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Planning to Maximize Longevity of Digital Information
Howard Besser
UCLA School of Education & Information
http://www.gseis.ucla.edu/~howard
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Planning to Maximize Longevity of Digital Info-
Access and Preservation Why are you Managing this Information? Key Considerations for Imaging Projects Important Planning Considerations Models for Digital Collections Importance of Metadata Standards Digital Longevity Issues More Planning Issues
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Access and Preservation
_ Digitizing can serve both Access and Preservation– E.g. Access to digital surrogates saves wear & tear on
originals
_ But Digitization for Access can be quite different than Digitization for Preservation– Level of detail, scanning quality, extensiveness of
resources
– And long-term retention of digital works is still an open issue
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Why are you Managing this Information?
Organizational mission & type Users Uses
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Key Considerations for Imaging Projects-
Users' Needs Image Quality Intellectual Property Standards Topology Tools & Processes
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Key Considerations for Imaging Projects (1 of 3)
Users' Needs– Quality of Digital Surrogate– Interoperable desktop applications
Image Quality– Archival– Current online delivery
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Key Considerations for Imaging Projects (2 of 3)
Intellectual Property Standards
– Modular and Layered Architecture– Terminology– Technical imaging information
Topology
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Key Considerations for Imaging Projects (3 of 3)
Tools & Processes– Scanners– Compression techniques– Linking files– Workflow– Interoperable desktop applications
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Some nuts-and-boltsPlanning Considerations
Think about users (and potential users), uses, and type of material/collection
Scan at the highest quality that does not exceed the likely potential users/uses/material
Do not let today’s delivery limitations influence your scanning file sizes; understand the difference between digital masters and derivative files used for delivery
Many documents which appear to be bitonal actually are better represented with greyscale scans
Include color bar and ruler in the scan
Use objective measurements to determine scanner settings (do NOT attempt to make the image good on your particular monitor or use image processing to color correct)
Don’t use lossy compression Store in a common (standardized)
file format Capture as much metadata as is
reasonably possiple (including metadata about the scanning process itself)
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Why Scale is important
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Important Planning Considerations
File Formats Choosing Interoperable Systems Adhere to standards Vendors with large installed base Refreshing and/or Migration
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Key problems we’re facing
Discovery Longevity- Interoperability-
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Serious Longevity Problems
What we know from prior widespread digital file formats
Images separating from their metadata Inaccessibility of software needed to view an
image Inability to even decode the file format of an
image …return to Longevity problem later-
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Traditional Digital Library Model
DL
DL
DL
DL
useruser
search & presentation
search & presentation
search & presentation
search & presentation
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Ideal Digital Library Model
DL
DL
DL
DL
useruser
search & presentation
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For Interoperability Digital Libraries Need Standards
Descriptive Metadata for consistent description
Discovery Metadata for finding Administrative Metadata for viewing and
maintaining Structural Metadata for navigation ... Terms & Conditions Metadata for
controlling access...
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Why are Standards and Metadata consensus
important? Managing digital files over time Longevity Interoperability Veracity Recording in a consistent manner Will give vendors incentive to create
applications that support this
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Why Standards? Why do we need standards?
– To make information universally available to users– facilitate sharing and interchange of information– To preserve information (make it safe from
changes in hardware and software) Standards only work if communities widely
accept them, but they’re necessary for communities to work together
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Questions to Ask
What communities is this standard designed for? What type of information is this standard designed to
handle? What functions is this standard designed to serve? What previous standards is it built upon? Does the standard prescribe how to create new records (or
parts of records), or how to map from existing records? How far does the standard go? Semantics: Does it define
element sets? Rules? Syntax?-
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Semantics/Syntax/Structure
_ Semantics– meaning, as defined by a community to meet their particular needs
(DC)
_ Syntax– a systematic arrangement of data elements for machine processing
– facilitates the exchange and use of metadata among various applications (HTML, XML, RDF)
_ Structure– a formal arrangement of the syntax with the goal of consistent
representation of the semantics (rules defining field contents like 1/11/99)
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The Short Life of Digital Info: Digital Longevity Problems-
Disappearing Information The Viewing Problem The Scrambling Problem The Inter-relation Problem The Custodial Problem The Translation Problem
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The Viewing Problem
Digital Info requires a whole infrastructure to view it
Each piece of that infrastructure is changing at an incredibly rapid rate
How can we ever hope to deal with all the permutations and combinations
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The Scrambling Problem
Dangers from: Compression to ease storage & delivery Container Architecture to enhance digital
commerce
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The Inter-relation Problem
-Info is increasingly inter-related to other info
-How do we make our own Info persist when it points to and integrates with Info owned by others?
-What is the boundary of a set of information (or even of a digital object)?
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The Custodial Problem
How do we decide what to save? Who should save it? How should they save it?
– -methods for later access: emulation, migration, etc.
– -issues of authenticity and evidence
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The Translation Problem
Content translated into new delivery devices changes meaning– -A photo vs. a painting– -If Info is produced originally in digital form in
one encoded format, will it be the same when translated into another format?
– Behaviors
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Pieces of the Solution (1/2)
-We need to insist upon clearly readable standardized ways for digital objects to self-identify their formats
-We should discourage scrambling -We need to better understand information
inter-relates to other Info, and what constitutes “boundaries” of Info objects
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Pieces of the Solution (2/2)
-People and organizations wishing to make information persist need guidelines of how to go about doing it
-We need to better understand how translating from one storage or display format to another affects the meaning of a work
-We need to save the “behaviors” of a digital object, not just it’s “contents”
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Conceptual Approaches to Digital Preservation
_ Refreshing always necessary due to volatility of physical strata– Impact on evidential value
_ Migration -- advantages & disadvantages_ Emulation -- advantages & disadvantages
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Metadata can be the first line of defense
Can tell you– where the file is (if you can’t find the file)– where more info about the file is (if you have the
file but most other metadata has become separated)
– what the file format is– what the compression scheme is– what application program and version is needed
for the file
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Groups Working onthe Big Problem
http://sunsite.berkeley.edu/Longevity/
CPA Task Force Getty “Time & Bits” Conference & Follow-ups- Emulation experiments in US and Europe
NEDLIB, CURL, Michigan
Mellon-funded E-Journal Archive experiments
Internet Archive Long Now
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Time & Bits
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Time & Bits Participants
Steward Brand Howard Besser Brian Eno Danny Hillis Peter Lyman Brewster Kahle Kevin Kelly
Jaron Lanier Doug Carlston John Heilemann Ben Davis Margaret MacLean Bruce Sterling Paul Saffo
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Groups Working onPieces of the Big Problem
http://sunsite.berkeley.edu/Longevity/
Internet Archive Long Now Emulation experiments in US and Europe
NEDLIB, CURL, Michigan
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Journal Archiving
_ License, don’t own; may not be even able to obtain right to make archival copy
_ Increasingly no paper back-up at all_ Usually we don’t have the important
redundancy factor_ Stanford’s LOCKSS Project (Lots of Copies
Keeps Stuff Safe) and its problems (http://lockss.stanford.edu)
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Migration/Refreshing
Impact on evidential value
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More Planning Issues
_ Image Families_ Behaviors_ Persistent Identification
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Identification/Provenance (Images)-
The number of variant forms of a work can be enormous Image Families A digital image frequently has many layers of parentage Information about the parentage that can indicate the
quality and veracity of the image (Dublin Core "Source" and "Relation")
how to deal with different versions derived from the same scan or different encoding schemes
Vocabulary Standards to express this
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The number of variant forms of a work can be enormous
different views of the same object different scans of the same photo different resolutions different compression schemes different compression ratios different file storage formats different details of the same image ...
Image Families
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Identification/Provenance
how to deal with different versions (browse, hi-res, medium res) derived from the same scan or different encoding schemes (TIFF, PICT, JFIF)
Vocabulary Standards to express this– VRA Surrogate Categories– CIMI's "Image Elements”
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MOA II Behaviors
Navigation Display/Print
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MOA II Best practices
Use/Users/Collection: Benchmarking Masters vs. Derivatives Scanning- Administrative Metadata- Structural Metadata-
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To deal with Immediately
_ Persistent IDs_ Metadata
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Persistent IDs--the Problem
_ Need to separate work ID from work location
_ URNs probably won’t be ready until 2003_ Becomes a business process issue when one
organization maintains the resource and another organization references it (ie. licensed from vendors or managed by separate administrative structures)
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More Persistent IDs--the Approach for today
_ PURLs_ Handles_ HTTP redirects
_ And worry about costs now and conversion costs when URNs become feasible
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Data Set ManagementMore issues with referencing IDs
_ References for mirror sites_ References for back-up sites when main site
is down or bottle-necked_ References for off-site copies and archival
copies
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One Final Question:Who will collect the digital works of
today that should become the Special Collections of tomorrow?
_ web sites_ zines_ electronic journals_ listserve and email discussions_ drafts of works that later become famous
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Howard Besser
UCLA School of Education & Information
http://sunsite.berkeley.edu/Longevity/ http://www.gseis.ucla.edu/~howard http://sunsite.berkeley.edu/moa2 http://lockss.stanford.edu http://www.longnow.com/10klibrary/TimeBitsDisc/ http://www.archive.org/
Planning to Maximize Longevity of Digital Information
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