The OCKHAM NSDL Digital Library Services Registry

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The OCKHAM / NSDLDigital Library Services
Registry

• A Distributed Approach
• To Enable End-to-End
• Digital Service Resolution

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• Funded by the National Science Foundation
• National Science Digital Library Program
• 2 Year Project Funding

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Goals

• Create a Registry for all possible Digital
  Library Services
• Enable End-to-End Digital Library Service
  Resolving

Sub-Goals

• Ensure DLSR is Scalable and Redundant
• Ensure Manageability of DLSR is Scalable
• Use Existing Standards and Technologies

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Use of the DLSR
3 Examples

• Library Portal Use Case
• Metasearch Use Case
• Personal Digital Library

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Distributed DLSR

• The OCKHAM/NSDL DLSR is Distributed
• Many nodes over the network
• Scalability
• Redundancy
• Approach in part based on DNS model

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A Brief History of DNS

• Hosts.txt file (later just hosts)
• ARPAnet started with centralized management
• Inter-NIC
• Eventually, a more manageable approach was needed
• Current Distributed DNS System was created
• Allows De-centralized administration
• Hierarchical design
• Simplifies management
• Reduces bandwith, bottlenecks
• Reduces duplicate name issue (i.e. .edu, .com,
  etc.)

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Distributed DLSR

• Reasoning much the same as DNS
• Similarities and Differences

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Data Layer

• Relational Db OJB
• Synchronized
• Database Interchangeability
• Ease of development
• Lucene
• Fast indexing
• on the fly indexing
• Flexible query engine

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Interface Layer

• Current Interfaces
• Struts powered J2ee interface
• OAICat - OAI-PMH 2.0
• Future Interfaces
• SRU/W
• Z39.50
• OpenURL
• Output Formats
• Html
• XML

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Clients

• Web browser
• OAI-PMH
• Z39.50
• Any web enabled application.

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Network Layer

• JXTA provides low level network functionality
• Peer identification and discovery
• Transport layer
• PeerManager provides modular application level
  functionality
• Load Management
• Client/Server Modules
• Main Registry Modules
• URL Server
• Harvester Client

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Using OAI For Propagating Data

• A peer can query any other peer and receive an
  incremental update
• Queries are based on the latest record
  modification date for the peers local copy of
  the set
• Subsequent queries will use the new latest record
  modification date

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Hierarchal Network Topology

• Topology Requirements
• Data must propagate to all peers
• Compensation for inherent instability of P2P
  networks
• Scalable structure
• Low overhead
• DNS for Digital LibraryServices

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Put the pieces together
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OCKHAM Future

• Expand the DLSR Community and Use
• Explore and build DLSR-aware tools and services
• Prototype semi-automated creation of DLs

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Further Information
OCKHAM Website http//ockham.org
Martin Halbert, Emory mhalber_at_emory.edu
Jeremy Frumkin, Oregon State University
jeremy.frumkin_at_oregonstate.edu