Reference Model for an Open Archival Information System (OAIS) - Comments from the National Library of Australia

6 June 2000

This document contains a set of comments from the National Library of Australia on the Reference Model for an Open Archival Information System (OAIS).

The document was updated on 13 June 2000 to include a link to the NEDLIB Project contribution to the review of OAIS (NEDLIB Comments).

Background

The OAIS Reference Model is a draft recommendation of the Consultative Committee for Space Data Systems. The CCSDS is an organisation established in 1982 by member space agencies, which meets periodically to address data systems problems that are common to all participants and to formulate technical solutions. The CSIRO is an Observer Agency.

In 1990, CCSDS entered into a cooperative agreement with ISO Technical Committee 20 (aircraft and space vehicles), Subcommittee 13 (space data and information transfer systems) to coordinate the development of standards for the long term storage of digital data. The OAIS Reference Model is the first outcome of this agreement. While the OAIS Reference Model has been developed within the space data community, it is widely applicable to other types of archives. The report of the Research Libraries Group Task Force on Archiving of Digital Information, Preserving Digital Information (RLG), was an informative reference for the model.

A useful overview of the model was recently published by Brian Lavoie in the OCLC Newsletter (Lavoie).

The National Library of Australia became interested in the OAIS Reference Model as a result of work to specify requirements for a system to manage the PANDORA Archive of Australian Internet publications (DSP). While the Library's requirements are not based directly on the OAIS Reference Model, it was used as a check list to ensure that all functions, entities and relationships were included. The National Library of Australia has also formed links with other national libraries and research organisations around the world engaged in similar work, including the NEDLIB and Cedars projects.

The NEDLIB Project has also contributed to the review of the OAIS Reference Model (NEDLIB Comments).

Comments

We have found the OAIS Reference Model to be an extremely valuable framework for the development of requirements for our digital archive. In its current form, it has reached a high level of maturity. The concepts are well developed and requirements from a range of different communities are addressed. In practice, the level of effort needed to understand the model is significant and many users of the model may not read beyond the first three sections. Section 1.6.1 acknowledges this and provides a useful guide to readers. However, there are some important concepts that are only develped fully well into the model. For this reason, we would recommend a last check to align the definitions in Section 1.7.2 carefully with the full model, particularly where there are multiple concepts with similar sounding definitions. Examples where clarification would help are:

This having been said, we have found the OAIS Reference Model sufficiently flexible to handle the full range of Content Information types that we have identified for inclusion in the PANDORA Archive.

Need for a Preservation function

Our main concern with the model in its current form is the need to incorporate a Preservation function. The Nedlib Project also found the need to extend the model in this area in its Data/Functional Model for a DSEP (DSEP), which otherwise follows the OAIS Reference Model. There are other functional areas essential to deposit libraries building selective archives of electronic publications - for example, Selection , Evaluation and Collection of Content Information - that we accept as falling outside the scope of the model. However, we see the preservation function is a core responsibility of an OAIS. Section 5 currently goes some way towards addressing this isssue but it still implies that Preservation is not a core function of an OAIS or that it is somehow already addressed within the model. The new Preservation function needs to be separate from Archival Storage to support Digital Migrations that change the Content Information and therefore create a new Archival Information Package. Work in this area would assist in identifying more fully the information needed to support the Preservation function, either as Preservation Description Information or as Data Management Data (see below). Currently, the sections on Data Management Data are most developed in relation to information needed to support the Access function.

Handling old versions

Sections 5.1 and 5.1.3.4 state that the outcome of Digital Migration in an OAIS is a full replacement for the Archival Information Package that is undergoing transfer. We understand that by this is meant that the transfer process should result in minimum information loss, not that the Archival Information Package undergoing transfer is necessarily discarded. In cases where a new Archival Information Package is created, our archival policy requires the source AIP to be retained. We might transform an Archival Information Package from one file type to another to enhance current access while retaining the source copy as an archival master. At a later stage, the replacement copy might be used as the source of another transformation; or we might return to the archival master for the new transformation. It would be useful if this requirement to retain source AIPs was clarified in Section 5.1.3.4.

Handling process history information

Section 5.1.4 states that, when an Archival Information Package undergoes a Digital Migration that involves Transformation, the process history is recorded in the Preservation Description Information of the new Archival Information Package. In contrast, when an Archival Information Package undergoes a Digital Migration that does not involve Transformation, the Preservation Description Information does not get updated, but OAIS still tracks such migration. Presumably, this information would be stored as Data Management Data. If so, this means that process history information is managed separately depending on the process performed. We are not sure if this is an issue, but it is an area where we have found it difficult to make a clean mapping between our model for the PANDORA Archive and the OAIS Reference Model.

It would assist if examples of this kind of Data Management Data were included in Sections 1.7.2 and 4.2.3.

Handling software

Our understanding is not yet well advanced in relation to software required for accessing a particular Archival Information Package and how this is handled in the model. The model makes it clear that Representation Information cannot depend on referencing software, as this would not completely specify the Representation Network needing to be in place for ongoing access to a given Archival Information Package. However, we also assume that, at a given time, an OAIS will use software as part of the Access function to provide current access. We assume that software is another type of Information Object, that it might be treated as an Archival Information Package in its own right, and that it might be part of a set of operations invoked during Access. We are not sure where information about the software needing to be invoked in order to support current access to a given Archival Information Package would be managed.

References

Cedars

University of Leeds. The Cedars Project: CURL Exemplars for Digital ARchiveS. Online. Available: http://www.leeds.ac.uk/cedars/. 2000-05-18.

DSP

National Library of Australia. Digital Services Project. Online. Available: http://www.nla.gov.au/dsp/. 2000-05-18.

DSEP

Koninklijke Bibliotheek - National Library of the Netherlands. Data/Functional Model for a DSEP. Nedlib Gen-264. 23 July 1999. Online. PDF. Available: http://www.kb.nl/coop/nedlib/meetings/paris/GEN-264.pdf. 2000_05-18.

NEDLIB

Koninklijke Bibliotheek - National Library of the Netherlands. Nedlib: Networked European Deposit Library. Online. Available: http://www.konbib.nl/nedlib/. 2000-05-18.

NEDLIB Comments

Koninklijke Bibliotheek - National Library of the Netherlands. NEDLIB Contribution to the Review of OAIS. June 2000. Online. Available; http://www.kb.nl/coop/nedlib/results/OAISreviewbyNEDLIB.html.

Lavoie

Lavoie, Brian. "Meeting the challenges of digital preservation: the OAIS reference model". OCLC Newsletter. No. 243. January/February 2000. Pages 26-30. Online. PDF. Available: http://www2.oclc.org/oclc/pdf/news243.pdf. 2000-05-18.

OAIS

Consultative Committee for Space Data Systems. Reference Model for an Open Archival Information System (OAIS): Draft Recommendation for Space Data System Standards. CCSDS 650.0-R-1. Red Book. May 1999. Online. PDF. Available: http://ftp.ccsds.org/ccsds/documents/pdf/CCSDS-650.0-R-1.pdf. 2000-05-18.

RLG

Research Libraries Group Task Force on Archiving of Digital Information. Preserving Digital Information. May 1996. Online. PDF. Available: ftp://ftp.rlg.org/pub/archtf/final-report.pdf. 2000-05-18.