PREMIS OWL
description
Transcript of PREMIS OWL
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
3
ELIS – Multimedia Lab
INTRO SEMANTIC WEB
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
4
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
5
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
6
ELIS – Multimedia Lab
XML / XSD
??
?
? Structure
? meaning Tags
XML Schema
! Exchange FormatSam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
7
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
8
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
9
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
10
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
11
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
12
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
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
13
ELIS – Multimedia Lab
WHY PREMIS OWL?
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
14
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
15
ELIS – Multimedia Lab
Semantic Web
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
16
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
17
ELIS – Multimedia Lab
DESIGN
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
18
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
19
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
20
ELIS – Multimedia Lab
Design
• Object has 3 subclasses: File, Bitstream, Representation
Subclasses based on the objectCategory property (“Bitstream”, “File”, “Representation”)
Object
Bitstream FileRepresentatio
n
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
21
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
22
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
23
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
24
ELIS – Multimedia Lab
EXAMPLE
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
25
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
Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
26
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
27
ELIS – Multimedia Lab
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