Lou ReichNASACSC

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Problems That Need to be Solved An OAIS RM View

• Lou Reich/NASA/CSC
• 08-Nov-2005
• Digital Curation WorkshopDistributed
  Infrastructure
• London

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OAIS Archival Information Package
Archival Information Package (AIP)
Packaging Information
Package Descriptor
delimited by
derived from
e.g., How to find Content information and PDI
on some medium
e.g., Information supporting customer searches
for AIP
Preservation Description Information (PDI)
Content Information
further described by
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
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Information Package Variants

• Submission Information Package
• Negotiated between Producer and OAIS
• Sent to OAIS by a Producer
• Archival Information Package
• Information Package used for preservation
• Includes complete set of Preservation Description
  Information for the Content Information
• Dissemination Information Package
• Includes part or all of one or more Archival
  Information Packages
• Sent to a Consumer by the OAIS

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ISO Reference Model For anOpen Archival
InformationSystem (OAIS)Tutorial
Presentation Lou Reich /CSC Don Sawyer
/NASA/NSSDC June 2000
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Information Objects
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Representation Information

• The Representation Information accompanying a
  physical object like a moon rock may give
  additional meaning, as a result of some analysis,
  to the physically observable attributes of the
  rock
• The Representation Information accompanying a
  digital object, or sequence of bits, is used to
  provide additional meaning. It typically maps the
  bits into commonly recognized data types such as
  character, integer, and real and into groups of
  these data types. It associates these with
  higher level meanings which can have complex
  inter-relationships that are also described

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Recursive Nature ofRepresentation Information

• Preexisting standards that define primitive
  data-types
• Mapping rules that map those primitive data-type
  into the more complex data-type concept used by
  the Data Object
• Other semantic informa-tion that aids in the
  under-standing of the Data such as a Data
  Dictionary

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OAIS Functional Entities
GRID
SIP Submission Information Package AIP
Archival Information Package DIP Dissemination
Information Package
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Functional Entities In An OAIS

• Ingest This entity provides the services and
  functions to accept Submission Information
  Packages (SIPs) from Producers and prepare the
  contents for storage and management within the
  archive
• Archival Storage This entity provides the
  services and functions for the storage,
  maintenance and retrieval of Archival Information
  Packages
• Data Management This entity provides the
  services and functions for populating,
  maintaining, and accessing both descriptive
  information which identifies and documents
  archive holdings and internal archive
  administrative data.
• Administration This entity manages the overall
  operation of the archive system
• Preservation Planning This entity monitors the
  environment of the OAIS and provides
  recommendations to ensure that the information
  stored in the OAIS remain accessible to the
  Designated User Community over the long term even
  if the original computing environment becomes
  obsolete.
• Access This entity supports consumers in
  determining the existence, description, location
  and availability of information stored in the
  OAIS and allowing consumers to request and
  receive information products

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Preservation Planning
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Information Objects
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Representation Information

• The Representation Information accompanying a
  physical object like a moon rock may give
  additional meaning, as a result of some analysis,
  to the physically observable attributes of the
  rock
• The Representation Information accompanying a
  digital object, or sequence of bits, is used to
  provide additional meaning. It typically maps the
  bits into commonly recognized data types such as
  character, integer, and real and into groups of
  these data types. It associates these with
  higher level meanings which can have complex
  inter-relationships that are also described

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Recursive Nature ofRepresentation Information

• Preexisting standards that define primitive
  data-types
• Mapping rules that map those primitive data-type
  into the more complex data-type concept used by
  the Data Object
• Other semantic informa-tion that aids in the
  under-standing of the Data such as a Data
  Dictionary

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Analysis of Archive Issues Using OAIS RM

• Migration

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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

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Access Preservation

• Effective access to digital information requires
  the use of software
• Application Programming Interfaces (APIs) may be
  cost-effectively maintained across time by an
  OAIS when
• API is not too complex
• API is applicable to a wide variety of AIUs
• API source code may be ported to new environments
• Extensive testing is needed to ensure against
  information loss
• Preservation of executables by full emulation of
  underlying hardware is problematic
• Hard to know what is the information being
  preserved
• May not be possible to fully emulate associated
  devices

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Categories of Archive Interactions

• Independent no knowledge by one OAIS of
  Standards implemented at another
• Cooperating Potentially common submission
  standards, and common dissemination standards,
  but no common access. One archive may make
  subscription requests for key data at the
  cooperating archive
• Federated Access to all federated OAIS is
  provided through a common set of access aids that
  provide visibility into all participating OAISs.
  Global dissemination and Ingest are options
• Shared resources An OAIS in which Management has
  entered into agreements with other OAISs is to
  share resources to reduce cost. This requires
  various standards internal to the archive (such
  as ingest-storage and access-storage interface
  standards), but does not alter the communitys
  view of the archive

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Federated Archives
Local
Consumer
Dissemination Information Package
(Optional)
Access
Access
Global
Consumer
Common Catalog
Administration
Administration
OAIS 2
Ingest
Access
Access
Local
Consumer
Dissemination Information Package
(Optional)
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Levels of Autonomy in Associated Archives

• No interactions and therefore no association
• Associations that maintain your autonomy. You
  have to do certain things to participate, but you
  can leave the association without notice or
  impact to you.
• Associations that bind you by contract. To
  change the nature of this association you will
  have to re-negotiate the contract. The amount of
  autonomy retained depends on how difficult it is
  to negotiate the changes.

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Conclusions
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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