Flexible and Extensible Digital Object and Repository Architecture (FEDORA)

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Flexible and Extensible Digital Object and
Repository Architecture (FEDORA)
Sandra Payette Cornell University payette_at_cs.corne
ll.edu
CS 502 Computing Methods for Digital
Libraries April 20, 2000
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Component-Ware Digital Libraries
User Gateway Service
Name Service
Collection Services
Index Services
Digital Objects
Repository Services
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FEDORA Goals

• Distribution - of digital content and services
• Interface Stability - for digital objects
• Interoperability - for digital objects and
  repositories
• Extensibility - naturally evolving type system
• Flexibility - community-driven type development
• Security - rights management and access control
• Preservation - longevity of digital objects

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FEDORA

• Digital Object
• container for aggregating any digital material
• disseminations of complex types
• global extensibility mechanisms
• Repository
• Service layer for contained DigitalObjects
• Object lifecycle management
• Secure environment for running mobile code

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FEDORA History

• Digital Object vision (Kahn/Wilensky)
• Warwick Framework (container model)
• Distributed Active Relationships (Lagoze)
• Cornell FEDORA (Payette, Lagoze)
• CNRI Repository (Arms, Blanchi, Overly)
• CNRI/FEDORA Interoperability Project
• UVA/FEDORA (Staples, Weyland) - Complex
  disseminators, XML/XSL, web integration
• Project Prism (DLI2) Security, preservation
• Lecture Browser (Mukhopadhyay, Newman)

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Fedora DigitalObjects can be...

• Simple, familiar entities

• Complex, compound, dynamic objects

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FEDORA DigitalObject Model
MIME-typed stream of bytes
Book
Service Request upon external source
Internal DataStream
Reference DataStream
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Digital Object is...
getSection getArticle
getTrack getLabel
getChapter getPage
getFrame getLength
recognizable by what it can do
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Disseminator Type

• A set of behaviors that formally describes the
  functionality of any global or community-specific
  notion of content.

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Disseminator

• A generic component that associates
• a set of behaviors with a DigitalObject.

Extensible Type Disseminator
Generic behaviors
Extended behaviors
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FEDORA DigitalObject
Extensible Behavior Layer
Primitive Disseminator
Structural Kernel
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Client communicates with generic requests
GetChapter GetTOC GetPage
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DigitalObject Interface Stability
Disseminator Type
Interface
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DigitalObject Extensibility Adding New Types
Book
The same underlying data...
Mechanism
Structure
Interface
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A Disseminator is a Generic Component...
that references another FEDORA
DigitalObject that disseminates a servlet
DataStreams DS1 TypeID URNDC1
GetDCField GetDCRecord
DC
application/ MARC
DS1
GetMethods(DC)
application/ postscript
DS2
GetDCField(e), GetDCRecord
to produce non-generic behaviors
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Extensibility a look under the hood
CTID URNDC1
DC
application/ MARC
application/ postscript
Digital Object attains its extended behaviors
through association and delegation
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Registration and Proliferation of Disseminator
Types

• Disseminator Types registered in the Handle
  System
• visible when URN of a Signature is registered
• usable when URN of a Servlet is registered
• Other DigitalObjects can use Disseminator Types
  by referencing these URNs.

Fedora Repository
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Big Picture Cooperation among non-cooperating
sources
Learning Object
Video Archive
Library Catalog
Museum Image Database
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Big Picture Interoperable Repositories
RAP Client
Name Service
Repository
Repository
Repository
Repository
Cornell Library Collections
NCSTRL
Cornell CS Lectures
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Current Status

• FEDORA Implementation
• CORBA IDL defines all component interfaces
• Java/CORBA reference implementation (Fedora
  server and GUI client).
• Experimental Disseminator Types
• Dublin Core
• Image
• Article/Technical Report
• Book (with CNRI / Library of Congress)
• Lecture Object (video, slides)

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Current Work Security

• Access Control for Digital Objects
• Monitor all operations, generic and extended
• Security Automata (Schneider)
• Policy-carrying, policy-enforcing Digital Objects
  using
• PoET (Erlingsson and Schneider)
• Fedora (Payette, Lagoze, Dushay)

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AccessManager
Disseminator protected by an AccessManager. The
DC Servlet is a piece of mobile code that is
dynamically in-lined with the policy for the
object.
URN1
URNDC1
GetDCField GetDCRecord
DC
MARC
policy
Remote Servlet Utilized
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Future Work Preservation Augmented
DigitalObjects
Sets of methods we will define
Preserve
Book
P
preservation metadata
DS1
application/ postscript
DS2
Preservation Service
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Future Preservation Policy Enforcement
Preservation Surrogate Object
Monitors DigitalObject state and catches
unacceptable, or risky transitions
policy
Preservation Service
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References

• FEDORA Home Page, http//www.cs.cornell.edu/cdlrg
  /fedora.html
• Payette, Blanchi, Lagoze, and Overly
  Interoperability for Digital Objects and
  Repositories The Cornell/CNRI Experiments,
  D-Lib Magazine, May 1999, http//www.dlib.org/dlib
  /may99/payette/05payette.html
• Payette and Lagoze Flexible and Extensible
  Digital Object and Repository Architecture
  (FEDORA), ECDL 1998, http//www.cs.cornell.edu/pay
  ette/papers/ECDL98/FEDORA.html
• Lagoze and Payette An Infrastructure for
  Open-Architecture Digital Libraries, Technical
  Report, 1998 http//ncstrl.cs.cornell.edu/Dienst/U
  I/1.0/Display/ncstrl.cornell/TR98-1690
• Daniel, Lagoze, and Payette, A Metadata
  Architecture for Digital Libraries, IEEE ADL
  1998, http//www.cs.cornell.edu/lagoze/papers/ADL9
  8/dar-adl.html

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References cont.

• Schneider, Fred B., Enforceable Security
  Policies, Technical Report, Department of
  Computer Science, Cornell University, July
  1999,http//cs-tr.cs.cornell.edu80/Dienst/UI/1.0
  /Display/ncstrl.cornell/TR99-1759
• Erlingsson, Ulfar and Fred Schneider, SASI
  Enforcement of Security Policies A
  Retrospective, Technical Report , Department of
  Computer Science, Cornell University, July 1999,
  http//cs-tr.cs.cornell.edu80/Dienst/UI/1.0/Disp
  lay/ncstrl.cornell/TR99-1758
• Erlingsson, Ulfar and Fred Schneider, IRM
  Enforcement of Java Stack Inspection, Technical
  Report , Department of Computer Science, Cornell
  University, February 2000,http//cs-tr.cs.cornell
  .edu80/Dienst/UI/1.0/Display/ncstrl.cornell/TR200
  0-1786