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NGDA Architecture Update

NGDA Architecture Update. Greg Janée. Three motivations. Archival has to be cheap & easy little incentive no funding Need to archive data semantics key differentiator from text, audio, video Focus on long-term preservation need to migrate whole systems. system. handle resolver.

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NGDA Architecture Update

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  1. NGDA Architecture Update Greg Janée

  2. Three motivations • Archival has to be cheap & easy • little incentive • no funding • Need to archive data semantics • key differentiator from text, audio, video • Focus on long-term preservation • need to migrate whole systems Greg Janée • May 16, 2005

  3. system handle resolver handle resolver storage database database database database fragile Typical repository architecture Greg Janée • May 16, 2005

  4. NGDA architecture access ingest Web ADL OAI bulk loader archival system storage subsystem standard, public data model databases, caches, etc. Greg Janée • May 16, 2005

  5. Post-NGDA architecture Web storage subsystem standard, public data model Greg Janée • May 16, 2005

  6. Storage system requirements • Req’s: • associate UUIDs/RIDs with bitstreams • retrieve global/local bitstream by UUID/RID • determine (parent) UUID of any bitstream • list all UUIDs • Satisfied by: • any filesystem • tag URIs for UUIDs • tag:library.ucsb.edu,2005:identifier Greg Janée • May 16, 2005

  7. directory UUID RID component Archival objects UUID Greg Janée • May 16, 2005

  8. Archival objects • Directory info per component • named relationship/position • format & semantics • by UUID references to definitions • fixity: checksum • provenance: isDerivative • policy: mutability • rights • Components may be provided by archive itself Greg Janée • May 16, 2005

  9. Example USGS Object x DOQQ derived metadata data x.fgdc x.tiff x.gif subtypeOf FGDC GeoTIFF TIFF Greg Janée • May 16, 2005

  10. Archives • Archive = set of archival objects • no structure • no free-floating bitstreams • In anticipation of federation: • associations may cross archive boundaries • archival objects may not Greg Janée • May 16, 2005

  11. Object types • Content • Format definition • Semantic definition • Provider • Organizational structures • collection • series • ingest session Greg Janée • May 16, 2005

  12. Archive-provider agreement • Defines • common structure of objects to be ingested • necessary validations • associations to other objects • policies, rights, etc. • Represents choke point • requires human evaluation Greg Janée • May 16, 2005

  13. Deferred functionality • Incremental ingest • Object revisions • Rights • 3rd-party access • Federation Greg Janée • May 16, 2005

  14. Status • Starting development now • Approach: iterative refinement Greg Janée • May 16, 2005

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