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The OCKHAM / NSDL Digital Library Services Registry

The OCKHAM / NSDL Digital Library Services Registry. A Distributed Approach To Enable End-to-End Digital Service Resolution. Funded by the National Science Foundation National Science Digital Library Program 2 Year Project Funding. Goals.

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The OCKHAM / NSDL Digital Library Services Registry

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  1. The OCKHAM / NSDLDigital Library Services Registry A Distributed Approach To Enable End-to-End Digital Service Resolution

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

  3. 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

  4. Use of the DLSR 3 Examples • Library Portal Use Case • Metasearch Use Case • Personal Digital Library

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

  6. 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.)

  7. Distributed DLSR • Reasoning much the same as DNS • Similarities and Differences

  8. Data Layer Relational Db & OJB • Synchronized • Database Interchangeability • Ease of development Lucene • Fast indexing • “on the fly” indexing • Flexible query engine

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

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

  11. 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

  12. 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 peer’s local copy of the set • Subsequent queries will use the new latest record modification date

  13. 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

  14. Put the pieces together

  15. OCKHAM Future • Expand the DLSR Community and Use • Explore and build DLSR-aware tools and services • Prototype semi-automated creation of DL’s

  16. Further Information OCKHAM Website – http://ockham.org Martin Halbert, Emory – mhalber@emory.edu Jeremy Frumkin, Oregon State University – jeremy.frumkin@oregonstate.edu

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