FEDORA

1. FEDORA
Selecting and Implementing an Open Source Digital Repository
Corey Keith
ckeith@loc.gov

2. Introduction
 History
 FEDORA Overview
 Object Oriented Principals
 LC’s Requirements
 LC’s Architecture
 Review

3. Pop Quiz
 XML
 OAIS
 METS
 FEDORA
 DSPACE

4. FEDORA History
 Continuing Research Project
– Cornell 1997
 Prototype Application
– University Virginia
 Fedora 1.0
– Open Source Release 2002
 Fedora 1.2
– Tomorrow!

5. Options, options, options
 Very few tools directly compete with
each other
 Many tools can be used to accomplish
similar behavior
 Many tools fulfill parts of the
functionality needed for a repository
 Roll your own solution

6. Why Fedora?
 Repository Architects & Developers
Excited 
 Object oriented approach to digital
objects
 Open Source Project
– Funded development (and support)
 Java Based
– Multiple HW Platforms

7. Flexible
 Integrates well with existing systems
– CGI Scripts
– Web Services
 Leaves most decisions to implementers

8. Extensible
 Again, no product can do it all
– Imaging, Audio, Transformations,
Courseware
 Easy to add new functionality to objects
 Embraces web services
 Open API’s
– Access
– Management

9. Digital Object
 What is the definition of a digital object?
–Documents, such as
articles, preprints, working
papers, technical reports,
conference papers
–Books
–Theses
–Data sets
–Computer programs
–Visualizations,
simulations, and other
models
–Multimedia publications
–Administrative records
–Published books
–Bibliographic datasets
–Images
–Audio files
–Video files
–Reformatted digital library
collections
–Learning objects
–Web pages
list taken from the dspace.org website

10. Repository Architecture
 Objects
 Behavior Definitions
 Behavior Mechanisms
 API
– Management
– Access

11. Object Oriented
 A software design method that models the
characteristics of abstract or real objects
using classes and objects.
 Proven Techniques for Software
Development
– Requirements gathering – Use Cases
• Developers speak to librarians and other stakeholders
 Facilitates reuse of functionality
 Design Patterns
 Not hacking Perl Scripts to make an
institutional repository

12. Object Oriented
 Data
– Metadata
• MODS – Descriptive
• METS – Structural
• MIX, etc – Technical
– Bit streams
• Actual Files – JPG, TIF, WAV, MP3, TEI, EAD
 Methods (Behaviors)
– Do stuff with the data

13. Object Oriented Concepts
 Classes
– Objects of the same type belong to a class
 Interfaces
– A contract defining behaviors a class of objects
will implement
 Encapsulation
– Behaviors operate on the data in an object
 Reflection
– Discover what interfaces and behaviors an object
implements

14. Image Objects
 Two File Image Object
– Data
• Hi Resolution Version: tif
• Low Resolution Version: jpg
 MrSID File Image Object
– Data
• MrSID File

15. Basic Image Interface
 getHighResolutionTIF
 getLowResolutionJPG

16. Basic Image Interface
Implementations
 Two File Image Object
– getHighResolutionTIF
• returns high resolution TIF
– getLowResolutionJPG
• returns low resolution JPG
 MrSID Image Object
– getHighResolutionTIF
• processes the MrSID file to return a high resolution TIF
file of the image
– getLowResolutionJPG
• processes the MrSID file to return a low resolution JPG
of the image

17. Sheet Music Object
 Data
– MODS Metadata
– Images of the pages (Image Objects)
– TEI encoded text of the lyrics (TEI Objects)
 Behaviors
– getPageImage(Pagenumber)
• Invoke the getLowResolutionJPG to return the image!
– getMODS
– getLyrics

18. Persistent ID (PID)
Behavior Definition
Metadata
SystemMetadata
DatastreamsData Object
Persistent ID (PID)
Service Binding
Metadata (WSDL)
SystemMetadata
Datastreams
Persistent ID (PID)
Disseminators
Datastreams
System Metadata
Behavior Mechanism Object
Behavior Definition Object
FEDORA’s Interface Implementation
graphics taken from presentations available at www.fedora.info

19. What is FEDORA?
 “Plumbing”
 Manage associations between objects
and their interfaces
 Invoke behaviors from an interface
which an object subscribes
 Manages or references files

20. What FEDORA
currently does not do?
 “Digital Library in a Box”
– Requires integration and custom
development
 Prescribe the right way to do things
– Implementers are free to choose
– Best practices still being fleshed out

21. LC’s Requirements
 Complex Digital Objects
– Structurally
• METS structMap
– Rich descriptive metadata
• Exploiting MODS features
– relatedItem

22. Choosing Repository Software
 Fedora provides a foundation to build
on
 LC member of initial deployment team
 No other software is like FEDORA
– Except general purpose programming
languages

23. How LC is implementing
FEDORA
 Types of Digital Objects
– Sheet Music
– Scores
– Sound Recordings
– Compact Discs
– Manuscripts
– Photographs
– Websites
– “Collections”
 Less emphasis
– Intellectual output of university’s research faculty

24. METS Profiles
 Correlates well with classes of objects
 Articulates
– Structure of an object
– Metadata requirements
 METS documents conforming to
profiles are ingested into repository
– Atomization
– Behavior association

25. Architecture
 Fedora (Repository)
 Cocoon (Application Layer)
Fedora
Repository
System
web browser
cocoon
Fedora Service APIs
user

26. SIP vs AIP
 Complex digital objects are atomized into
small reusable objects upon ingest to
FEDORA
– Sheet Music METS Profile (SIP)
• Sheet music object (AIP)
– Structural metadata encoded in METS
– Descriptive encoded in MODS
• Image objects for each page (AIP)
– TIF and JPG Files
– Technical encoded in MIX
• TEI object for the lyrics (AIP)
– TEI File

27. Why this Architecture?
 Clean Separation of Concerns
– Logic: Makes it go!
– Content: From FEDORA
– Style: Web Designers
 Object not bound to display
– Repository is for preservation of metadata and
files not markup (HTML)
– Markup accomplished in cocoon layer
 Leverage use of METS structural metadata
 Performance: Cocoon Caching

28. User Interface Development
 Web Designers
– Relate to objects and behaviors
– Can develop in HTML for display
– XSLT
• Uses XML from repository to drive display

30. Other Pieces of the
Repository Puzzle
 Other open source tools
– Cocoon
• XML Publishing Framework
– Lucene
• Text Indexing and Search API
 Someone has to write software!
– Java to build Lucene indexes
– XSP searching
– More XSLT than you want to see

31. Digital Object Production
 How are we building these digital
objects?
– MySQL
– Cocoon
– XSLT
– Homegrown Java
• Technical metadata extraction

32. Cocoon
 XML Publishing Framework (Toolbox)
– Generate
• From files (or URLS)
• From databases
• From code (XSP, JSP, PHP)
– Transform
• XSLT
– Serialize
• XML, HTML, PDF, SVG, MIDI?
– Caching

33. XSLT
 Philosophy
– Get data into XML as early in the workflow
as possible
 Flexibility
– Easy to change logic in XSLT
– No need to recompile
 Performance Issues

34. Resources Needed for
FEDORA (Cheap)
 Hardware Requirements
– Minimal for experimentation
• Installs on Windows PC
• Packaged to get up and running quickly
• Demo set of objects
– Scales with hardware in a production
environment

35. Resources Needed for
FEDORA (Expensive)
 1 or More Developers
– 1: Kick the tires
– or More: Real production
 Application Architects
 Requirement Analysts
 Subject Matter Experts
– Articulate requirements
• Object Structure
• Descriptive Metadata

36. Summary
 Five Questions
– Who
– What
– When
– Why
– Where

37. Who
 Institutions with resources to do
software development
 Unique requirements for digital library
software
– Preexisting tools do not fit the need
 Need for integration of existing systems
into one management infrastructure

38. What
 Digital Library Plumbing
 Very general purpose
– Use it to build almost any digital library
application

39. When
 December 10th
Version 1.2

40. Why
 Robust Set of tools to build YOUR
repository
 User support high from FEDORA
development team
 Smart people working on hard problems

41. Where
 www.fedora.info

42. Questions