1. Enhanced Content Models
JISC Developers Happiness Days
2. Fedora EU Usergroup meeting
London, 2009
Asger Blekinge-Rasmussen
Kåre Fiedler Christiansen

2. Program Introduction A look at Fedora Objects
Traditional Content Models
Enhanced Content Models
Description languages
Validator
Autogenerated user interfaces

3. Introduction Shift of paradigm Catalog cards ­> interlinked content
Heterogeneous collections in the same repository
A single metadata model will not do
Need for a Data Model Description Language
Extension of Fedora 3.x Content Models
Precise description of XML datastreams
Precise description of relations

4. A look at Fedora Objects
Interrelated objects
Datastreams in objects
Content Models

5. Traditional Content Models
Content Models declare the classes of data objects
Content Models declare the existince of datastreams in data objects
Content Models associate disseminators with data objects

6. Enhanced Content Models
Extra information in Content Models. Backwards compatible.
ECMs declare the allowed relations, with cardinality and target classes for data objects
ECMs declare the schema for all xml datastreams.
ECMs:
Describe only properties about subscribing objects
Describe all properties about subscribing objects

7. Description Languages
Datastreams
XML
XMLSchema
Relations
RDF
RDFSchema / OWL Lite

8. Description Languages - Datastreams
<dsCompositeModel>
<dsTypeModel ID="DC">
<form MIME="text/xml"/>
</dsTypeModel>
</dsCompositeModel>

9. Description Languages - Datastreams
<dsCompositeModel>
<dsTypeModel ID="DC">
<form MIME="text/xml"/>
</dsTypeModel>
</dsCompositeModel>

10. Description Languages - Datastreams
<dsCompositeModel>
<dsTypeModel ID="DC">
<form MIME="text/xml"/>
<extensions name="SCHEMA">
<schema:schema
type="xsd"
object="example:example_schema_object"
datastream="DC_SCHEMA"/>
</extensions>
</dsTypeModel>
</dsCompositeModel>

11. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
</owl:Class>
</rdf:RDF>

12. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
</owl:Class>
</rdf:RDF>

13. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
</owl:Class>
</rdf:RDF>

14. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
<rdfs:subClassOf>
<owl:Restriction>
<owl:onProperty rdf:resource="#isPartOfCollection"/>
<owl:minCardinality rdf:datatype="integer">1</owl:minCardinality>
</owl:Restriction>
</rdfs:subClassOf>
</owl:Class>
</rdf:RDF>

15. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
<rdfs:subClassOf>
<owl:Restriction>
<owl:onProperty rdf:resource="#isPartOfCollection"/>
<owl:minCardinality rdf:datatype="integer">1</owl:minCardinality>
</owl:Restriction>
</rdfs:subClassOf>
</owl:Class>
</rdf:RDF>

16. Description Languages – Relations (in “ONTOLOGY” datastream)
<rdf:RDF xml:base="
<owl:ObjectProperty rdf:about="#isPartOfCollection"/>
<owl:Class rdf:about="info:fedora/doms:ContentModel_DOMS">
<rdfs:subClassOf>
<owl:Restriction>
<owl:onProperty rdf:resource="#isPartOfCollection"/>
<owl:minCardinality rdf:datatype="integer">1</owl:minCardinality>
</owl:Restriction>
</rdfs:subClassOf>
<owl:allValuesFrom rdf:resource="info:fedora/doms:ContentModel_Collection"/>
</owl:Class>
</rdf:RDF>

17. Validator
A validator for dataobjects subscribing to enhanced content models
Built as a webservice
Built into Fedora via API hooks.
Added meaning to the object State
Objects in State Active cannot be changed
When objects change to State Active, they are validated. If validation fails, the change is forbidden.
Error reporting done via subclasses of ServerException

18. Autogenerated user interfaces
Precise description of contents allow for autogenerated programmatic interfaces
In effect, a GUI could wrap itself around the objects in the repository
Let me demonstrate our version :)

19. Rounding up Questions? Websites
Project homepagehttp://wiki.statsbiblioteket.dk/domswiki
Enhanced Content Models site on the Fedora wikihttp://tinyurl.com/bh3966
This work has been funded by
DEFF, Denmark's Electronic Research Library
State and University Library, Denmark