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Mediation and Indexing in P2P-based Information Systems

Mediation and Indexing in P2P-based Information Systems. Super-Peer-based Routing in the Edutella-Network. Overview. Peer-to-Peer Topologies Pure p2p Super peer networks Super-Peers in Edutella P2P Query Routing and Processing Creating the p2p network Relaying queries and results Future

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Mediation and Indexing in P2P-based Information Systems

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  1. Mediation and Indexing in P2P-based Information Systems Super-Peer-based Routing in the Edutella-Network Ingo Brunkhorst

  2. Overview • Peer-to-Peer Topologies • Pure p2p • Super peer networks • Super-Peers in Edutella P2P • Query Routing and Processing • Creating the p2p network • Relaying queries and results • Future • Advanced super-peer topologies Ingo Brunkhorst

  3. Peer-to-Peer Networks P2 P4 P3 P5 P9 P8 P6 P1 P7 Ingo Brunkhorst

  4. Hybrid Networks Files C,D,E P2 P4 Files B,C,D P3 P5 Index P6 Search A File B P1 P7 File A Ingo Brunkhorst

  5. Super-Peer Networks Files C,D,E P2 P4 Files B,C,D P3 A – SP3 BCD – SP2 P5 SP1 SP2 Search A P6 SP3 File B P1 P7 File A Ingo Brunkhorst

  6. Edutella P2P Network • 2 Roles • Information providing role (Provider) • Information consuming role (Consumer) • Implemented in JAVA • Based on JXTA, Sun P2P Architecture • Edutella Common Data and Exchange Model • Java-Model for representing Queries • RDF based Query Language (RDF-QEL-i) • Different levels of expressiveness Ingo Brunkhorst

  7. RDF Resource Description Framework • RDF Statements • Subject – Predicate – Object • RDF Schema • DC – Dublin Core, LOM – Learning Object Metadata • dc:title -> http://purl.org/dc/elements/1.1/title • Example Database • ai.html dc:title „Artificial Intelligence“ • ai.html dc:type „Book“ • ai.html lom:Language „de“ Ingo Brunkhorst

  8. Old Peer Design Provider Peer • Provider Peer • JXTA Pipes for Communication • Edutella Query Service • Connection to Metadata Repository Metadata Repository Database Backend Query Service JXTA Ingo Brunkhorst

  9. New Peer Design • Services • New Roles • Query routing, indexing, provider-peer registration • Topology • Connections between super-peers • HyperCup, Broadcast-Network • Events • Component-based architecture • Modules for communication, processing, indexing, management, statistics • Subsystems send and receive Messages (like Java-AWT,Swing) Ingo Brunkhorst

  10. Super-Peer Implementation Ingo Brunkhorst

  11. Peers joining the Network P3 ai.html dc:title „Artificial Intelligence“ ai.html dc:type „Book“ ai.html lom:Language „de“ Binding Service P4 SP1 LOM P3,P4 dc:title P3 dc:type P3 Indexer SP/P Routing Index Ingo Brunkhorst

  12. BIND - Binding Service • Provider-peers joining and leaving the super-peer network • Provider-peer • Try to find a suitable super-peer • Create a description of the providers capabilities • Send messages to a super-peer • Monitor the state of the super-peer • Super-peer • Maintain a database of all connected provider-peers • Notify the Indexer to update routing indices Ingo Brunkhorst

  13. Indexer • Linked to the Binding Service • Routing indices based on provider descriptions Element Peers Schema LOM P3, P4 Property dc:title P3 Property/Range Classification AI Books ? Ingo Brunkhorst

  14. Constructing SP/SP Index P3 Binding Service LOM P3,P4 dc:title P3 dc:type P3 P4 SP2 SP1 SP/P Routing Index DC SP1 Topology empty SP/SP Routing Index C1 Ingo Brunkhorst

  15. Routing Mechanisms DC P3,P4 lom:Language P3 Router SP/P Index P3 Routing Table Routing Service P4 Processor Query dc:title SP2 Routing Table Router SP/SP Index DC SP2 LOM SP4 Ingo Brunkhorst

  16. ROUTE - Routing Service • Route Queries received from a consumer-peer to connected super-peers and providers • Routing between super-peers based on SP/SP index • Routing to provider-peers based on SP/P index • Characterize Query • Relaying of results Ingo Brunkhorst

  17. QEL - Edutella Query Service • Process Queries received from consumer-peers • Provider-Peer • Resolve using database backend • Re-used code from original Edutella provider peer • Super-Peer • Accept queries from consumers and • Forward queries to routing service Ingo Brunkhorst

  18. Future • Dynamic Indices • Monitoring traffic and query characteristics • Semantic Clustering • Group peers with similar metadata • Peer Trading • Move provider-peers to other super-peers • Advanced Super-Peer Topologies • HyperCup • Mediation • Translating queries between different RDF schemes Ingo Brunkhorst

  19. Mediation • Translate between different RDF schemes • Similar attributes in multiple schemes • Global RDF schema • global:attribute -> peer:attribute LOM P3 lom:Identifier Mediator Query DC global:title P4 dc:title Ingo Brunkhorst

  20. Conclusion • Efficient Query Routing • Routing indices for query routing • Few messages for synchronization • Extendable Peer Design • Event passing interface • Modular concept Ingo Brunkhorst

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