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PREMIS OWL. Sam Coppens Multimedia Lab Department of Electronics and Information Systems Faculty of Engineering Ghent University. Survey. Quick intro in semantic web Why PREMIS OWL? Design Example Conclusion. Intro Semantic Web. XML / XSD. Metadata in XML - PowerPoint PPT Presentation
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ELIS – Multimedia Lab
PREMIS OWL
Sam CoppensMultimedia Lab
Department of Electronics and Information SystemsFaculty of Engineering
Ghent University
2
ELIS – Multimedia Lab
Survey
• Quick intro in semantic web
• Why PREMIS OWL?
• Design
• Example
• Conclusion
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
INTRO SEMANTIC WEB
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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>
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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>
??
?
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
XML / XSD
??
?
? Structure
? meaning Tags
XML Schema
! Exchange FormatSam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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, …
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
RDFS
• RDF Schema• Standardised terms to describe concepts• Introduces classes and instances
• Subclasses, subproperties– Hierarchy!
Note1
TimhasAuthor
ClassNote
ClassPerso
n
rdf:type rdf:type
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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>
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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”
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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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ELIS – Multimedia Lab
WHY PREMIS OWL?
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
Why PREMIS OWL?
• Changing Technologies
World Wide Web Semantic Web
XML RDF, RDFS and OWL
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
Semantic Web
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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)
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
DESIGN
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
Design
• Design decisions:
– Stick as close as possible to the PREMIS 2.0 Data Dictionary.
– No information loss when migrating PREMIS XML PREMIS OWL
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
Design
• Changes:
– Every XML wrapper has become a class.– Object has 3 subclasses: File, Bitstream,
Representation.– Relations between the entities.– Linking to SKOS vocabularies.
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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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ELIS – Multimedia Lab
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
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
Design
• Linking to SKOS vocabularies:
• event types vocabulary (eventType)• preservation level role vocabulary
(preservationLevelRole)• message digest algorithm vocabulary
(messageDigestAlgorithm)
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
EXAMPLE
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
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ELIS – Multimedia Lab
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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ELIS – Multimedia Lab
Example
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Mets
Tiff Image 2Tiff image 1
JPEG image 1
JPEG Image 2
ValidationValidation
Ingestion Ingestion
Migration Migration
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Conclusion
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
• 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