Title: The%20OAIS%20Reference%20Model:%20an%20introduction
1The OAIS Reference Model an introduction
- Michael Day,Digital Curation CentreUKOLN,
University of Bathm.day_at_ukoln.ac.uk - DLF and Reference Models meeting, One Great
George Street, London, 25 January 2006
2Presentation outline
- The OAIS Reference Model
- Background
- Definitions, high level concepts, mandatory
responsibilities - Functional Model
- Information Model
- Implementing the model
- Preservation metadata
- Informing system design
- Conformance and certification
3OAIS background
- 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 147212003
- http//public.ccsds.org/publications/archive/650x
0b1.pdf
4OAIS definitions
- Provides definitions of terms that need to have
well-defined meanings, e.g. - Archival Storage, Content Data Object, Designated
Community (key term), Ingest, Metadata,
Representation Information, etc. - 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" (OAIS
1.7.2)
5OAIS high level concepts (1)
- The environment of an OAIS (Producers, Consumers,
Management) - Definitions of information, Information Objects
and their relationship with Data Objects - Definitions of Information Packages, conceptual
containers of Content Information and
Preservation Description Information
6OAIS high level concepts (2)
- Information Package Concepts and Relationships
(Figure 2-3)
7OAIS mandatory responsibilities
- 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, i.e. without the assistance of
those who produced it - Following documented policies and procedures
- Making the preserved information available
8OAIS Functional Model (1)
- Six entities
- Ingest
- Archival Storage
- Data Management
- Administration
- Preservation Planning
- Access
- Described using UML diagrams
9OAIS Functional Model (2)
PRODUCER
CONSUMER
Preservation Planning
DIP
Descriptive info.
Access
Descriptive info.
queries
Data Management
SIP
result sets
Ingest
orders
Archival Storage
SIP
AIP
AIP
SIP
DIP
Administration
MANAGEMENT
OAIS Functional Entities (Figure 4-1)
10OAIS Information Model (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
11OAIS Information Model (2)
- 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
12OAIS Information Model (3)
- 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
- Based on categories discussed in CPA/RLG report
Preserving Digital Information (1996)
13OAIS Information Model (4)
Preservation Description Information
Reference Information
Provenance Information
Context Information
Fixity Information
PDI Preservation Description Information (Figure
4-16)
14OAIS Information Model (5)
- Also defines
- Archival Information Units and Archival
Information Collections - Information Package transformations, e.g. for
Ingest and Access - Preservation perspectives
- Migration, e.g refreshment, replication,
repackaging, transformation - Preservation of look and feel (e.g., emulation,
virtual machines) - Archive interoperability, e.g. federation
15Implementing OAIS (1)
- Fundamentals
- 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
16Implementing OAIS (2)
- ISO 147212003, published in early 2003 - follows
the text made available by the CCSDS - However, the earlier versions of the model made
available by the CCSDS informed implementations
long before then - Three broad areas of influence
- Preservation metadata schemas
- Architecture and system design
- Conformance criteria for repositories
17Implementing OAIS - metadata
- The OAIS Information Model has been used to
inform the development of many preservation
metadata schemas, e.g. - Draft schemas developed by the National Library
of Australia, Cedars project, NEDLIB project,
etc. - METS (Metadata Encoding and Transmission
Standard) interpreted as an implementation of the
OAIS Information Package concept - Information Model explicitly used for the
structure of the OCLC/RLG Metadata Framework
(2002) - Different approach taken by PREMIS Data
Dictionary (2005)
18Implementing OAIS - systems (1)
- Two main uses (to date)
- To analyse existing preservation management
practices - Helps with the comparison of repositories and the
identification of important gaps - Studies of BADC, UK Data Archive,
- "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) - Examples
19Implementing OAIS - systems (2)
- Stanford Digital Repository
- "OAIS-compliant" system for managing digitised
objects - OCLC Digital Archive Service
- Subscription service claimed to be "Based on
OAIS" - Harvard University Library
- XML-based Submission Information Package for
e-journals - Cedars project
- Distributed archive prototype - Representation
nets - DCC RI Registry/Repository, DSpace, KB e-Depot,
20Implementing OAIS - conformance (1)
- Many repositories or preservation tools claim
OAIS compliance - e.g., DSpace, OCLC Digital Archive, METS
- LOCKSS System has produced a "formal statement of
conformance to ISO 147212003" (lockss.stanford.ed
u/) - The OAIS model claims to be a basis for
conformance (OAIS 1.4), e.g. - Supporting the information model (OAIS 2.2),
- Fulfilling mandatory responsibilities (OAIS 3.1)
21Implementing OAIS - conformance (2)
- OAIS Mandatory Responsibilities
- 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
22Implementing OAIS - conformance (3)
- OCLC/RLG Digital Archive Attributes Working Group
- Trusted Digital Repositories report (2002)
- Recommended the development of a process for the
certification of digital repositories - Audit model
- Standards model
- Goes well beyond OAIS mandatory responsibilities
- e.g., administrative responsibility,
organisational viability, financial
sustainability, system security, etc.
23Implementing OAIS - conformance (4)
- RLG-NARA Task Force on Digital Repository
Certification - Research Libraries Group (RLG) and the US
National Archives and Records Administration
(NARA). - 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 checklist for self certification (August
2005), being tested by various projects in US,
also by DCC
24Some personal comments (1)
- Conformance with the OAIS model is often cited by
digital preservation efforts (e.g. DSpace, METS)
- but, given the nature of the model, can these
claims be meaningful? - At present, the model is best seen as a means of
comparison between repositories, or a means of
judging progress (e.g. Data Archive, BADC) - Sometimes interpreters of the model seem
reluctant to acknowledge that it could be improved
25Some personal comments (2)
- OAIS mandatory responsibilities do not seem to
identify all relevant criteria - but, together
with the additional requirements now developed by
the RLG-NARA Task Force, could be used in the
future as a starting point for conformance - There may be a need for periodic revision, some
clarification of definitions, possibly some
comment from the archives world (who can be very
critical of the metadata frameworks based on it)
26Key links
- OAIS Reference Model http//public.ccsds.org/publ
ications/archive/650x0b1.pdf - DPC Technology Watch Report on OAIS model by
Brian Lavoie (OCLC Research)http//www.dpconline
.org/ - RLG/NARA Task Force on Digital Repository
Certificationhttp//www.rlg.org/
27Reference models for digital libraries - a brief
overview of recent DELOS activities
- Michael Day,Digital Curation CentreUKOLN,
University of Bathm.day_at_ukoln.ac.uk - DLF and Reference Models meeting, One Great
George Street, London, 25 January 2006
28DELOS/NSF Working Group
- DELOS/NSF working group on Reference Models for
Digital Libraries - WG co-ordinated by José Borbinha and John Kunze
- Final Report (July 2003) looked at actors and
roles - Actor "a person, organization, or automaton
playing a role in the production, dissemination,
management or use of digital information" - http//www.dli2.nsf.gov/intl.html
29DLMS Reference Model (1)
- Reference Model for Digital Library Management
Systems - DELOS Network of Excellence on Digital Libraries
(IST Project) - Work being undertaken by DELOS Digital Library
Architecture cluster (WP1) - Partners ISTI-CNR, University of Athens,
University of Glasgow, UMIT - Claim that they will establish liaisons with
other DELOS partners and at international level - Very little detail on this to date
30DLMS Reference Model (2)
- Brief overview
- Mainly concerned with the heterogeneity of
existing DL systems, i.e. getting DLs and DL
components to work together - There is a " lack of any agreement on the
foundations for Digital Library Management
Systems - Project (one of many in JPA2) will define a
formal and conceptual framework - From three perspectives end users, system
administrators, software engineers - Some detail at http//www.delos.info/reports/Res
earch_Activities_2005.pdf
31DLMS Reference Model (3)
- Highest Level Concepts
- Source Castelli, et al. (2005) in DELOS
Research Activities 2005
32DLMS Reference Model (4)
- DELOS brainstorming meeting on the European
Digital Library - December 2005
- Recommended the establishment of "a unified
service-oriented framework for all digital
library projects sponsored by the European
Commission " (Recommendation 14) - This " lists mandatory and optional DL
components describes the functionality of these
components within a conceptual framework" - More information http//www.delos.info/eventlist/
DELOSBrainstormingReport_Final.pdf
33Links
- DELOS Research Activities 2005
http//www.delos.info/reports/Research_Activities_
2005.pdf - DELOS Recommendations and Observations for a
European digital Library (EDL)
http//www.delos.info/eventlist/DELOSBrainstorming
Report_Final.pdf - DELOS Digital Library Architecture
http//ii.umit.at/research/delos_website