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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.

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The flexible extensible digital object repository architecture
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

The fedora project
The Fedora Project Architecture

  • 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

Fedora commons inc
Fedora Commons, Inc. Architecture

  • 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.

Other fedora commons projects
Other Fedora Commons Projects Architecture

  • Akubra – storage plug-in module with tranactional file system

  • Mulgara – RDF indexing engine

  • Topaz – core semantic knowledgebase components

The world we work in
The world we work in… Architecture

Data Curation, Linking, Publishing

Scholarly and Scientific Collections

Preservation and Archiving

Education, Knowledge Spaces

blog and wiki

and more …

148 current known users
148 Current Known Users Architecture

  • 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 known vendors and integrators
7 Known Vendors and Integrators: Architecture

  • Acuity Unlimited

  • Aptivate

  • Atos Origin, France

  • Fitz Karlsrhue

  • MediaShelf, LLC

  • Sun Microsystems

  • VTLS

Solution communities
Solution Communities Architecture

  • 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

Solution areas
Solution Areas Architecture

  • 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

Other possible community groups
Other Possible Community Groups Architecture

  • 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

Making complex digital information durable is a very hard problem
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.

The fedora abstractions provide a durability framework
The Fedora abstractions provide a durability framework. hard problem

  • 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.

Datastreams hold or represent the content
Datastreams hold or represent file.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

Datastream characteristics
Datastream Characteristics file.

  • 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

Relationships among objects
Relationships Among Objects file.

  • 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

Objects representing aggregations
Objects Representing Aggregations file.

  • Creating parent objects for complex resources

  • Representing explicit collections

  • Representing implicit collections

  • Creating digital surrogates for physical entities

Optional object behaviors
Optional Object Behaviors file.

  • 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

Content models
Content Models file.

  • 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

The flexible extensible digital object repository architecture

Persistent ID (PID) file.

Persistent ID (PID)







Service Definition


Persistent ID (PID)



Persistent ID (PID)


RDF data

Service Binding

Metadata (WSDL)

System Metadata


Service Definition Object



Cmodel Object

service contract

data contract

Data Objects



Service Mechanism Object

The flexible extensible digital object repository architecture

A behavior call has the form file.:

Object PID + SDef Name + Method Name

  • Other components include:

  • Parameter values used by the method

  • Datetime stamp for earlier version

The flexible extensible digital object repository architecture

The Fedora Service Framework file.





Fedora Repository Service



These are the core servivce components we distribute.

Examples file.

  • Text, images only

  • Art and Architecture

  • Quantitative data

  • Aggregation objects