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Digital Library Architecture and Technology
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Outline
DL architecture Building blocks of DLs DL models Components of DLs DL open source software Modern features in digital library
architectures
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Introduction
DLs contain a variety of materials, technologies, services and standards
The Web itself, LIS centres as well as database providers and vendors are all examples of information services that can play a role in DLs
Digital library architectures provide a view of the underlying structures and frameworks on which DLs are built
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E-journalsOnline
databasesRemote digital
libraries WWW
Search interfaces
Search interfaces
Search interfaces
Search engines&directories
OPACs Search interface
Digital library interface
Users
Local digital library
Libraryresources
Conceptual design of a digital library
Chowdhury (2002) Introduction to digital libraries…
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Components of a DL system
Arms (1997) names the following components for digital libraries:
User interfaces Repository Handle system Search system
6Arms et al. An Architecture for Information in Digital Libraries. D-Lib Magazine, February 1997.
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User interfaces
User interface for end-users to get access to the library and its collections
User interface for librarians and system administrators who manage collections
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Repository
Repositories store and manage digital objects and other information. A large digital library may have many repositories of various types, including modern repositories, legacy databases, and Web servers.
The repository access protocol (RAP). Is used to recognize the rights and permissions that need to be satisfied before a client can access a digital object.
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Handle system
Handles are general purpose identifiers that can be used to identify digital objects, over long periods of time and to manage materials stored in any repository or database.
DOI: Digital Object Identifiers Example: 10.1234/NP5678
10.5678/ISBN-0-7645-4889-4
Persistent Uniform Resource Locator (PURL) developed by OCLC – names the location of an object
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Search system
There will be many indexes and catalogs in a digital library that can be searched to discover information before retrieving it from a repository.
These indexes may be independently managed and support a wide range of protocols.
Databases, information retrieval systems, and content management systems are examples
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CRADDL architecture
Cornell Reference Architecture for Distributed Digital Libraries (CRADDL - pronounced "cradle"), a set of components that form the core of a digital library infrastructure.
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CRADDL architecture
Content in the architecture is stored in the form of digital objects
The repository service provides the mechanisms for the deposit, storage, and access to digital objects
Digital Objects are identified by unique URNs The index service provides the mechanism for
discovery of digital objects via query The collection service provides the mechanisms for
the aggregation of access to sets of digital objects User interface services or gateways provide human-
centered entry points to the functionality of the digital library
15 CRADDL services
16Repository Services
Components of a Digital Library
Collection Services
Index Services
PersistentNAMES
NameService
UserInterfaceGateway
DigitalObjects
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Alexandria DL architecture
One of the six projects funded under the Digital Libraries Initiative (DLI),
A digital library of geospatial information, based at the University of California, Santa Barbara
Several databases, gazetteers and thesaurus
Sophisticated architecture
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Alexandria Digital Library
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Alexandria DL architecture
A three-tier model consisting of:ServersMiddlewareClients
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Alexandria DL architecture
Servers: maintain collections of metadata describing the library’s holdings and for implementing query and retrieval mechanisms
Middleware: performs standard service on these collections
Clients: search sessions, list the library collections, retrieve metadata, and holdings
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Client
QueryMapping
RetrievalMapping
DatabaseAccess
AccessControl
( AO Lserver)
client
servers
( libm i) / SQL
SQL
KNF
MapGenerator
HTTP/ m apbrow ser
m iddlew are
SessionLog
UserDatabase
log record
log record
user I D
session I D
QueryFanout
ResultMerge
... ...
HTTP/session , search, holdings,
collections, m etadata
Gazetteer DBMS
QueryView
RetrievalView s
( I nformix)
Catalog DBMS
QueryView
RetrievalView s
( I nform ix)
Gatew ay
QueryView
RetrievalView s
(e.g. Z39.50)
?
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DL open source software
Greenstone Fedora D-space Eprint
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Greenstone
An open-source multilingual application developed by the New Zealand Digital Library Project at the University of Waikato
Developed and distributed in cooperation with UNESCO and the Human Info NGO.
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Greenstone features
Accessible through web browsers Full text and fielded search Browsing facilities Facility to add DC metadata Multimedia collections Can support millions of documents Collections can be published on CD-
ROM
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Fedora
Flexible tools for managing and delivering digital content.
Jointly developed by Cornell University and the University of Virginia Library
National Science Digital Library (NSDL) uses Fedora
It supports the DC metadata format It can run on MySQL and Oracle
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DSpace digital repository system Jointly developed by MIT Libraries and
Hewlett-Packard Labs Stores, indexes, preserves, and distributes
digital research material. Various applications: Institutional
Repositories, Learning Object Repositories (LORs), eTheses , Electronic Records Management (ERM), Digital Preservation, Publishing
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EPrints
Was developed at the University of Southampton, released in late 2000
The objective was to facilitate open access to peer-reviewed research and scholarly literature
EPrints serves as an archive for other electronic documents such as images and audio.
Currently installed in more than 241 institution.
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Modern Features in Digital Library Architectures
Social networking sites
Social networking, bookmarking and tagging
Reviews Recommendation features Citation and reference linking Bibliometric tools
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Hull, D., Pettifer, S. R., and Kell, D. B. (2008). Defrosting the digital library: Bibliographic tools for the next generation web. PLoS Comput Biol, 4(10):e1000204+.
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Tag 1Tag 2Tag 3
Tag 1Tag 2Tag 3
Tag 1Tag 2Tag 3
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Social Tagging Environment
Photo sharing
Slide sharing
Videoblogging and sharing
Social networks
Academic bookmarking
Bookmarking
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Citationlinking
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Get it! Citation linker
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Examples
Greenstone: http://www.greenstone.org/examples Fedora:
Tufts University: http://dl.tufts.edu/ University of Viginia:
http://www.lib.virginia.edu/digital/collections/ DSpace
U of A: http://repository.library.ualberta.ca/dspace/index.jsp U of Wolverhampton(UK) :
http://wlv.openrepository.com/wlv/ Queen’s University: https://qspace.library.queensu.ca
EPrints British Library: http://sherpa.bl.uk/ E-LIS: http://eprints.rclis.org/ History and Theory of Psychology: http://htpprints.yorku.ca/