Focus Research Libraries In Support of Active Learning

1
Focus Research Libraries In Support of Active
Learning

• M. Zubair, K. Maly, and R. Shi
• Department of Computer Science
• Old Dominion University

2
Overview

• Introduction
• Background
• Approach
• Prototype
• Conclusion

3
Motivation

• Digital libraries are important tools used by a
  large number of people in active learning
• Search interfaces of digital libraries vary
  greatly and can lead to confusion
• Lot of redundant work need to be done when
  searching multiple digital libraries
• Most digital libraries are unable to interact
  with each other
• Many digital libraries have proprietary
  architecture and wont change it to
  interoperate with other libraries

4
Introduction

• Tool needed to federate heterogeneous DLs
• Challenges flexibility, transparent to users
• Functions needed exchanging metadata, exchanging
  queries, registration
• Technologies DLDL, XML, RDF, WIDL, LDAP

5
Background

• DL integration and interoperability is essential
• Current approaches
• Same protocol or software suite
• Master service or server-of-servers
• External protocol
• Local Information repository

6
XMLs Role in Interop Digital Libraries

• Extensible Markup Language (XML) used to specify
  a digital library
• Existing libraries only need to describe their
  architecture and do not have to change it
• A new digital library is added by creating an XML
  specification for it

7
XML SPECIFICATION using DLDL

• Structure
• Information on the digital library content
• Access methods of the digital library
• Information to be retrieved from the digital
  library
• DTD
• All XML Specifications have a common Data Type
  Definition (DTD)
• Allows XML parser to check the validity of the
  XML specification and whether it is well formed
• Sample XML Specification for NEEDS (National
  Engineering Education Delivery System)

8
Approach

• Individually Maintenance
  Managers of different digital libraries
  can maintain their own XML specification for
  their library
• Centralized Management
  A centralized LDAP server is used to
  store the dlib names and the URL of the dlib XML
  specification
• Dlib Management
  A Web interface enables dlib to be
  registered with LDAP server, or removed from
  LDAP server. Dlib information can be verified or
  updated.

9
System Architecture
Digital Library (NCSTRL)
Digital Library (NEEDS)
LDAP Server
Internet
Dlib Manager
Search Engine
Web Server
10
Name-Value Pairs stored in LDAP Server
11
Dlib Registration
Web Browser
Display Results
?
Internet
User Request Dlib NameNEEDS Dlib URLhttp//...
?
?
Register Dlib name NEEDS Register NEEDS URL ...
Web Server
?
LDAP Server
Verify Dlib name and URL
12
Dlib Discovery
Web Browser
Display Results
?
Internet
User Request start search engine
?
?
Retrieve Dlib names Retrieve Dlib Specifications
Web Server
?
LDAP Server
Generate Dynamic Page Parse XML doc
13
Prototype and Implementation

• Java Servlet as Search Engine
• Servlet vs. CGI platform independent, start
  once, simultaneously request handling, session
  control, OS authentication, the most flexible
  middle tier
• Servlet vs. Notes Agent better performance,
  write once run anywhere
• SUN XML Parser
• SUN JNDI Package
• Java Naming and Directory InterfaceTM (JNDI) 1.2
• Access LDAP v3 Server

14
FDL server components

• LDAP client
• Manager agent
• XML parser
• Search engine
• Retrieval agent
• Result Processing and Presentation agent

15
Performance Enhancement

• Caching Mechanism
• cache query string and result
• Cache replacement algorithm
• Other Issues
• parse and read in XML specification at initial
  stage
• not wait for all threads finish
• Delete global variables, no thread sleep and
  synchronization

16
System Environment

• Web Server MS IIS 4.0
• Servlet Engine Allaire JRun 2.3
• LDAPv3 Server Netscape Directory Server 4.0

17
Conclusion

• Demos show that dynamic federation of DL is
  feasible and a right direction
• Pending issues usability, metadata mapping,
  scalability, and performance

18
Demo

• Http//dlib.cs.odu.edu

19
Summary

• Future Work
• Questions?