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Evolving Ontologies via P2P technology

Evolving Ontologies via P2P technology. Introduction of a rating method. Purpuse of the visit. Share work See if Trento and VU can cooperate in the future. Outline of this talk. Show some problems in the P2P and Ontology community Show some solutions from literature for each problem

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Evolving Ontologies via P2P technology

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  1. Evolving Ontologies via P2P technology Introduction of a rating method

  2. Purpuse of the visit • Share work • See if Trento and VU can cooperate in the future

  3. Outline of this talk • Show some problems in the P2P and Ontology community • Show some solutions from literature for each problem • Show my solution • Open discussion about the solutions

  4. Problem 1: Queries flooding the network The Gnutella approach from broadcasting queries to all their neighbors is very inefficient. A negative side effect is the inability to find rare items “find the 10th episode of Startrek voyager” Solution: Efficient Peer selection service

  5. Solution 1: Hash ID’s (PASTRY, PAST, CHORD, CAN…) • Make a hash identifier of the content and move the this with the content to the peer(s) which identifier is the closest to the hash identifier • Every peer contains a table of their neighbours Problem: Very efficient routing mechanism, but it can’t handle partial matches and complex queries “find music from britney speers” (what probably must be “find music from britney spears”).

  6. Solution 2: Content replication (Cohen et al., Freenet) • Copy content to places where the queries come from Problem: Result solving instead of cause solving  the problem remains

  7. Solution 3: Keyword reputation (NeuroGrid, Poblano …) • Peers learn and remember content of other peers e.g. Each peer contains a table with peer/keyword pairs accompanied with a rating (Poblano) Problem: A good solution on the mentioned problem. It also could be an algorithm on top of Pastry methods (just for searching and if the hash-id is found, locate the file). However it doesn’t find “All flatscreen monitors with a diameter > 15 inch ”

  8. Problem 2:Variation of ontologies and lack of precision Different peers will use different, though overlapping ontologies. They have to deal with inconsistencies, homonyms, synonyms and sloppy definitions

  9. Solution: Mappings between local ontologies & meaning negotiation • Automatic algorithm of meaning negotiation (Magnini et al.) • Mapping languages (CTXML [Bouquet et al.]) • Metadata infrastructure to annotate data with machine processable knowledge (Edutella [Nejdl, Decker et al.] Problems left: who is right? (even with mapping languages, the mapping is an opinion)

  10. The LARiSSA rating methodology • Backbone of peer is a full-connected, directed graph structured in a class taxonomy • For each statement in the ontology: • Remember source • Remember date • Calculate rating

  11. Problem 3: ontological drift Solution: Add timestamps to (incoming) information, and let them act like a ‘best before’ value (NeuroGrid [Joseph,2002]…in progress…) Problem: How to determine the devaluation function?

  12. Other things:Licencing and dependancy • Open source • Platform dependance (Windows) • Producer dependence (.NET)

  13. Other things:Listen to the users • Don’t think… If we build it, they will come Therefore another characteristic in the compare matrix is the success rate of the described systems

  14. Protocols: Gnutella

  15. Protocols: Gnutella • File sharing protocol • Identifier are IP numbers • Broadcasting queries • When attaching, every peer responds with some information about itself • Own communication language • No security • Implementations: Limewire, Morpheus, Bearshare…

  16. Protocols: JXTA Project

  17. Protocols: JXTA Project • Protocols • Peer Discorvery Protocol (find advertisements of peers) • Peer Resolver Protocol (send and retrieve queries) • Peer Information Protocol (learn about peers’ status) • Peer Membership Protocol (obtain membership reqs) • Pipe Binding Protocol (bind pipe advertisements to pipe endpoint) • Endpoint Routing Protocol (find route between peers) • Unix alike security model, however users are free to implement their own • XML based messages, however YML is easy to implement • Peer monitoring • Platform independent • UUID (128-bit id to refer to an entity like a peer, an advertisement or a service)

  18. Protocols: JXTA Project: examples on JXTA impl. • Aislandagent framework • AllhandsEvent Notification application • AngelopeerrendezvousA p2p based interactive software for intra enterprise communication • GnougatFully decentralised file caching • GnovellaSome experiments with JXTA and document storage in an enterprise • GoA Go Tournament based on the JXTA Protocols • HaluJXTA media distribution application • Instantp2pJXTA Demonstration GUI • JnushareInformation sharing application based on GISP • Juxtaprosea web / discussion content sharing application • jxta-httpdProvides a Set of service & tools provinding web publishing • MyjxtamyJXTA - JXTA Demonstration Application (aka InstantP2P)…

  19. Protocols: FIPA Project • Combination of speech acts, predicate logic and public ontologies • Searching agents in the DF • AP: physical infrastructure in which agents can be deployed • Agent: The fundamental actor on the AP • DF: The yellow pager agent (combinations possible) • AMS: Supervisor of the platform • MTS: Message Transport Service is the default communication method

  20. Protocols: FIPA Project

  21. Protocols: Pastry • 128 bit ID (e.g. hash from IP address) • Hashlist of content moved close to ID • Implementations: • SCRIBEgroup communication/event notification system. • PASTarchival storage systems. • SQUIRRELa co-operative web cache.

  22. Protocols: Pastry

  23. Systems: to be continued… • Neurogrid • Poblano • JXTA • Groove • Magi • Hailstorm • Freenet • Edamok • Edutella • InfoQuilt • InfoSleuth • Jade

  24. Systems: Poblano • On top of JXTA • Based on three components • Codat Confidence (keyword, codatID, flag for local or remote and confidence value) • Peer Confidence (keyword, peerID, confidence value) • Risk (peerID, integrity of codat, accesibility, performance)

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