The Real-time Web in the Age of Agents
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The document discusses the emergence of real-time interaction on the Semantic Web through the use of Semantic Web agents. It describes how agents can be used to enable real-time querying and subscription to data streams with provenance tracking. The RDFAgents specification extends standards for agent communication to support these capabilities. Examples of use cases involving question answering, query delegation, real-time data updates, and syndication are provided to illustrate how agents can facilitate real-time interaction on the Semantic Web.
The Real-time Web in the Age of Agents
- 1. Joshua Shinavier The Real-Time Web in the Age of Agents 2011 Semantic Technology Conference June 8th, 2011
- 2. Overview • real-time Semantic Web is emerging • state of the art • real-time interaction? • Semantic Web agents • use cases • the RDFAgents specification • queries and subscriptions • data model • provenance and information discovery 2
- 3. Real-time interaction with the Semantic Web • let’s mash up the “real-time” social Web with the Semantic Web • data sources are plentiful • e.g. Twitter, Facebook, Glue, ActivityStreams • data integration is straightforward • mapping into Semantic Web vocabularies • linking into Semantic Web datasets • what about interaction? 3
- 4. Semantic Web “1.0” was • ...not “real-time” - static RDF data, occasionally updated • ...not ubiquitous - desktop model (browsers, keyword search) - client-server model • ...not very interactive - read-only content, monolithic triple stores - little “bottom-up” user content 4
- 5. Getting closer to “real-time” static triple stores days web pages hours blogs minutes microblogs TwitLogic seconds instant messaging sparqlPuSH C-SPARQL milliseconds streaming media latency technology misc. examples 5
- 6. More ubiquitous, more interactive • mobile Semantic Web - e.g. RDF On the Go, Android Semantic Web Core library, DBpedia/mSpace/OntoWiki Mobile • semantic sensor networks • semantic publishing and presence - e.g. SMOB, Sharing Spaces • smart spaces, dialogue-based Semantic Web UI 6
- 7. The 10,000-foot view • real-time Semantic Web is growing organically • common themes: - rapidly changing data - two-way, peer-to-peer communication - participation of “ubiquitous” devices large and small • we need shared frameworks for real-time interaction 7
- 8. Enter Semantic Web agents “The real power of the Semantic Web will be realized when people create many programs that collect Web content from diverse sources, process the information and exchange the results with other programs. The effectiveness of such software agents will increase exponentially as more machine-readable Web content and services becomes available.” — Tim Berners-Lee et al., 2001 8
- 9. By “agent”, we mean: • peer-to-peer communication • proactive, event-driven information sharing • conventions for provenance tracking • support for a variety of interaction protocols - e.g. for query answering, subscriptions, contracts ( not that kind of agent. ) 9
- 10. Use cases: basic query answering • Agent A → Agent B: “Who is Josh?” • Agent B → Agent A: “Josh is a presenter at SemTech.” 10
- 11. Use cases: query delegation with provenance • Agent A → Agent B: “Who is Josh?” - Agent B → Agent C, Agent D: “Who is Josh?” - Agent C → Agent B: “Josh is a presenter at SemTech.” - Agent D → Agent B: “Josh has the Twitter handle @joshsh and has written these tweets: ...” • Agent B → Agent A: “Agent C says that Josh is a presenter at SemTech. Agent D says that Josh has the Twitter handle @joshsh and has written these tweets: ...” 11
- 12. Use cases: real-time data streams • Agent A → Agent B: “Keep me up to date about SemTech.” • Agent B → Agent A: “Will do!” • Agent B → Agent A: “Josh has just written this tweet about SemTech: ...” • Agent B → Agent A: “Craig has just posted this review of SemTech: ...” 12
- 13. Use cases: syndication with provenance • Agent A → Agent B: “Keep me up to date about SemTech.” • Agent B → Agent A: “Will do!” - Agent B → Agent C: “Keep me up to date about SemTech.” - Agent C → Agent B: “Will do!” - Agent C → Agent B: “Josh has just written this tweet about SemTech: ...” • Agent B → Agent A: “Agent C says that Josh has just written this tweet about SemTech: ...” 13
- 14. Why agents? Extreme real-time • human limit of real-time ≈ 10 - 100ms - these are simultaneity thresholds, central to human sensory integration • technical limits of real-time are similar - 134ms for a round-trip around the Earth (ideally) - 28ms from New York to San Francisco and back - actual Internet latency is 2 to 3 times higher, but • TCP’s three-way handshake is a problem - we need long-lived connections and bidirectional data flow, as in XMPP (Jabber) 14
- 15. Why agents? The standards • FIPA (Foundation for Intelligent Physical Agents) • most widely-adopted body of agent standards • supports peer-to-peer, asynchronous, and event- driven communication • transport agnostic - compatible with HTTP, XMPP, etc. • easily coupled with Web APIs, Semantic Web data formats 15
- 16. RDFAgents = + data streams • RDFAgents specification • extends FIPA • enables query answering and real-time data streams with provenance • includes: • RDF content languages • two interaction protocols: Query and Pub-Sub • support for trust, privacy, information accountability • conventions for peer-to-peer information discovery 16
- 17. Queries 17
- 18. Subscriptions 18
- 19. message type Example: a message (inform-ref sender and :sender (agent-identifier :name http://example.org/twitlogic receiver ! :addresses (sequence xmpp:twitlogic@example.org)) :receiver (set (agent-identifier :name http://example.org/consumer ! :addresses (sequence xmpp:consumer@example.org))) :protocol fipa-subscribe :conversation-id c976b710a5 :language rdf-trig “conversation” :content " metadata @prefix dc: <http://purl.org/dc/terms/> . @prefix ex: <http://example.org/> . @prefix sioc: <http://rdfs.org/sioc/ns#> . RDF dataset @prefix sioct: <http://rdfs.org/sioc/types#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . { ex:post1785782813 a sioct:MicroblogPost ; dc:title "#SemTech begins again!" ; dc:created "2011-06-06T19:43:35.000Z"^^xsd:dateTime ; sioc:topic <http://twitlogic.fortytwo.net/hashtag/semtech> . }") 19
- 20. RDFAgents data model • agents exchange RDF Datasets, in the sense of SPARQL - any number of Named Graphs - may be annotated with provenance metadata - a single default graph - contains asserted (accepted) statements • agents identify themselves with Semantic Web URIs - agent contact information in FOAF • Semantic Web Publishing vocabulary captures the provenance trail 20
- 21. Example: a dataset from a message a named graph generic content <urn:uuid:be0c72c6-2b8f-4134-b309-690039f8c419> { ex:post1785782813 a sioct:MicroblogPost ; dc:title "#SemTech begins again!" ; dc:created "2011-06-06T19:43:35.000Z"^^xsd:dateTime ; sioc:topic <http://twitlogic.fortytwo.net/hashtag/semtech> . } the default graph (accepted statements) { <urn:uuid:be0c72c6-2b8f-4134-b309-690039f8c419> a rdfg:Graph ; swp:assertedBy <urn:uuid:be0c72c6-2b8f-4134-b309-690039f8c419> ; swp:authority ex:twitlogic . ex:twitlogic a foaf:Agent ; foaf:mbox <xmpp:twitlogic@example.org> . } graph metadata agent metadata 21
- 22. The provenance trail • keeping track of who said what - publishers deserve credit for their content - consumers need to decide what to believe • RDFAgents specifies a provenance-preserving transformation for each dataset received - records “A said that B said X” relationships between agents and graphs • simple policies unravel the provenance trail to accept or reject RDF statements • provenance metadata also supports information discovery 22
- 23. What can you do with RDFAgents? • make real-time streams out of social data sources - e.g. Twitter agents, ActivityStreams agents, etc. • combine streams from different sources • integrate with Web services, Linked Data and SPARQL endpoints • attach SPARQL-based filters for smart content feeds • pipe the data into a triple store, publish it as Linked Data, power your real-time applications 23
- 24. RDFAgents implementation • implemented in Java with JADE and Sesame - LEAP kernel for mobile devices - all of the usual RDF formats incl. TriG, N-Quads - transport protocols: XMPP, HTTP, IIOP • open-source • in progress: high-throughput RDF data streams with AllegroGraph • in progress: Droidspeak library for Android OS ( ) 24
- 25. Conclusion • Semantic Web is moving into real-time and ubiquitous environments, but • common interaction models are needed • Semantic Web agents are particularly appropriate • RDFAgents = Semantic Web + FIPA for transport- agnostic, peer-to-peer queries and data streams with provenance 25
- 26. Thanks! • RDFAgents: • http://fortytwo.net/2011/rdfagents/spec • https://github.com/joshsh/rdfagents • Tetherless World Constellation: http://tw.rpi.edu • Franz Inc: http://www.franz.com • Institute of Automation: http://english.ia.cas.cn • TinkerPop: http://tinkerpop.com • Contact: • josh@fortytwo.net, @joshsh 26