Digital Libraries INFO 653 Week 5 Digital Objects and Repositories Xia Lin College of Information Science and Technology Drexel University

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Digital LibrariesINFO 653Week 5Digital Objects
and RepositoriesXia LinCollege of Information
Science and TechnologyDrexel University
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To be more precise

• Assignment 5 due in one week or two weeks?
• Grade due for graduating students
• Friday June 8th
• Your paper due June 6
• Everyone
• Presentation June 6
• Final Paper due June 13

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This Weeks Topics

• Logical Layers and Technical structures of
  Digital Libraries
• Repositories and collections
• DSpace and Fedora
• Institutional Repositories
• NSDL Architecture

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Logical layers of DL

• Digital Objects
• Handles
• Digital Repositories
• Collections
• Control zones
• Digital Libraries
• Information Space

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Digital Objects

• A digital object is a fundamental unit of the
  digital library
• Digital materials identified by a Key or a
  metadata
• A digital object is not necessary a digital
  work
• Users often want to refer to items at a higher
  level of abstraction than a file or a object

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Digital Objects

• A document is a digital object.
• Is a figure in a document an Object?
• If not, can you search for the figure?
• In database, it differentiates entities and weak
  entities.
• Should we called the figure weak object?
• What is the book in a digital library?
• Is Digital object the book of digital
  libraries?

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CDL Guidelines for Digital Objects

• Basic Level
• METS (METS Diagram)
• Unique identifier, fileSec, profiles
• Metadata
• Descriptive metadata
• Technical metadata
• Content files
• Text, Images, audio

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• Enhanced level
• In addition to basic level
• Links
• Content type
• Metadata
• Provide the most granular and richest metadata
  possible
• Right management administrative metadata
• Character Encoding

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Comparisons of Objects to Books

• Are all the objects information resources?
• Are objects selected on the basis of quality?
• Are objects located in the logical place?
• How are objects organized?
• Are objects subjected to authority control?
• Are objects permanent (do not disappear)?
  

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Handle

• General purpose persistent identifier
• to identify digital objects over long periods of
  time.
• to assist management of repository database.
• Functions of classification system barcodes ?
• Work across different repositories and databases
• Expansion of domain names ?

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The Handle System

• The Handle System is a general-purpose global
  name service that allows secured name resolution
  and administration over the public Internet.
• The Handle System manages handles, which are
  unique names for digital objects and other
  Internet resources.

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Handle System

• Also called Uniform Resource Names (URNs)
• A open set of protocols,
• a namespace, and
• an implementation of the protocols
• Web-wide resolution and administration
• Global Handle Registry (GHR)
• Local Handle Service (LHS)
• Handle specific namespaces

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Example
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Problems

• The Handle system works on technical level, not
  on semantic level
• It is not a (content) classification system.

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Digital Collections

• Three levels of services
• Digital Libraries
• Digital Collections
• Digital Repositories

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• Repositories
• Provide the mechanisms for the deposit, storage
  and access to digital objects
• Collections
• Provide the mechanisms for the aggregation of
  access
• Include various indexing services
• Digital Libraries
• Include user interface and user services

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Digital Libraries
User
User Service
User Interface
Searching
Collaborating
Browsing
Collection
Index
Index
Repository
Repository
Repository
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Defining a Collection

• A collection is logically defined as a set of
  criteria for selecting resources from the broader
  information space.
• A collection provides a tools for indexing,
  management, and resource discovery.

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Defining a Repository

• A repository must have its own collection of
  digital objects.
• Is a collection of all links a repository?
• Yes, it is.
• Yes, if it has controls over the contents and
  availability of the links.
• Yes, if it has a clearly defined control zone.
• No.

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• A repository can claim having a collection
• if it can be defined logically (not necessary
  physically).
• if it has agreements/contracts with resource
  providers.
• If it has certain control of the access and
  quality.

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DSpace

• Originally designed for a course repository by
  MIT and HP, now an open-source software
• Repositories are organized by collections indexed
  automatically
• Communities and groups can be set up for users
• The Web-based interface allows users directly
  interact with the system to store, index, and
  search the repository.

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DSpace at Drexel

• For the Library
• http//dspace.library.drexel.edu/
• For this course
• http//www.cis.drexel.edu/dspace/

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Fedora

• Flexible Extensible Digital Object Repository
  Architecture.
• Powerful digital object models
• Extensible metadata management
• Digital objects exist within a repository
  architecture that supports a variety of
  management functions
• Web service integration
• All functions of Fedora, both at the object and
  repository level, are exposed as web services.
• Distributed Repositories
• Users interact with repositories through Web
  services.
• OAI-PMH conformance
• Configurable security architecture

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Fedora

• Focusing on digital object management
• Provide persistent identifiers
• Support descriptions of relationships among
  objects
• Allow heterogeneous content and metadata based on
  an extensible object model
• Object reusability
• Scalability and security
• Standard, interoperable access

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Comparison of Fedora and Dspace
Fedora DSpace
Technology Client-server Web-based
Architecture Forward looking Application-oriented
Implementation Java objects Java, non-modules
Metadata METS-based Dublin Core
Interface Not fully developed Easy to use
Extendibility Excellent Moderate
Searching Moderate Excellent
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Other Repository Systems

• EPRINTS
• http//software.eprints.org/
• BePress (Berkeley Electronic Press)
• http//www.bepress.com/
• University of Californias E-Scholarship
  repository (http//escholarship.cdlib.org/)
• Greenstone
• http//www.greenstone.org/

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Digital Library Architecture

• Technical Architecture
• System architecture
• Network architecture
• Content Architecture
• Contexts and Contributions
• Content Organization (next week)

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DL Architecture

• Service Architecture
• A Service Framework for Libraries
• A service framework is a set of reference
  models, along with a set of concepts and
  vocabulary for expressing and relating them. The
  service framework i.e., vocabulary and
  reference models covers the range of entities
  relevant to the articulation of library business
  goals at varying levels of granularity, as well
  as the services that support these goals.

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MODELS

• MOving to Distributed Environments for Library
  Services

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NSDL Library Architecture
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NSDL Data Repository

• Metadata from NSDL projects and open-access Web
  resources
• Interact with
• Learning standards
• Right management services
• Search services
• STEM Collections

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NSDL Phrase 2

• Information modeling for Complexity and context
• Capturing opinions, comments, and reviews about
  library resources and their history of use.
• Describing the community of users involved in the
  creation of a learning object.
• Capturing learner interactions and connecting
  their profiles to learning objects.
• Tracking and storing the search keywords that led
  to eventual use of the resource.

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Information Network overlay
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OAIster
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Conclusions

• Digital library Architectures should be defined
  in several points of views
• Technical
• Content
• Services

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Control Zone

• A library, digital or otherwise, is always a
  highly selective subset of available information
  objects, segregated and favored, to which access
  is enhanced.
• The Web is an open zone, and a digital library is
  a control zone.

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Features of Control Zone

• Core definition
• Particularization (Specialization)
• Maintenance
• Certification
• Standardization

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Institutional Repository

• A digital collection capturing and preserving the
  intellectual output of a organization or a
  community
• Institutionally defined
• Scholarly
• Cumulative perpetual
• Open and interoperable

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IR

• A set of services for the management and
  dissemination of digital materials created by the
  institution and its community members.
• Self-archiving
• Organizational commitment
• Long-term preservation

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Use of IR

• Scholarly communications
• Storing learning materials, courseware, and
  research papers
• Managing collections of research documents
• Encouraging open access to scholarly research