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Summary of Presentations of DELOS Summer School 2005

Summary of Presentations of DELOS Summer School 2005. 'Unpacking The OAIS Model' by David Giaretta 'Categories, Uses and Challenges of Metadata and Process Documentation' by Michael Day 'Workflow and Workflow Modelling' by Stephan Heuscher

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Summary of Presentations of DELOS Summer School 2005

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  1. Summary of Presentations of DELOS Summer School 2005 'Unpacking The OAIS Model' by David Giaretta 'Categories, Uses and Challenges of Metadata and Process Documentation' by Michael Day 'Workflow and Workflow Modelling' by Stephan Heuscher 'Role of Registries and Representation Information' by David Giaretta Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  2. OAIS - Denotation • Open Archive Information System • where • open = model standard developed using a public process and are publicly available • information = knowledge that can be exchanged, independent of form (representation) • archival information system = men and machines responsible for the acquisition, preservation and dissemination of information Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  3. The OAIS Model - History • The Consultative Committee for Space Data developed several discipline-independend standards • basis for TC20 (aircraft and space vehicles) and SC13 (data and information transfer) • general problem: information leakage through time • decided that SC13 should become archival standard Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  4. The OAIS Model - Background I How to achieve such an archival standard? • development of framework for digital archive standards • development of 'Reference Model' • ensure participation (across disciplines, apart from space communities) • focus on digital formats (but keep traditional archiving in mind) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  5. General Definition: Archive • a structured collection of documents, certificates, files, records • orientation: • long term preservation • access for public • not focused on the needs of the users (in contrast to a library) • a library (institution) sometimes fulfills the functions of an archive Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  6. General Definition: Reference Model • a referece model is the basis for • the development of special models and the construction of special applications • the comparison between models which describe the same issues • a reference model represents the ideal abstract key concepts Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  7. General Definition: Framework • a framework defines the architecture of an application or a process • a framework defines the structures and the control flow • it functions as a model • it helps to understand the relationship among the entities of a system • an important goal of a framework is to create/use reusable patterns/modules Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  8. The OAIS Model - Background II How to develop a standard? • investigation of other standards • definition of archiving of data • break archiving into functional areas e.g. ingest, storage, access • define interface between functional areas • use formal specification tools like UML, (data classes) data flow diagrams (interfaces) etc. Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  9. General Definition: Ingest • the acquisition of digital objects for a repository • has to identify and record the appropriate semantic and syntactic properties of the object Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  10. General Definition: UML • Unified Modeling Language • a standardised language to describe and specify structures of systems • not only used in software engineering, but also to model business processes Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  11. The OAIS Model - Background IV How is the status of the standard? • widely accepted not only by digital libraries, archives but also commercial organisations • ISO 14721 and final CCSDS available Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  12. The OAIS Model -Environment How does the model view of the OAIS environment look like? • producers provide information to be preserved • managers set OAIS policy as one concept in a broader policy domain(????) • consumers find and acquire digital information Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  13. The OAIS Model -Responsibilities Which responsibilities does the OAIS have? • negotiate for appropriate information of producers • control information conscerning long term preservation • ensure that the information is independently understandable • follow documented policies and procedures • determine the addressee of the information • make the information available Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  14. The OAIS Model-Information Terminology • information represented by data • if the data object is interpreted with the help of representation information, the information object is accessible • an information package is a conceptual unit consisting of content information and preservation description information (PDI) • types of information: • rendered • non-rendered • others Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  15. The OAIS Model - Information Object (UML) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  16. The OAIS Model - Representation Information (UML) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  17. The OAIS Model - Information Types (UML) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  18. The OAIS Model - Content Information • (primary) object of preservation • needs to be negotiated between producer and OAIS • The data object in the content information can be • digital • physical Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  19. The OAIS Model - Descriptive Information • contain the data which allow access to a document • can be used by the consumer e.g. to analyse or retrieve information Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  20. The OAIS Model -Packaging Information • relates the components of the package into identifiable entity of media data • e.g. tape marks, file names Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  21. The OAIS Model -Archival Information Package Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  22. The OAIS Model - Preservation Description Information • Provenance Information • description of Content information source e.g. pointers to the original, pointers to earlier versions • Context Information • description of relations outside the Information Package e.g. pointers to documents from the original environment of the publication • Reference Information • unique identifier e.g. bibliographic identifier • Fixity Information • protection of alteration e.g. by checksum, digital signature Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  23. The OAIS Model - Types of Information Packages • Submission Information Packages (SIP)information submitted by producer (based on negotiations between producer and OAIS) • Archival Information Package (AIP)used for preservation • Dissemination Information Package (DIP)distribution of information of one or more AIPs to the consumer using the OAIS Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  24. The OAIS Model - Functional View I • Principles: • Stress on major functional areas important to digital archiving • Use of functional decomposition, but not too detailed • Identification of common services Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  25. The OAIS Model - Functional View II Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  26. The OAIS Model - Functional Entities • Ingest • accepts SIPs • prepares content for storage • Archival Storage • provides services and functions for storage • Data Management • provides services and functions maintaining descriptive information and internal archive administration data • Administration • manages the overall operation of the archive • Preservation Planning • monitors environment of the OAIS • provides recommendations • Access • allows the consumers to access the information content of the OAIS as a product Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  27. The OAIS Model - Digital Migration • Migration of digital information within the OAIS in order to preserve it • full information content • replacement of old information implemetation • motivated by: • media decay • cost effectiveness • new customer requirements Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  28. The OAIS Model - Types of Digital Migration • Refreshment • no bit changes • Replication • no change of packaging or content information bits • Repackaging • some bits change in packaging information • Transformation • reversible: bit changes can be reversed by an algorithm • irreversible Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  29. The OAIS Model - Problems of Access Presevation • cost effective use of APIs only possible if • not too complicated • applicable on many different AIUs (Archive Information Unit) • extensive testing necessary when porting API to a new environment • preservation through emulation of executables problematic Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  30. The OAIS Model - Archive Interoperability • need for interoperability among the different archives • consumers need common aids, common DIP, common package descriptor for access • producers need common SIP, one single repository • managers need cost reduction by sharing resources Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  31. The OAIS Model -Categories Archive Interoperability • independent: • no knowledge from one archive to another • cooperating • common submission and dissemination standards • no common access • federated • common access provided • shared resources • resources shared but not externally visible (e.g. shared storage) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  32. The OAIS Model-Possible Architecture Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  33. Metadata - Definitions • Data about data • Structured information to describe, explain, locate ... information objects • Definition by function • Descriptive metadata • Structural metadata • Administrative metadata • understandable by men and machines • many different standards Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  34. Preservation Metadata - Definitions • Types of data that allow the re-creation and interpretation of structure and content of digital data over time (Ludäsher, Marciano, Moore, 2001) • The information used by an repository to support the digital preservation process (PREMIS working group, 2005) • All digital preservation strategies depend on the creation of appropriate metadata • Preserving the right metadata is the key to preservation (Duff, Hofmann, Troemel, 2003) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  35. Preservation Metadata - Roles • reference to each digital object • provides structural, descriptive, administrative ... information • understanding the history of data (how it was cleaned, what parameters were used) • handling of huge amount of data (searchability) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  36. PREMIS WG - About • Preservation Metadata Implementation Strategies • sponsored by OCLC (Online Computer Library Center) and RLG (Research Libraries Group) • since 2003 • international WG • main objectives: • a basic set of preservation metadata ("Data Dictionary") • strategies for encoding, packaging, storing, exchanging metadata • output: • Implementation Survey Report (2004) • PREMIS Data Dictionary (2005) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  37. PREMIS WG - Observations • little experience of digital preservation: will metadata be adequate • the OAIS model was the basis for many repositories • METS was the most common scheme for non descriptive metadata • metadata is stored together with data objects (self-documenting) and in data bases Trends • keep originals to limit the risk • use of multiple preservation strategies Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  38. PREMIS WG - Data Dictionary • based on OAIS framework • a set of implementable semantic units • defines metadata that maintains iability, renderability, understandability, authenticity and identity in a preservation context • not focused on descriptive metadata • metadata set for the needs of repositories • automatic capture of metadata • the Data Dictionary implementation is independent (does not determine how s.th. is stored) • everything is based on a simple data model Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  39. PREMIS WG - Data Model Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  40. PREMIS WG - Data Model - Definitions I • Entities • Digital Object • Interlectual Entity (considered to be covered by existing standards) • Event • Agent • Rights • Relationships • statements of association between instances of entities • structural relationships • derivation relationships • dependency relationships • Semantic Units • properties of one entity • have values Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  41. PREMIS WG - Data Model - Definitions II • Digital Objects • discrete unit of information • files = named and ordered sequence of bytes known by an operating system • bitstreams = a set of bits embedded within a file • representation = the set of files needed for the rendering of an Interlectual Entity • Interlectual Entity • a coherent set of content that can be viewd as a single unit • Event • an action involving at least one object or agent of the repository • objects can be connected to several actions Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  42. PREMIS WG - Limits • no focus on descriptive metadata • no definition of the characteristics of an agent • no consideration of rights, which are not directly associated with preservation actions (e.g. access) • no definition of all technical metadata • no documentation of media or hardware • no consideration of the business rules of a repository Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  43. PREMIS WG - Metadata Capture • capture metadata which already exists • develop tools for automatic capture of metadata • create event metadata at different points of the object life cycle (creation, ingest, migration Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  44. PREMIS WG - Interoperability • important • to support reuse of existing metadata • to exchange digital objects • centralised repositories specialised on file format information and metadata schemas Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  45. Workflow - Definition • a specific representation of a process • represents activities, applications and participants (humans or machines) • represents the structure of tasks, who performs a task, the synchronisation of tasks • controlled by a workflow management system • can be graphically depict by workflow diagrams Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  46. Workflow - What for? • Traceability of processes, documentation of handling • quality control tool for automated processes • Knowledge sharing, important for • centralised implementation • iterative development Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  47. Workflow and Preservation • workflows mainly for arrangement purpose • implicit knowledge • local differences • no standards • very adaptive • only a small number of archives: no out of the box solutions Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  48. Workflow - Advantages/Disadvantages • Disadvantages • costs • complexity • more surveillance • too many tools and standards • Advantages • documentation • automation • more control • sharing knowledge • connecting applications Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  49. Workflow - Lifecycle • Planning • requirements analyses • defining goals • Implementation • design workflow on basis of requirement analyses • evaluate tools • Enactment • Evaluation • Planning... (based on evaluation results) Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

  50. Workflow - Routing • Routing: what to do next? • manifestation of control flow • definition of sequence • routing needs to be defined in dependeny of the outcome of an action Standards in Digital Preservation Summary of Delos Summer School 2005 see last pages for details on lecturers

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