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

2 ELIS – Multimedia Lab Survey Quick intro in semantic web Why PREMIS OWL? Design Example Conclusion Sam PREMIS Implementation Fair: PREMIS OWL

3 ELIS – Multimedia Lab INTRO SEMANTIC WEB Sam PREMIS Implementation Fair: PREMIS OWL

4 ELIS – Multimedia Lab XML / XSD Metadata in XML page Ora href="page" Ora Ora Sam PREMIS Implementation Fair: PREMIS OWL

5 ELIS – Multimedia Lab XML / XSD XML problem: page Ora href="page" Ora Ora ? ? ? Sam PREMIS Implementation Fair: PREMIS OWL

6 ELIS – Multimedia Lab XML / XSD ? ? ? ? Structure ? meaning Tags XML Schema ! Exchange Format Sam 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 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: Note Tim hasAuthor Sam 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 Tim hasAuthor Class Note Class Person rdf:type Sam 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 Tim hasAuthor Class Note Class Person type isAuthorFrom Sam PREMIS Implementation Fair: PREMIS OWL

11 ELIS – Multimedia Lab Ontology (described in OWL) subClassOf Birth date DatatypeProperty Class: Person Class: Scientist Individual Birth date “14/10/1801” OWL-constructions Class DatatypeProperty subClassOf Individual … “Joseph Plateau” Sam 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 PREMIS Implementation Fair: PREMIS OWL

13 ELIS – Multimedia Lab WHY PREMIS OWL? Sam 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 PREMIS Implementation Fair: PREMIS OWL

15 ELIS – Multimedia Lab Semantic Web Sam PREMIS Implementation Fair: PREMIS OWL

16 ELIS – Multimedia Lab Why PREMIS OWL? Data model of PREMIS: Dynamically relating the Five entities to each other. XML: identifiers are used for modelling the relations.  directed and not bidirectional! OWL: resources are identified by a URI  direct relations between the entitities (bidirectional by using inverse relations) Sam PREMIS Implementation Fair: PREMIS OWL

17 ELIS – Multimedia Lab DESIGN Sam 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 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 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 BitstreamFileRepresentation Sam 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 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 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 PREMIS Implementation Fair: PREMIS OWL

24 ELIS – Multimedia Lab EXAMPLE Sam PREMIS Implementation Fair: PREMIS OWL

25 ELIS – Multimedia Lab Example Based on the louis example: PREMIS OWL example (serialised in N3 notation): HRghbvZWFjZmMwN2MtNTMyZS00NzY3LThmNzktMzMwY mFhZGM1N2Yx&sort=name&layout=list&num=50 Sam PREMIS Implementation Fair: PREMIS OWL

26 ELIS – Multimedia Lab Example Sam PREMIS Implementation Fair: PREMIS OWL Mets Tiff Image 2Tiff image 1 JPEG image 1JPEG Image 2 Validation Ingestion Migration

27 ELIS – Multimedia Lab Conclusion Sam 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:  emis.owl