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