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Conceptual Data Modellingfor Digital PreservationPlanets and PREMIS
Angela Dappert
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
The PREMIS Data Model
Data model Relationships between entities Semantic Units (“properties”)
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)
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
Planets Conceptual Model
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
hasOutputEnvironment
hasRequirementsSet1..*
hasRequirementsSet /hasRequirement
1..*
hasInputEnvironment
hasRequirement
1
hasOutputPreservationObject
0..*
Contains
hasEnvironment1..*
hasCharacteristic
hasRisk
1
hasInputPreservationObject
0..*
0..*
hasCharacteristic
0..*
hasEnvironment
hasCharacteristic
hasRisk
hasParentEnvironment
• Risk specifying
• Preservation guiding
• Significant Characteristics
Planets and PREMIS Models - Different scope
PREMIS
Planets
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
Preservation Actions
Planets: Preservation Actions are a special case of PREMIS:Event that is richly modelled
PREMIS
Planets
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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
Objects
PREMIS: Intellectual Entities currently not fleshed out
Planets: Intellectual Entities a subclass of Preservation Objects.
PREMIS
Planets
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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
Properties
Planets: Supports dynamic preservation processes
Use to represent characteristics and
requirements
Metadata Storage Service
Properties
Property and VocabularyDescription
Controlled Vocabulary
Properties
Planets: Supports dynamic preservation processes
Use to represent characteristics and
requirements
Metadata Storage Service
Properties
Store
Requirements Evaluation
Matchcharacteristics
with requirements
Use to express
characteristics
Use to express require-ments
Object & Envrmt., Tool
Characteristics
Property and VocabularyDescription
Characterisation /Testbed
Business Modelling
Requirements
Take action:- Preservation Watch / Risk Assessment- Preservation Planning- Preservation Action
Evaluation of Output
Feedback
Controlled Vocabulary
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
Characteristic
PreservationRisk
PreservationAction
PreservationGuidingRequirementsSet
PreservationObject Environment
Requirement
Agent
RightEvent
1..*
1..*
0..*
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.
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.
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.
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
Thank you