ELIS – Multimedia Lab PREMIS OWL Sam Coppens Multimedia Lab Department of Electronics and Information Systems Faculty of Engineering Ghent University

ELIS – Multimedia Lab

PREMIS OWL

Sam CoppensMultimedia Lab

Department of Electronics and Information SystemsFaculty of Engineering

Ghent University

2


Survey

• Quick intro in semantic web

• Why PREMIS OWL?

• Design

• Example

• Conclusion

Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL

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INTRO SEMANTIC WEB


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XML / XSD

Metadata in XML

<author> <uri>page</uri> <name>Ora</

name> </author>

<document>

<details>

<uri>href="page"</uri>

<author>

<name>Ora</name>

</author>

</details>

</document>

<document href="page">

<author>Ora</author>

</document>


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XML / XSD

XML problem:

<x> <y>page</y> <z>Ora</z>

</x>

<x>

<y>

<z>href="page"</z>

<v>

<w>Ora</w>

</v>

</y>

</x>

<x href="page">

<y>Ora</y>

</x>

??

?


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XML / XSD

??

?

? Structure

? meaning Tags

XML Schema

! Exchange FormatSam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL

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Semantic Web technologies

• Technologies developed by the World Wide Web Consortium (W3C)

• Goal: make the Web a universal medium for data, information and knowledge exchange

• HTML, XML -> RDF, RDFS, OWL, …


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RDF

• RDF (Resource Description Framework)• Triples: subject – predicate – object• URI to identify resources• “The author of the note is Tim”

• Serialisatie in XML:• <rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns#>

<Note rdf:about=http://www.example.org/#note> <hasAuthor rdf:resource="http://www.example.org/#Tim”/> </Note> </rdf:RDF>

Note TimhasAuthor


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RDFS

• RDF Schema• Standardised terms to describe concepts• Introduces classes and instances

• Subclasses, subproperties– Hierarchy!

Note1

TimhasAuthor

ClassNote

ClassPerso

n

rdf:type rdf:type


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OWL

• Web Ontology Language, W3C recommendation (2004)• Richer vocabulary• Defines advanced relations

– Data-typing– Cardinality– Rich typing van properties– …

• Example:

• Reasoning! complex ontologies

Note1

TimhasAuthor

ClassNote

ClassPerso

n

type type

isAuthorFrom

<owl:ObjectProperty rdf:ID=“isAuthorFrom”> <owl:inverseOf rdf:resource=“#hasAuthor”></owl:ObjectProperty>


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Ontology (described in OWL)

subClassOf

Birth date

DatatypeProperty

Class: Person

Class: Scientist

IndividualBirth date

“14/10/1801”

OWL-constructions• Class• DatatypeProperty• subClassOf• Individual• …

“Joseph Plateau”


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Semantisch Web

• SPARQL Protocol And RDF Query Language (SPARQL)– SQL like language for RDF– Example: search all texts of Tim

• SELECT ?x WHERE ?x hasAuthor Tim


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WHY PREMIS OWL?


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Why PREMIS OWL?

• Changing Technologies

World Wide Web Semantic Web

XML RDF, RDFS and OWL


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Semantic Web


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Why PREMIS OWL?

• Data model of PREMIS:

Dynamically relating theFive entities to each other.

XML: identifiers are used for modelling the relations.directed and not bidirectional!

OWL: resources are identified by a URIdirect relations between the entitities (bidirectional by using inverse relations)


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DESIGN


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Design

• Design decisions:

– Stick as close as possible to the PREMIS 2.0 Data Dictionary.

– No information loss when migrating PREMIS XML PREMIS OWL


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Design

• Changes:

– Every XML wrapper has become a class.– Object has 3 subclasses: File, Bitstream,

Representation.– Relations between the entities.– Linking to SKOS vocabularies.


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Design

• Object has 3 subclasses: File, Bitstream, Representation

Subclasses based on the objectCategory property (“Bitstream”, “File”, “Representation”)

Object

Bitstream FileRepresentatio

n


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Design

• Relations between the entities:– Every entity has become a class.

Every entity has a URI. No need for using the entities’ identifiers for

relating them.This URI is used for relating the different entities.

object properties and their inverse properties

Object

Identifiers

Event


22


Design

• Relations between the entities:– Every entity has become a class.

Every entity has a URI. No need for using the entities’ identifiers for

relating them.This URI is used for relating the different entities.

object properties and their inverse properties

Object

Identifiers

Event


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Design

• Linking to SKOS vocabularies:

• event types vocabulary (eventType)• preservation level role vocabulary

(preservationLevelRole)• message digest algorithm vocabulary

(messageDigestAlgorithm)


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EXAMPLE


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Example

Based on the louis example: http://www.loc.gov/standards/premis/louis-2-0.xml

PREMIS OWL example (serialised in N3 notation): https://docs.google.com/leaf?id=0BxtLo-HRghbvZWFjZmMwN2MtNTMyZS00NzY3LThmNzktMzMwYmFhZGM1N2Yx&sort=name&layout=list&num=50


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Example


Mets

Tiff Image 2Tiff image 1

JPEG image 1

JPEG Image 2

ValidationValidation

Ingestion Ingestion

Migration Migration

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Conclusion


• Ternary relations remain problematic in OWL identifiers

• Publication of the provenance information is not the primary concern of PREMIS OWL.

PREMIS = provenance metadata + technical metadata + rights metadata

Provenance metadata will become more important in the future. There are provenance models much more suited for interoperability and publication on het Web.W3C Provenance Incubator Group

• PREMIS OWL: http://mulitmedialab.elis.ugent.be/users/samcoppe/ontologies/Premis/premis.owl

Documents

ELIS – Multimedia Lab PREMIS OWL Sam Coppens Multimedia Lab Department of Electronics and Information Systems Faculty of Engineering Ghent University