Introduction to the Reference Model for an Open Archival Information System (OAIS)

Introduction to the Reference Model for an Open Archival Information System (OAIS) Michael Day, Digital Curation Centre UKOLN, University of Bath [email_address] Archives and Records Management, HIST 564 Applied Communication and IT Skills, University of Liverpool, 3 December 2007

Session outline Introduction to the OAIS Model: Background Mandatory Responsibilities Functional Model (repository view) Information Model (object view) Main application areas: Trusted repositories (compliance) The analysis and comparison of repositories Informing system design Preservation metadata

OAIS background (1) Reference Model for an Open Archival Information System (OAIS) Development led by the Consultative Committee for Space Data Systems (CCSDS) Issued as CCSDS Recommendation (Blue Book) 650.0-B-1 (January 2002) Also adopted as: ISO 14721:2003 Periodic reviews (no major changes from most recent review) http://public.ccsds.org/publications/archive/650x0b1.pdf

OAIS background (2) OAIS is a reference model This is fundamental to knowing how the standard should be understood The models provide a conceptual space for informing the development of repository systems (and components), both technical and non-technical - implementation independent Some key concepts (e.g., Representation Information, Designated Community) have become fundamentally important in digital preservation discussions

OAIS purpose and scope (1) To define an Open Archival Information System The term 'open' means that the document was developed in an open way, and does not imply that access to an OAIS should be unrestricted An archive is defined as an "organization that intends to preserve information for access and use by a designated community." (p. 1-8)

OAIS purpose and scope (2) While an OAIS itself need not be permanent, the information being maintained has been deemed to need "Long Term Preservation" Long term = long enough for there to be a concern about the impact of changing technologies

OAIS purpose and scope (3) Primary focus on digital information Specific aims include: A framework for the understanding and awareness of the archival concepts needed for long term preservation (access) Terminology and concepts for describing and comparing: Architectures and operations Preservation strategies and techniques Data models

OAIS purpose and scope (4) Specific aims (continued): Consensus on elements and processes for long term preservation A foundation for other standards Applicability: Applicable to any archive, but mainly focused on organisations with responsibility for making information available for the long term Also of interest to those who create information

OAIS purpose and scope (5) Conformance: An OAIS must support the information model - but does not specify any particular method of implementation Mandatory responsibilities (section 3.1) Caveats (section 1.4): "It is assumed that implementers will use this reference model as a guide while developing a specific implementation to provide identified services and content"

OAIS purpose and scope (6) Caveats (continued): The model does not assume or endorse any specific computing platform, system environment, system design paradigm, database management system, data definition language, etc. An OAIS may provide additional services A conceptual framework to discuss and compare archives Road map for related standards (section 1.5)

OAIS definitions (1) OAIS - "An archive, consisting of an organization of people and systems, that has accepted the responsibility to preserve information and make it available for a Designated Community” Designated Community - the community of stakeholders and users that the OAIS serves Knowledge Base - a set of information, incorporated by a user or system, that allows that user or system to understand the received information

OAIS definitions (2) Information Object - Data Object + Representation Information Representation Information - any information required to render, interpret and understand digital data Information Package - Conceptual linking of Content Information + Preservation Description Information + Packaging Information (Submission, Archival and Dissemination Information Packages)

OAIS definitions (3) Preservation Description Information - information (metadata) about Provenance, Context, Reference, Fixity

OAIS high-level concepts (1) A summary of key high-level concepts that are formally modelled in section 4 Defines: The environment of an OAIS Producers, Consumers, Management Recognises that an OAIS exists within a wider context

OAIS high-level concepts (2) Definitions of information , Information Objects and their relationship with Data Objects Recognises the importance of a organisation's Knowledge Base in being able to understand information Introduces the Representation Information concept

OAIS high-level concepts (3) Definitions of Information Packages , conceptual containers of Content Information and Preservation Description Information The packaging of content is useful to support the submission of information to an OAIS or dissemination of information to Consumers Packaging Information encapsulates Content Information and Preservation Description Information, is discoverable by virtue of Descriptive Information (Figure 2-3)

OAIS high-level concepts (4) Information Package Concepts and Relationships (Figure 2-3)

OAIS high-level concepts (5) Defines Preservation Description Information Introduces Information Package variants Variants are: Submission Information Package (SIP) Archival Information Package (AIP) Dissemination Information Package (DIP) Recognises that packages will need to vary depending upon their role

OAIS external interactions High level view of the interactions in an OAIS environment Management interaction Charter and scope, Funding, Conflict resolution Producer interaction Submission agreements Consumer interaction Help desk questions, catalogue searches, ordering of information

OAIS mandatory responsibilities (1) Negotiate for and accept appropriate information from information Producers Obtain sufficient control of the information provided to the level needed to ensure Long-Term Preservation Determine, either by itself or in conjunction with other parties, which communities should become the Designated Community and, therefore, should be able to understand the information provided

OAIS mandatory responsibilities (2) Ensure that the information to be preserved is Independently Understandable to the Designated Community. In other words, the community should be able to understand the information without needing the assistance of the experts who produced the information Follow documented policies and procedures which ensure that the information is preserved against all reasonable contingencies, and which enable the information to be disseminated as authenticated copies of the original, or as traceable to the original Make the preserved information available to the Designated Community

OAIS Functional Model (1) Six entities Ingest Archival Storage Data Management Administration Preservation Planning Access Described using UML diagrams ...

OAIS Functional Model (2) OAIS Functional Entities (Figure 4-1)

OAIS Functional Entities (1) Ingest - services and functions that accept SIPs from Producers; prepares AIPs for storage, and ensures that AIPs and their supporting Descriptive Information become established within the OAIS Archival Storage - services and functions used for the storage and retrieval of AIPs

OAIS Functional Entities (2) Data Management -services and functions for populating, maintaining, and accessing a wide variety of information Administration - services and functions needed to control the operation of the other OAIS functional entities on a day-to-day basis Preservation Planning - services and functions for monitoring the OAIS environment and ensuring that content remains accessible to the Designated Community

Preservation Planning Functions

OAIS Functional Entities (3) Access - services and functions which make the archival information holdings and related services visible to Consumers

OAIS Information Objects (1) Information Object (basic concept): Data Object (bit-stream) Representation Information (permits “the full interpretation of Data Object into meaningful information”) Information Object Classes: Content Information Preservation Description Information (PDI) Packaging Information Descriptive Information

OAIS Information Objects (2) OAIS Information Object (Figure 4-10) Information Object Representation Information 1+ interpreted using 1+ Data Object interpreted using Physical Object Digital Object Bit Sequence 1+

OAIS Information Objects (3) Representation Information: Any information required to render, interpret and understand digital data (includes file formats, software, algorithms, standards, semantic information etc.) Representation Information is recursive in nature Essential that Representation Information itself is curated and preserved to maintain access to (render and interpret) digital data e.g. Format registries (GDFR, TNA's PRONOM-DROID)

OAIS Information Objects (4) OAIS Representation Information Object (Figure 4-11)

OAIS Information Packages (1) Information package: Container that encapsulates Content Information and PDI Packages for submission (SIP), archival storage (AIP) and dissemination (DIP) AIP = “... a concise way of referring to a set of information that has, in principle, all of the qualities needed for permanent, or indefinite, Long Term Preservation of a designated Information Object”

OAIS Information Packages (2) Archival Information Package (AIP): Content Information Original target of preservation Information Object (Data Object & Representation Information) Preservation Description Information (PDI) Other information (metadata) “which will allow the understanding of the Content Information over an indefinite period of time” A set of Information Objects In part based on categories discussed in CPA/RLG task force report (1996)

OAIS Information Packages (3) Preservation Description Information Reference Information Provenance Information Context Information Fixity Information PDI Preservation Description Information (Figure 4-16)

OAIS Information Packages (4) Fixity - supporting data integrity checking mechanisms Reference - for supporting identification and location over time Context - documenting the relationship of the Content Information to its environment Provenance - documents the history of the Content Information

OAIS Information Model Also defines: Archival Information Units and Archival Information Collections Recognises the complexity some some objects, addresses granularity Information Package transformations For Ingest and Access

OAIS - other perspectives Preservation Migration, e.g refreshment, replication, repackaging, transformation Preservation of look and feel (e.g., emulation, virtual machines) Archive interoperability Interaction between OAIS archives (e.g., co-operating and federated archives) Examples of existing archives

Implementation fundamentals (1) OAIS is a reference model (conceptual framework), NOT a blueprint for system design It informs the design of system architectures, the development of systems and components It provides common definitions of terms … a common language, means of making comparison But it does NOT ensure consistency or interoperability between implementations

Implementation fundamentals (2) ISO 14721:2003 Follows the Recommendation made available by the CCSDS However, earlier versions of the model made available by the CCSDS informed implementations long before its formal issue by ISO

Implementation fundamentals (3) Main areas of influence: Related standards (e.g., CCSDS Archive-Producer Interface) Standardising terminology Compliance and certification Analysis and comparison of archives Informing system design Preservation metadata

OAIS compliance (1) Many repositories or preservation tools claim OAIS influence or compliance: e.g., IBM DIAS, DSpace, OCLC Digital Archive, METS, the list is endless LOCKSS System has produced a "formal statement of conformance to ISO 14721:2003" ( lockss.stanford.edu/ ) The OAIS model's own view (OAIS 1.4): Supporting the information model (OAIS 2.2), Fulfilling the six mandatory responsibilities (OAIS 3.1)

OAIS compliance (2) OAIS Mandatory Responsibilities (recap): Negotiating and accepting information Obtaining sufficient control of the information to ensure long-term preservation Determining the "designated community" Ensuring that information is independently understandable Following documented policies and procedures Making the preserved information available

Trusted digital repositories (1) OCLC/RLG Digital Archive Attributes Working Group Trusted Digital Repositories report (2002) http://www.rlg.org/legacy/longterm/repositories.pdf Recommended the development of a process for the certification of digital repositories Audit model Standards model Built upon the OAIS model …

Trusted digital repositories (2) Identified specific attributes: Compliance with OAIS Administrative responsibility Organisational viability Financial sustainability Technological and procedural suitability System security Procedural accountability

Digital repository certification (1) RLG-NARA Task Force on Digital Repository Certification RLG and the US National Archives and Records Administration To define certification model and process Identify those things that need to be certified (attributes, processes, functions, etc.) Develop a certification process (organisational implications) Draft list of criteria published (2005) Led to TRAC (CRL & OCLC, 2007)

Digital repository certification (2) Trusted Repositories Audit & Certification (TRAC): Criteria and Checklist (March 2007) Organisational infrastructure e.g., governance, organisational structures, mandates, policy frameworks, funding systems, contracts and licenses Digital Object Management (OAIS functions) e.g., ingest, metadata, preservation strategies Technologies, Technical Infrastructure, & Security

Digital repository certification (3) Test audits (by CRL, DCC, etc.) enabled further refinement of the certification model TRAC just one of several audit and certification initiatives: German nestor initiative DRAMBORA (DCC and Digital Preservation Europe), based on risk assessment approach The aim is now to develop an ISO standard, under the general aegis of CCSDS (public wiki and mailing list)

The analysis of existing services A process that was started in the annexes to the model itself Looking at existing services and processes, mapping them to OAIS functional and information model Main uses: Identifying significant gaps Provides a common language for the comparison of archives

BADC/APS case study (1) British Atmospheric Data Centre A data centre of the Natural Environment Research Council (NERC) Evaluating the use of the CCLRC's Atlas Petabyte Storage (APS) Service for long-term data storage Mapping OAIS to combined BADC/APS BADC responsible for Ingest and Access APS responsible for Archival Storage Jointly responsible for Data Management and Administration

BADC/APS case study (2) Application of OAIS revealed: Feedback on how well the BADC/APS fulfilled OAIS mandatory responsibilities Revealed that AIP needed better definition Weaknesses identified with the Preservation Planning role, e.g. little explicit monitoring of technology or of the Designated Community OAIS helps to identify limitations For more details, see: Corney, et al . (2004) http://www.allhands.org.uk/2004/proceedings/papers/156.pdf

UKDA and TNA case study (1) Project funded by the UK Joint Information Systems Committee (JISC) Partners: UK Data Archive The National Archives Aimed to map UKDA and TNA to OAIS functional and information models, a "use case" for compliance Beedham, et al ., Assessment of UKDA and TNA Compliance with OAIS and METS Standards (2005)

UKDA and TNA case study (2) Conclusions (1): Noted that there was no existing methodology for testing OAIS compliance Recommended the production of guidelines or manual The six OAIS Mandatory Responsibilities are carried out by almost any well-established archive

UKDA and TNA case study (3) Conclusions (2): The OAIS Designated Community concept assumes a identifiable and relatively homogenous user community; this was not the case for either UKDA or TNA The relationship between AIPs and DIPs needed clarification The OAIS Administration function may be difficult for small archives to fulfil adequately

UKDA and TNA case study (3) Conclusions (3): Model not scalable - report proposes an 'OAIS Lite' Information categories (e.g. PDI) are too general to allow mapping of metadata elements from other schemas (p. 70) But ... the use of OAIS terminology was useful to support communication between UKDA and TNA

Informing system design (1) OAIS is not a blueprint for system design "It is assumed that implementers will use this reference model as a guide while developing a specific implementation to provide identified services and content" (OAIS 1.4) But it has been used to inform the design of systems This can be difficult because the model does not generally distinguish between management and technical processes

Informing system design (2) Examples: Systems: IBM DIAS (used by Koninklijke Bibliotheek in e-Depot, Deutsche national Bibliothek in KOPAL) OCLC Digital Archive Service aDORe (Los Alamos National Laboratory) Stanford Digital Repository - preservation not main focus MathArc (Cornell UL and SUB Göttingen)

Informing system design (3) Examples (continued) Tools: Harvard University Library XML-based Submission Information Package for e-journal content Repository software: DSpace, FEDORA, … DCC Representation Information Repository and Registry

Informing system design (4) A basis for domain-specific modelling: InterPARES project Preservation Task Force's " Preserve Electronic Records model" Formally modelled the specific processes and functions involved with preserving electronic records Developed "… a specification of an OAIS for the specific classes of information objects comprising electronic records and archival aggregates of such records" http://www.interpares.org/

Informing system design (5) Research projects: OAIS is the “guiding principle” of CASPAR (specifically the Representation Information concept) CASPAR Conceptual model Representation Information registries and repositories

Preservation metadata (1) Metadata: Data about data Structured information about objects that supports various types of activity: discovery, retrieval, management, etc. Can be a problematic concept Preservation metadata The information a repository uses to support the digital preservation process (PREMIS WG) OAIS Information Model influenced PREMIS

Preservation metadata (2) A number of different initiatives and standards: Reflects different professional perspectives The archives and records professions focus on traditional archival principles, e.g. the emerging ISO 23081 (Metadata for records) family of standards Other domains largely focused on use and reuse, e.g. of research data, multimedia content, digitised text and images PREMIS Data Dictionary focused on 'core' preservation requirements

Preservation metadata (3) PREMIS (Preservation Metadata: Implementation Strategies) Data Dictionary Cross-domain approach, but broad digital library influences Based on older initiatives that were more explicitly based on OAIS Information Model categories Identification of 'core' metadata to support preservation Based on its own data model

Preservation metadata (4) OAIS Information Model Divides the information needed to support preservation into two categories Representation Information (key concept) Preservation Description Information Is this metadata? Some OAIS advocates claim that focus on Representation Information is the only approach that will work for research data Much still to be resolved in this area

Summary (1) OAIS is a well established standard: Standardising the terminology used in digital preservation process The analysis and comparison of repositories (and repository processes) Informing the design of systems (and tools) Informing the development of certification criteria Informing the design and development of preservation metadata standards

Summary (2) However ... Still some uncertainty about what OAIS 'conformance' means There remains the question whether the standard is applicable in all domains Archivists involved in the initial development process, but many others feel that it doesn't adequately represent the archival perspective OAIS is just a starting point

Further reading Reference Model for an Open Archival Information System (OAIS) , CCSDS 650.0-B-1 (2002): http://public.ccsds.org/publications/archive/650x0b1.pdf DPC Technology Watch Report on the OAIS model by Brian Lavoie (2004): http://www.dpconline.org/docs/lavoie_OAIS.pdf Assessment of UKDA and TNA Compliance with OAIS and METS standards by H. Beedham, et al ., (2005): http://www.data-archive.ac.uk/news/publications/oaismets.pdf Trusted Repositories Audit & Certification (2007): http://www.crl.edu/PDF/trac.pdf DRAMBORA Digital Repository Audit Method Based on Risk Assessment (2007): http://www.repositoryaudit.eu/ nestor Catalogue of Criteria for Trusted Digital Repositories (2006): urn:nbn:de:0008-2006060703

Acknowledgements UKOLN is funded by the Museums, Libraries and Archives Council, the Joint Information Systems Committee (JISC) of the UK higher and further education funding councils, as well as by project funding from the JISC, the European Union, and other sources. UKOLN also receives support from the University of Bath, where it is based: http://www.ukoln.ac.uk/ The Digital Curation Centre is funded by the Joint Information Systems Committee and the UK Research Councils' e-Science Core Programme: http://www.dcc.ac.uk/

Introduction to the Reference Model for an Open Archival Information System (OAIS)

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