Digital Preservation Seminar: Overview of TopicIntroDigital Longevity ProblemPreservation in the Digital AgeScope of the ProblemTechnical Dimensions of the ProblemInadequacy of Most Proposed ApproachesCriteria for an Ideal SolutionEmulation Solution: “Annotate, Encapsulate, Transliterate, and Emulate”Emulation: DiagramEmulation in a NutshellResearch Required for the Emulation ApproachCitations and Related Resources: Other Views, Pro & ConCurrent State of Affairs: 4 Years LaterConclusion22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 1Digital Preservation Seminar: Overview of Topic•Topic Article:Avoiding Technological Quicksand: Finding a Viable Technical Foundation for Digital Preservation by Jeff Rothenberg. Published in CLIR (Council on Library & Information Resources), January 1999 •Presentation Approach:–Summary of Rothenberg’s Report–Discussion of some related resources•What his sources said•Controversies raised and other opinions–Current State of Affairs•Report dates from 1999: what’s happened since then?Note: •Slide titles 2 through 10 are the section headings of the main article•Unless otherwise noted, quotes are excerpted directly from the article22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 2Intro•Rothenberg’s ironic observation: “Digital Information lasts forever (or 5 years, whichever comes first)”•Focus is preservation of digital objects (vs. digital preservation of non-digital objects)•Discusses pitfalls of various solutions (ex: print-outs, Standards, sw/hw ‘museums’, continual migration )•Proposes emulation as best long-term solution22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 3Digital Longevity Problem•Digital media has relatively short lifespan•A Perfect copy does not mean a usable copy•Obsolescence of hardware and software is a major issue•The right to keep, make, share copies is equally problematic•Costs in terms of physical resources - including manpower - are high22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 4Preservation in the Digital Age•Digital objects must retain their digital essence–Machine readable, copy-able, distributable, functional, etc.•Converting digital documents to paper does not solve problem–Item may have non-printable, interactive properties–No longer retains digital essence (see above)•What is an original?–For paper, meaning is clear–For digital objects, it does not mean keeping the original hard drive, for example–Main purpose is to guarantee fidelity to the “First One”.22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 5Scope of the Problem•Information loss has become an accepted cost of technical evolution•Migration to new systems often results in ‘orphaning’ of data (the ‘really old’ stuff is not ‘worth the effort’)•Today’s ‘backups’ & archives become tomorrow’s orphans–Long-term survivability is the big problem–Multi-media and hypermedia-based digital items are as vulnerable as text-based documents, possibly more so22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 6Technical Dimensions of the Problem•Physical issues: decay, obsolescence, corruption–Media vulnerability examples -> CD examples (commercial, home-made) -> disk & tape formats•Software dependence“digital documents exist only by virtue of software that understands how to access and display them”–Obsolescence a factor – “version” compatibilities, etc.–OS dependence–Co-dependence on hardware factors•Other issues–Cost, IPR, authentication–Anthropological considerationsMarshall McLuhan: “The medium is the message.”22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 7Inadequacy of Most Proposed Approaches4 categories, each with its own problems:1. Hard copy – not meaningful; loss of digital aspects; human vs. machine tolerance of error2. Standards – suffer from ‘value-added’ aspect of commercial profit needs; vendor implementation deviates from strict adherence; Ex: ASCIIUNICODE (8 bit to 16 bit)3. Museums – Can PCs run forever? Media durability (and  ongoing physical connectability) issues; best role is as future digi-archeologists (my term); cost is still an issue here4. Migration - (on-going translation as systems mature) results in orphaned items; error-prone; continuing expense; auto conversion is rare; authenticity problematic; not scalable–No combination of these solves the problem, either–Inadequacies remain22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 8Criteria for an Ideal Solution•Ideal = long-term; extensible; uniformly applicable; automate-able; doc-type-independent; facilitate management, functionality, & accessibility;•Assumptions: future computers will be faster & cheaper; able to perform all current operations or an equivalent;•Key Factors: Manageable cost, quality, quantity and safety22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 9Emulation Solution: “Annotate, Encapsulate, Transliterate, and Emulate”•Recreate original via software and/or hardware emulation•Requires encapsulation techniques (hardware, software, document, features) – note that HW has explicit specs but SW usually does not•Explanatory items are an integral part of the final archived document (metadata, user guide, etc.)•Does not address IPR, proprietary issues•Emulate hardware, document, OS or associated software? – single vs. multiple docs, multiple levels of docs; OS is as complicated to emulated as the software…“The only adequate specification of the behavior of a digital document is the one implicit in its interaction with its software. The only way to recreate the behavior of a digital document is to run its original software.” (p. 28)22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 10Emulation: Diagram22 Jan 2004/Joan Smith CS 791/891 Digital Preservation 11Emulation in a NutshellDiagram from: Holdsworth & Wheatley in Diginews Aug 200122 Jan 2004/Joan Smith CS 791/891 Digital Preservation 12Research Required for the Emulation Approach•Development of generic emulation techniques–VMware, Lindows, Universal Virtual Machine, Wintel, etc.–Lots of progress in emulation field•Maintaining understandable documents–“Bits in a bit stream can represent anything….” (Rothenberg)–There is both a human dimension and a digital dimension to ‘understanding’•Development of encapsulation techniques & associated metadata22