Saturday, February 07, 2015

Digital Preservation Coalition publishes ‘OAIS Introductory Guide (2nd Edition)’ Technology Watch Report

Digital Preservation Coalition publishes ‘OAIS Introductory Guide (2nd Edition)’ Technology Watch Report. Brian Lavoie.  Digital Preservation Coalition. Watch Report. October, 2014. [PDF]

The report describes the OAIS, its core principles and functional elements, as well as the information model which support long-term preservation, access and understandability of data. The OAIS reference model was approved in 2002 and revised and updated in 2012. Perhaps “the most important achievement of the OAIS is that it has become almost universally accepted as the lingua franca of digital preservation”.

The central concept in the reference model is that of an open archival information system. An OAIS-type archive must meet a set of six minimum responsibilities to do with the ingest, preservation, and dissemination of archived materials: Ingest, Archival Storage, Data Management, Preservation Planning, Access, and Administration. There are also Common Services, which consist of basic computing and networking resources.

An OAIS-type archive references three types of entities: Management, Producer, and Consumer, which includes the Designated Community: consumers expected to independently understand the archived information in the form in which it is preserved and made available by the OAIS. This is a  framework to encourage dialogue and collaboration among participants in standards-building activities, as well as identifying areas most likely to benefit from standards development.

An OAIS-type archive is expected to:
  • Negotiate for and accept appropriate information from information producers;
  • Obtain sufficient control of the information in order to meet long-term preservation objectives;
  • Determine the scope of the archive’s user community;
  • Ensure the preserved information is independently understandable to the user community
  • Follow documented policies and procedures to ensure the information is preserved against all reasonable contingencies
  • Make the preserved information available to the user community, and enable dissemination of authenticated
An OAIS should be committed to making the contents of its archival store available to its intended user community, through access mechanisms and services which support users’ needs and requirements. Such requirements may include preferred medium, access channels, and any access restrictions should be clearly documented.

 The OAIS information model is built around the concept of an information package, which includes: the Submission Information Package, the Archival Information Package, and the Dissemination Information Package. Preservation requires metadata to support and document the OAIS’s preservation processes, called Preservation Description Information, which ‘is specifically focused on describing the past and present states of the Content Information, ensuring that it is uniquely identifiable, and ensuring it has not been unknowingly altered’. The information consists of:
  • Reference Information (identifiers)
  • Context Information (describes relationships among information and objects)
  • Provenance Information (history of the content over time)
  • Fixity Information (verifying authenticity)
  • Access Rights Information (conditions or restrictions)
OAIS is a model and not an implementation. It does not address system architectures, storage or processing technologies, database design, computing platforms, or other technical details of setting up a functioning archival system. But it has been used as a foundation or starting point. Efforts, such as TRAC, have been made to put the attributes of a trusted digital archive into a ‘checklist’ that could be used to support a certification process. PREMIS is a preservation metadata initiative that has emerged as the de facto standard. METS, and XML based  document form, has become widely used for encoding OAIS archival information packages.

The ‘OAIS reference model provides a solid theoretical basis for digital preservation efforts, though theory and practice can sometimes have an uneasy fit.’

No comments: