Intelligibility of Digital Objects

We live in a digital world. Everyone nowadays works and communicates using computers. We communicate digitally using e-mails and voice platforms, watch photographs in digital form, use computers for complex computations and experiments. Moreover information that previously existed in analogue form (i.e. in paper) is now digitized. The amount of digital objects that libraries and archives maintain constantly increases. It is therefore urgent to ensure that these digital objects will remain functional, usable and intelligible in the future. But what should we preserve and how? To address this question we first summarise the discussion in previous Chapters about what a digital object is.

Understanding a Digital Object : Basic Representation Information

OAIS is not a design; its lack of specificity gives it wide applicability and great strength but it also forces implementers to make choices, among which is the level of application of the OAIS concepts. In this chapter we look particularly at Representation Information

Types of Digital Objects

It is impossible to give an exhaustive list of types of digital objects, yet it is useful to remind ourselves of at least some of the great variety that we must be able to deal with. By types we mean not just different formats, but rather different classifications.

Tools for Countering the Threats to Digital Preservation

We begin with a brief recap of the points made in Chap. 5 about the broad threats to the preservation of our digitally encoded information. Then a number of components, both infrastructure and domain dependent, are discussed and the CASPAR implementations of these are introduced. Subsequent chapters build up the details of the infrastructure and tools which indicate how these solutions could be implemented and for which strong prototypes exist at the time of writing.

Threats to Digital Preservation and Possible Solutions

There are some obvious threats to the preservation of digitally encoded information. One is what one might call “bit rot” i.e. the deterioration in our ability to read the bits in which the information is encoded. While this is fundamental, nevertheless there are an increasing number of ways to overcome this problem, the simplest of which is replication of the bits i.e. making multiple copies.

Basic Preservation Strategies

There are a number of basic preservation strategies upon which one can build more complex strategies. These are the ones which are described explicitly or implicitly by OAIS , based around ensuring that the digital object will be usable and understandable to the Designated Community . Of course one also has to maintain the trail of information to support evidence of authenticity and other PDI .

European Space Agency Testbed

The selected ESA scientific dataset consists of data from GOME (Global Ozone Monitoring Experiment), a sensor on board ESA ERS-2 (European Remote Sensing) satellite, which has been in operation since 1995.

Sharing the Effort

The concepts introduced here are aimed at providing an infrastructure which can be shared across the widest range of information. In that way we can spread the cost and effort of preservation and reduce the risk that the infrastructure upon which we would depend might itself disappear by broadening its potential support.

Cultural Heritage Testbed

The concept of cultural heritage has a wide range of applications: museums, books and libraries, paintings, etc. It also includes monuments, archaeological sites, etc. The CASPAR project we used the definition of Cultural Heritage given in the UNESCO World Heritage Convention (UNESCO, 1972)