1. Conceptual Data Modelling for Digital Preservation Planets and PREMIS Angela Dappert

2. PREMIS – Preservation Metadata: Implementation Strategies A de-facto standard, but still developing The PREMIS Data Dictionary defines preservation metadata  … that supports long-term digital preservation  … that most preservation repositories need to know  … that is implementable  … that is technically neutral

3. The PREMIS Data Model  Data model  Relationships between entities  Semantic Units (“properties”)

4. Planets Data Dictionary  A data model  A specific vocabulary to describe concepts used across digital preservation processes  Use to model organizations’ preservation policies  Capture institutional preservation requirements  Reuse and share requirements and vocabulary  Informed digital object property ontology  Develop machine-interpretable models (as added value)

5. Methodology  Top-down approach: Create a model  from first principles  from literature analysis  Bottom-up approaches (validate and simplify):  Document analysis  Interview decision makers  Planets work-packages  extract concepts, vocabulary  compile a requirements base for re-use  categories of requirements

6. Planets Conceptual Model Risk specifying Preservation guiding Significant Characteristics

7. Planets and PREMIS Models - Different scope PREMIS Planets

8. Planets and PREMIS Models  PREMIS: Preservation Risks and Requirements outside the scope – non-dynamic  Planets: Events, Agents and Rights are re-used from PREMIS PREMIS Planets

9. Preservation Actions  Planets: Preservation Actions are a special case of PREMIS:Event that is richly modelled PREMIS Planets

10. Objects  Representations, Files / Bitstreams  PREMIS Bitstream : restricted to one file.  Planets Bitstream : sets of Bitstreams which can span several files  Components as subclasses of objects  PREMIS: file  Planets: logical file and physical file  logical file: expected checksum  physical file: actual checksum

11. Objects  PREMIS: Intellectual Entities currently not fleshed out  Planets: Intellectual Entities a subclass of Preservation Objects. PREMIS Planets

12. Environment  PREMIS: Environments subordinate to objects  Planets: Environments parallel concept to objects  Identify and describe environments  Model data carrier refresh, emulation as easily as migration PREMIS Planets

13. Properties  PREMIS: specific properties that statically describe digital objects for preservation repositories  Planets: rich, general property concept that dynamically describes the preservation environment for preservation processing PREMIS Planets

14. Properties Planets:  meta-level on which to describe the properties of Properties value origins data constraints units etc.  relationships to other Properties e.g. imageAspectRatio = imageWidth / imageHeight  Property ontology  Resolve property clashes between preservation services and file formats

15. Properties  Planets: Supports dynamic preservation processes Use to represent characteristics and requirements Metadata Storage Service Properties Property and Vocabulary Description Controlled Vocabulary

16. Properties  Planets: Supports dynamic preservation processes

17. Significant Characteristics  PREMIS: Value equivalence of a property  Planets: Rich requirement / business rule with tolerance or importance factors, context under which it applies  PREMIS: applies to and subordinate to one object  Planets: expresses constraints on Environments or combinations of Environments and Preservation Objects. Primary entity PREMIS Planets

18. Planets and PREMIS Interoperability  Next generation PREMIS is being informed by Planets.  Priscilla Caplan ( The Florida Center for Library Automation ) and Angela Dappert ( The British Library ) have been asked by the PREMIS Editorial Committee to consider how the PREMIS model can benefit from concepts developed in Planets.  They analyzed and documented the relationships between the Planets and PREMIS data dictionary.  The PREMIS Editorial Committee is currently considering changes.

19. Planets and PREMIS Interoperability  PREMIS improves its understanding of its own scope.  Different scope makes complete alignment unnecessary.  Planets PP2 data dictionary more granular than PREMIS  Implementation flexibility and extensibility of PREMIS facilitates embedding Planets features.

20. Contributions of the Planets Model  Comprehensive model – everything you need to capture fits into the model.  Risks, requirements, and actions are first class objects within the model.  Different requirements categories play different roles in preservation planning  The model lines up actions against the risks they mitigate.

21. Comprehensive model Everything you need to capture fits into the model  full range of preservation processes  technical as well as organizational properties  full range of preservation actions  full range of entities  full range of organizational types

22. Thank you