The Flexible Extensible Digital Object Repository Architecture

1. The Flexible Extensible Digital Object Repository Architecture • A set of abstractions that can be used to represent different kinds of data • A repository management system • A foundation for many information management applications • Designed to make data “durable” over the long term

2. The Fedora Project • Developed at Cornell under an NSF grant • UVA Library re-interpreted the architecture and created the first practical implementation • 3 year project funded in 2001 by Andrew W. Mellon Foundation to create open-source system • Another 3 years of development funded by Mellon in 2004

3. Fedora Commons, Inc. • 501-(c)3 private, non-profit company • 4-year project funded by Moore Foundation to become self-sustaining • Continuing software development • Moving towards community-based software development • Establishing “solution communities” for the development of solution bundles.

4. Other Fedora Commons Projects • Akubra – storage plug-in module with tranactional file system • Mulgara – RDF indexing engine • Topaz – core semantic knowledgebase components

5. The world we work in… Data Curation, Linking, Publishing Scholarly and Scientific Collections Preservation and Archiving Education, Knowledge Spaces blog and wiki and more …

6. 148 Current Known Users • Broadcasting and media – 1 • Consortia – 6 • Corporations – 13 • Government agencies – 4 • IT- Related Institutions – 9 • Medical Centers and Libraries – 4 • Museums and Cultural Organizations – 4 • National Libraries and Archives – 16 • Professional Societies – 2 • Publishing - 4 • Research Groups and Projects – 14 • Semantic and Virtual Library Projects - 6 • University Libraries and Archives - 65

7. 7 Known Vendors and Integrators: • Acuity Unlimited • Aptivate • Atos Origin, France • Fitz Karlsrhue • MediaShelf, LLC • Sun Microsystems • VTLS

9. Solution Communities • Community group that creates and maintains the vision for solution bundle in an area • Gathers resources to create software for solution • Coordinates development with the FC Architecture Council • Smaller group that gets things done will emerge

10. Solution Areas • Data Curation – Sayeed Choudry, from Johns Hopkins University • Preservation and Archiving – Ron Jantz, from Rutgers • Open Access Publishing – Rich Cave, from PLOS • Integration Services – Matt Zumwalt from MediaShelf, LLC

11. Other Possible Community Groups • Other software development groups • News and Publications Outreach group that works with our Communications Director • Issue/advocacy groups that work on standards important to the community

12. Making complex digital information “durable” is a very hard problem • The existence and meaning of content needs to be verifiable as technologies change • A history of the changes to the encoding and state of content must be reliably provided • A meaningful context for any unit of content may be one of many and must be sustained • Complex resources will increasingly be dispersed across institutional boundaries.

13. The Fedora abstractions provide a durability framework. • Content is “unitized” as information objects that combine data, metadata, policies, relationships and the history of the object. • Complex digital resources are formally defined graphs of related objects. • The public view of the content is presented as abstract behaviors. • The web services orientation of Fedora provides the basis for repository federation.

14. A data object is one unit of content, represented by an XML file.

15. Datastreams hold or represent the content • Inline XML : content in the FoXML object • Managed Content : content is managed by the repository • Externally Referenced: URL of remote content is in the FoXML object • Re-directed Referenced: external but content is not disseminated through Fedora

16. Datastream Characteristics • Can have any number and multiple types in the same object • Versioned automatically by default • Checksums automatically by default • Formal identifier • Alternate identifiers • Audit trail maintained about all datastream actions

17. Relationships Among Objects • Describes adjacency relationships among objects • RDF data of the form: PID – typeOfRelationship – relatedObjectPID • Can used to assemble aggregations of objects • Can build graphs of relationships to feed into user interfaces

18. Objects Representing Aggregations • Creating parent objects for complex resources • Representing explicit collections • Representing implicit collections • Creating digital surrogates for physical entities

19. Optional Object Behaviors • Data objects can have different views or transformations • Sets of abstract behaviors that different kinds of objects can subscribe to • Corresponding sets of services that specific objects can execute • The business logic is hidden behind an abstraction

21. Content Models • Create classes of data objects • Expressed as Cmodel objects • A Cmodel object defines the number and types of data streams for objects of that class • A Cmodel object binds to service objects to enable appropriate behaviors to be inherited by data objects

22. Persistent ID (PID) Persistent ID (PID) Metadata System System Metadata Datastreams Datastreams Service Definition Metadata Persistent ID (PID) System Metadata Persistent ID (PID) Datastreams RDF data Service Binding Metadata (WSDL) System Metadata Datastreams Service Definition Object service subscription Cmodel Object service contract data contract Data Objects Web Service Service Mechanism Object

23. A behavior call has the form: Object PID + SDef Name + Method Name • Other components include: • Parameter values used by the method • Datetime stamp for earlier version

24. The Fedora Service Framework GSearch OAI Simple JMS Fedora Repository Service DirIngest Preserve These are the core servivce components we distribute.

25. http://www.fedora-commons.org/

26. Examples • Text, images only • Art and Architecture • Quantitative data • Aggregation objects