M-1 ISO “Reference Model For an Open Archival Information System (OAIS)” ISO “Reference Model For an Open Archival Information System (OAIS)” Presentation to USDA Digital Publications Preservation Steering Committee Don Sawyer NASA/NSSDC/NOST February 19, 1999

M-2 Outline of Talk Getting started Reference Model overview Digital Archive Directions (DADs) workshop Evolving the model

M-3 NASA Role National Space Science Data Center — NASA’s first digital archive — Experienced many technology changes since 1966 Consultative Committee for Space Data Systems — International group of space agencies — Developed variety of science discipline- independent standards — Became working body for an ISO TC 20/ SC 13 about 1990 TC20: Aircraft and Space Vehicles SC13: Space Data and Information Transfer Systems

M-4 Initial Archive Standards Proposal ISO suggested that SC 13 should develop archive standards –Address data used in conjunction with space missions –Address intermediate and indefinite long term storage of digital data

M-5 Response Response to Consultative Committee for Space Data Systems (CCSDS) and ISO TC 20/SC 13 –No framework widely recognized for developing specific digital archive standards –Begin by developing a ‘Reference Model’ to establish common terms and concepts –Ensure broad participation, including traditional archives (Not restricted to space communities; all participation is welcome!) –Focus on data in electronic forms, but recognize that other forms exist in most archives –Follow up with additional archive standards efforts as appropriate

M-6 Getting Started First open US workshop held October 1995 — Variety of government, academic, and industry participation, including National Archives — Active US working group was formed US workgroup activities are fully open — New participants always welcome — Plans, minutes, drafts available from Web Broad international workshops also held — Britain and France Issue resolution at CCSDS international workshops

M-7 Results Reference Model targeted to several categories of reader — Archive designers — Archive users — Archive managers, to clarify digital preservation issues and assist in securing appropriate resources — Standards developers Adopting terminology that crosses various disciplines — Traditional archivists — Scientific data centers — Digital libraries Getting favorable comments wherever exposed

M-8 Reference Model for an Open Archival Information System

M-9 Open Archival Information System (OAIS) Open –Reference Model standard(s) are developed using a public process and are freely available Information –Any type of knowledge that can be exchanged –Independent of the forms (i.e., physical or digital) used to represent the information –Data are the representation forms of information Archival Information System –Hardware, software, and people who are responsible for the acquisition, preservation and dissemination of the information –Additional OAIS responsibilities are identified later and are more fully defined in the Reference Model document

M-10 Document Organization Introduction –Purpose and Scope, Applicability, Rationale, Road Map for Future Work, Document Structure, and Definitions of Terms OAIS Concepts –High level view of OAIS functionality and information models –OAIS external environment –Minimum responsibilities to become an “OAIS” Detailed Models –Functional model descriptions and information model perspectives Migration perspectives –Media migration, compression, and format conversions Archive Interoperability –Criteria to distinguish types of cooperation among archives Annexes –Scenarios of existing archives, compatibility with other standards

M-11 Purpose, Scope, and Applicability Framework for understanding and applying concepts needed for long-term digital information preservation –Long-term is long enough to be concerned about changing technologies –Starting point for model addressing non-digital information Provides set of minimal responsibilities to distinguish an OAIS from other uses of ‘archive’ Framework for comparing architectures and operations of existing and future archives Basis for development of additional related standards Addresses a full range of archival functions Applicable to all long-term archives and those organizations and individuals dealing with information that may need long- term preservation Does NOT specify any implementation

M-12 Model View of an OAIS’s Environment OAIS (archive) Management Producer Consumer Producer is the role played by those persons, or client systems, who provide the information to be preserved Management is the role played by those who set overall OAIS policy as one component in a broader policy domain Consumer is the role played by those persons, or client systems, who interact with OAIS services to find and acquire preserved information of interest

M-13 OAIS Information Definition Information is defined as any type of knowledge that can be exchanged, and this information is always expressed (i.e., represented) by some type of data In general, it can be said that “Data interpreted using its Representation Information yields Information” In order for this Information Object to be successfully preserved, it is critical for an archive to clearly identify and understand the Data Object and its associated Representation Information Data Object Interpreted Using its Representation Information Yields Information Object

M-14 Information Package Definition An Information Package is a conceptual container of two types of information called Content Information and Preservation Description Information (PDI) Preservation Description Information Content Information

M-15 Producer Consumer Submission Information Packages Dissemination Information Packages queries query response orders OAIS Archival Information Packages Legend = Entity Information Package Data Object = Data Flow = External Data Flow Diagram

M-16 Negotiates and accepts Information Packages from information producers Obtains sufficient control to ensure long-term preservation Determines which communities (designated) need to be able to understand the preserved information Ensures the information to be preserved is independently understandable to the Designated Communities Follows documented policies and procedures which ensure the information is preserved against all reasonable contingencies Makes the preserved information available to the Designated Communities in forms understandable to those communities OAIS Responsibilities

M-17 OAIS Functional Entities SIP = Submission Information Package AIP = Archival Information Package DIP = Dissemination Information Package SIP Descriptive Info. AIP DIP Administration PRODUCERPRODUCER CONSUMERCONSUMER Requests other information MANAGEMENT Ingest Access Data Management Archival Storage Descriptive Info.

M-18 Archival Information Package (AIP) Content Information Preservation Description Information (PDI) e.g., Hardcopy document Document as an electronic file together with its format description Scientific data set consisting of images and text in three electronic files together with format descriptions e.g., How the Content Information came into being, who has held it, how it relates to other information, and how its integrity is assured OAIS Archival Information Package Packaging Information Package Descriptor further described by delimited by derived from e.g., How to find Content information and PDI on some medium e.g., Information supporting customer searches for AIP

M-19 Content Information Content Information Representation Information Data Object Physical Object Digital Object interpreted using 1+ Bit Sequence interpreted using

M-20 Preservation Description Information Provenance Information –Describes the source of Content Information, who has had custody of it, what is its history Context Information –Describes how the Content Information relates to other information outside the Information Package Reference Information –Provides one or more identifiers, or systems of identifiers, by which the Content Information may be uniquely identified Fixity Information –Protects the Content Information from undocumented alteration

M-21 Digital Migration Digital Migration is defined to be the transfer of digital information, while intending to preserve it, within the OAIS. Focus on preservation of the full information content New information implementation replaces the old OAIS has full control and responsibility over all aspects of the transfer Three major motivators are seen to drive Digital Migrations of Archival Information Packages within an OAIS: Media Decay Increased Cost Effectiveness New Consumer Service Requirements

M-22 Digital Migration Approaches Four primary types of digital migration in response to motivators, ordered by increasing risk of information loss: — Refreshment Media replacement with no bit changes — Replication No change to Packaging Information or Content Information bits — Repackaging Some bit changes in Packaging Information — Transformation Reversible: Bit changes in Content Information are reversible by an algorithm Non-reversible: Bit changes in Content Information are not reversible by an algorithm

M-23 Archive Interoperability Users of multiple OAIS archives have reasons to wish for some uniformity or cooperation among the OAISs. OAIS associations can be categorized technically by both external and internal factors. — External factors include characteristics of the Producer and Consumer communities — Internal factors could be include common implementations of the information models or multi- archive sharing of one or more of the functional areas. Four categories of archive association are defined — Independent — Cooperating — Federated — Shared Resources

M-24 Federated Archives Local Consumer Local Consumer Global Consumer Dissemination Information Package (Optional) Dissemination Information Package (Optional) Administration Common Catalog Access IngestAccess OAIS 1 Administration IngestAccess OAIS 2 Administration

M-25 Reference Model Summary Reference model is to be applicable to all digital archives, and their Producers and Consumers Identifies a minimum set of responsibilities for an archive to claim it is an OAIS Establishes common terms and concepts for comparing implementations, but does not specify an implementation Provides detailed models of both archival functions and archival information Discusses OAIS information migration and interoperability among OAISs

M-26 Reference Model Acceptance Reference model has been getting good reviews — Society of American Archivists 1997 annual meeting — NAGARA 1998 Annual Meeting — Various international conferences Major context for June 1998 Digital Archive Directions (DADs) workshop hosted by NARA — Attended by representatives of international and US national archives, science data centers, digital libraries, and academic institutions — Provided strong support for model and offered improvements

M-27 DADs Workshop Recommendations Working groups identified several ‘best practices’ and standards desired, including: — Recommended data ingest methodology — Best practices for digitizing analogue data — Best practices for media selection, testing and usage — Best practices for error control through the archive — Archival Submission Information Package standard — Consumer Archive Interface standard — Unique Archival Information Package Identifier standard — AIP Content Layered Model and Standard APIs report Plenary recommended a coordination function be established — Promote the reference model — Promote coordination of work on best practices and standards — Promote development of an archive accreditation method

M-28 Evolving the Reference Model Ultimate success of OAIS Reference Model effort depends on obtaining adequate review and comment Reference Model Red Book/ISO Draft International Standard (DIS) expected June 1999 — Current version is White Book 4.0, available under Reference Materials heading, at: — Comments are actively solicited — Most productive if received by April 15, 1999 — Send to