DIR workshop ontology stream data access
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    DIR workshop ontology stream data access DIR workshop ontology stream data access Presentation Transcript

    • Data Intensive Research Workshop Edinburgh, UKOntology-based Access to Streaming Data Sources Jean-Paul Calbimonte Ontology Engineering Group Facultad de Informática, Universidad Politécnica de Madrid. jp.calbimonte@upm.es Date: 16/02/2011
    • Introduction & Scope• Sensor technologies • Ubiquitous data capture • Data processing • Cheap • Noisy, Unreliable • Low computational, power resources, storage• Streaming Data • Continuously appended data (t9, a1, a2, ... , an) • Potentially infinite (t8, a1, a2, ... , an) • Time-stamped tuples Streaming (t7, a1, a2, ... , an) ... • Continuous queries Data ... • Changes of values over time (t1, a1, a2, ... , an) • Latest used in queries ... ... • Applications in security surveillance, healthcare provision, environmental monitoring, you name it.Enabling Ontology-based Access to Streaming Data Sources 2
    • Motivation Flood risk alert: South East England Wave, Real-time Wind, data Tide Emergency planner Meteorological forecasts Flood defences data ... ... Other sources ... • Detect conditions likely to cause a flood • Present data model in terms of the user domain: e.g. Flood risk assessment Example: • “provide me with the wind speed observations average over the last minute in the Solent region, if it is higher than the average of the last 2 to 3 hours”Enabling Ontology-based Access to Streaming Data Sources 3
    • Motivation• Ontologies can be used as such a common model • Achieve logical transparency in access to data. • Hide to the user where and how data are stored. • Present to the user a conceptual view of the data. • Use a semantically rich formalism for the conceptual view. [Calvanese2007]• Need to provide solution for: • Establish mappings between ontological models and streaming data source schemas • Access streaming data sources through queries over ontology modelsEnabling Ontology-based Access to Streaming Data Sources 4
    • Background – Ontology-based Data AccessGenerate Semantic Web content from existing relational data sources Linked Data RDF Ontological Models R2O + ODEMapster e.g. SPARQL D2RQ SquirrelRDF RDBToOntoOntology-based Relational.OWL Data Access Query/Data SPASQL Transformation Mapping Document Virtuoso MASTRO e.g. SQL Relational Schemas Enabling Ontology-based Access to Streaming Data Sources 5
    • Web of DataEnabling Ontology-based Access to Streaming Data Sources 6
    • Background – Querying Relational Data StreamsStreaming Data Event Streams/Acquisitional Streams STREAM Aurora/Borealis Cougar Query engines e1 WINDOW [tnow TO tnow-2] SLIDE 1 TinyDB SNEE e1 e2 CQL SNEEql Query languages TinyQL e1 e2 e3 Transform infinite sequence e1 e2 e3 e4 of tuples to bounded bag t t+1 t+2 t+3 t+4 t+5 Window-to-Stream operators: ... convert stream of windows to stream of tuples ...Enabling Ontology-based Access to Streaming Data Sources 7
    • Ontology-based Streaming Data Access SPARQLStream algebra(S1 S2 Sm) q Query translation SNEEql Sensor SPARQLStream (Og) Network (S1) Relational Client Stream-to-Ontology DB (S2) Query Evaluator mappings Stream Engine (S3) RDF Store [tuples] (Sm) Data [triples] translation Ontology-based Streaming Data Access ServiceEnabling Ontology-based Access to Streaming Data Sources 8
    • Ontology-based Streaming Data Access• Mappings from relational streams to ontological concepts • Extend stored data schema mappings • Study translation semantics• Provide with a stream query language at ontological level • Use notion of RDF stream • Extend SPARQL • Window operator, window-to-stream operatorsEnabling Ontology-based Access to Streaming Data Sources 9
    • SPARQLStream• RDF-Stream ... ... ( <si-1,pi-1, oi-1>, ti-1 ), ( <si, pi, oi>, ti ), ( <si+1,pi+1, oi+1>, ti+1 ), ... ...Example:• “provide me with the wind speed observations over the last minute in the Solent Region ” STREAM cd:Observation <http://www.semsorgrid4env.eu/ccometeo.srdf> ... cd:observationResult ... ( <ssg4e:Obs1,rdf:type, cd:Observation>, ti ), xsd:double ( <ssg4e:Obs1,cd:observationResult,”34.5”>, ti ), ( <ssg4e:Obs2,rdf:type, cd:Observation>, ti+1 ), ( <ssg4e:Obs2,cd:observationResult,”20.3”>, ti+1 ), ... ... Enabling Ontology-based Access to Streaming Data Sources 10
    • SPARQLStream Example: • “provide me with the wind speed observations over the last minute in the Solent Region ” PREFIX cd: <http://www.semsorgrid4env.eu/ontologies/CoastalDefences.owl#> PREFIX sb: <http://www.w3.org/2009/SSN- cd:Observation XG/Ontologies/SensorBasis.owl#> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>cd:observationResult SELECT ?windspeed ?windts cd:observedProperty FROM STREAM <http://www.semsorgrid4env.eu/ccometeo.srdf> [ NOW – 1 MINUTE TO NOW MINUTES ] xsd:double WHERE cd:Property { ?WindObs a cd:Observation; cd:featureOfInterest cd:observationResult ?windspeed; cd:observationResultTime ?windts; cd:observedProperty ?windProperty; cd:Feature cd:featureOfInterest ?windFeature. ?windFeature a cd:Feature; cd:locatedInRegion cd:SolentCCO. ?windProperty a cd:WindSpeed. cd:locatedInRegion } cd:Region Enabling Ontology-based Access to Streaming Data Sources 11
    • Ontology-based Streaming Data Access SPARQLSream algebra(S1 S2 Sm) q Query translation SNEEql Sensor SPARQLSream (Og) Network (S1) Relational Client Stream-to-Ontology DB (S2) Query Evaluator mappings Stream Engine (S3) RDF Store [tuples] (Sm) Data [triples] translation Ontology-based Streaming Data Access ServiceEnabling Ontology-based Access to Streaming Data Sources 12
    • S2O Mappings<conceptmap-def id="Observation_wind"name="http://www.semsorgrid4env.eu/ontologies/CoastalDefences.owl#Observation"virtualStream="http://www.semsorgrid4env/ccometeo.srdf"> <uri-as> <operation oper-id="concat"> <arg-restriction on-param="string1"> <has-value>http://www.semsorgrid4env.eu/data#ObservationWind</has-value> </arg-restriction> <arg-restriction on-param="string2"> <has-column>meteostream.DateTime</has-column> </arg-restriction> </operation> </uri-as><attributemap-defname="http://www.semsorgrid4env.eu/ontologies/CoastalDefences.owl#observationResult"dataType="xsd:double"><selector><aftertransform> cd:Observation <operation oper-id="constant"> <arg-restriction on-param="const-val"> meteostream <has-column>meteostream.Hs</has-column> Datetime: long </arg-restriction> cd:observationResult Hs : float Lon: float </operation> Lat: float</aftertransform> xsd:double</selector></attributemap-def> Enabling Ontology-based Access to Streaming Data Sources 13
    • S2O Mappings • Union of extents-streams envdata_rhylflats Datetime: long Hs : float Lon: float Lat: float U envdata_milford <union name="meteostream"> Datetime: long cd:Observation Hs : float <map value="http://www.semsorgrid4env.eu/ontologies/ Lon: float CoastalDefences.owl#SolentCCO"> Lat: float U <extent name="envdata_hornsea"></extent> cd:observationResult envdata_hornsea <extent name="envdata_rhylflats"></extent> Datetime: long <extent name="envdata_milford"></extent> Hs : float <extent name="envdata_westbay"></extent> Lon: float xsd:double Lat: float </map> U </union> envdata_westbay Datetime: long Hs : float Lon: float Lat: floatEnabling Ontology-based Access to Streaming Data Sources 14
    • Ontology-based Streaming Data Access SPARQLSream algebra q Query translation SNEEql Sensor SPARQLSream (Og) Network (S1) Relational Client Stream-to-Ontology DB (S2) Query Evaluator mappings Stream Engine (S3) RDF Store [tuples] (Sm) Data [triples] translation Ontology-based Streaming Data Access ServiceEnabling Ontology-based Access to Streaming Data Sources 15
    • Query Translation• Queries: SELECT ?y WHERE { ?x a cd:Observation; cd:observationResult ?y. } SELECT ?y FROM STREAM < STREAM <http://www.semsorgrid4env.eu/ccometeo.srdf> [ NOW – 1 MINUTE TO NOW MINUTES ] > WHERE { ?x a cd:Observation; cd:observationResult ?y. } Enabling Ontology-based Access to Streaming Data Sources 16
    • Query Translation• Mappings: query algebra expression over sources cd:Observation envdata_milford Datetime: long cd:observationResult Hs : float Lon: float Lat: float xsd:double Datetime Hs envdata_milford Enabling Ontology-based Access to Streaming Data Sources 17
    • Query Translation envdata_rhylflats Datetime: long Hs : float Lon: float Lat: float cd:Observation U envdata_milford Datetime: long Hs : float cd:observationResult Lon: float Lat: float U envdata_hornsea xsd:double Datetime: long Hs : float Lon: float DateTime Lat: float Hs U envdata_westbay Datetime: long Hs : float Lon: float Lat: float DateTime DateTime DateTime DateTime Hs Hs Hs Hs envdata envdata envdata envdata _rhylflats _milford _hornsea _westbayEnabling Ontology-based Access to Streaming Data Sources 18
    • Ontology-based Streaming Data Access SPARQLSream algebra q Query translation SNEEql Sensor SPARQLSream (Og) Network (S1) Relational Client Stream-to-Ontology DB (S2) Query Evaluator mappings Stream Engine (S3) RDF Store [tuples] (Sm) Data [triples] translation Ontology-based Streaming Data Access ServiceEnabling Ontology-based Access to Streaming Data Sources 19
    • Query Execution envdata_westbay Ontologies Feature envdata_chesil Streams Observation locatedIn Region v envdata_milford hasObservation Result S2O v Mapping envdata_hornsea observed Property Region v xsd:float envdata_rhylflats v Timestamp: long WaveHeight Hs : float Property Lon: float Lat: floatPREFIX cd: <http://www.semsorgrid4env.eu/ontologies/CoastalDefences.owl#>PREFIX sb: <http://www.w3.org/2009/SSN-XG/Ontologies/SensorBasis.owl#>PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>SELECT ?waveheight ?wavets ?lat ?lonFROM STREAM <http://www.semsorgrid4env/ccometeo.srdf>WHERE{ (SELECT Lon,timestamp,Hs,Lat FROM envdata_rhylflats) UNION ?WaveObs a cd:Observation; (SELECT Lon,timestamp,Hs,Lat FROM envdata_hornsea) UNION cd:observationResult ?waveheight; (SELECT Lon,timestamp,Hs,Lat FROM envdata_milford) UNION cd:observationResultTime ?wavets; (SELECT Lon,timestamp,Hs,Lat FROM envdata_chesil) UNION cd:observationResultLatitude ?lat; (SELECT Lon,timestamp,Hs,Lat FROM envdata_perranporth) UNION cd:observationResultLongitude ?lon; (SELECT Lon,timestamp,Hs,Lat FROM envdata_westbay) UNION cd:observedProperty ?waveProperty; (SELECT Lon,timestamp,Hs,Lat FROM envdata_pevenseybay) cd:featureOfInterest ?waveFeature. ?waveFeature a cd:Feature; cd:locatedInRegion cd:SouthEastEnglandCCO. ?waveProperty a cd:WaveHeight. } SPARQLStream SNEEql Enabling Ontology-based Access to Streaming Data Sources 20
    • Ontology-based Streaming Data Access SPARQLSream algebra q Query translation SNEEql Sensor SPARQLSream (Og) Network (S1) Relational Client Stream-to-Ontology DB (S2) Query Evaluator mappings Stream Engine (S3) RDF Store [tuples] (Sm) Data [triples] translation Ontology-based Streaming Data Access ServiceEnabling Ontology-based Access to Streaming Data Sources 21
    • Data Translation• Data translation: Tagged tuples SPARQL bound variables <ns9:sparql> waveheight wavets <ns9:head> <ns9:variable name="waveheight"/> 4.850 1272588663 <ns9:variable name="wavets"/> </ns9:head> 2.1230 1272587400 <ns9:results> <ns9:result> <ns9:binding name="waveheight"> <ns9:literal datatype="http://www.w3.org/2001/XMLSchema#double">4.850</ns9:literal> </ns9:binding> <ns9:binding name="wavets"> <ns9:literal datatype="http://www.w3.org/2001/XMLSchema#long">1272588663</ns9:literal> </ns9:binding> </ns9:result> <ns9:result> <ns9:binding name="waveheight"> <ns9:literal datatype="http://www.w3.org/2001/XMLSchema#double">2.1230</ns9:literal> </ns9:binding> <ns9:binding name="wavets"> <ns9:literal datatype="http://www.w3.org/2001/XMLSchema#long">1272587400</ns9:literal> </ns9:binding> </ns9:result> </ns9:results> </ns9:sparql>
    • R2RML Mappings • W3C RDB2RDF Working Group • :waveObsResult rr:predicateMap [ rr:predicate ssg:observationResult ]; • rr:objectMap [ rr:column "Hs" ]. • :waveObsTime rr:predicateMap [ rr:predicate ssg:observationResultTime ]; • rr:objectMap [ rr:column "timestamp" ]. • :waveFoISea rr:predicateMap [ rr:predicate ssg:featureOfInterest ]; • rr:objectMap [ rr:object ssg:Sea ]. • :waveObsProp rr:predicateMap [ rr:predicate ssg:observedProperty ]; • rr:objectMap [ rr:object ssg:WaveHeight ]. • • :MilfordWaveObservation a rr:TriplesMapClass; • rr:SQLQuery ""; • rr:subjectMap [ rr:column "envdata_milford.DateTime"; rr:class ssg:Observation; rr:graph ssg:ccometeo.srdf ]; • rr:tableName "envdata_milford"; • rr:predicateObjectMap :waveObsResult; • rr:predicateObjectMap :waveObsTime; • rr:predicateObjectMap :waveFoISea; • rr:predicateObjectMap :waveObsProp;Enabling Ontology-based Access to Streaming Data Sources 23
    • SemSorGrid4Env EU Project 1. Universidad Politécnica de Madrid, (UPM, Spain) 3 2. University of Manchester (UNIMAN, UK) 3. National and Kapodistrian University of Athens (NKUA, Greece) 3 1 4. University of Southampton (SOTON, UK) 5. Deimos Space SLU (DMS, Spain) 6. EMU Ltd. (EMU, UK) 7. TechIdeas (TI, Spain) 24Enabling Ontology-based Access to Streaming Data Sources 24
    • Project Challenges • Integrated information space • Rapid development • Discovery new sensor networks • flexible and user-centric decision • Integrate with existing ones support systems • Integrate possibly other data sources • Use data from multiple (e.g., historical databases) autonomous independently deployed sensor networks and other applications. 100 80 th in   a p p lic a tio n s ( m a s h u p s ) m id d le w a re 60 Este 40 s e m a n tic   d a ta   in te g ra tio n   a n d   q u e ry in g Oeste 20 0 Norte 1er 3er le g a c y   d a ta   s o u rc e s trim. re gtrim. s e n s o r  n e tw o rk s is trie sEnabling Ontology-based Access to Streaming Data Sources 25
    • Implementation • Design, implement and deploy a Semantic Integration Service • Extend existing ontology- based data integration models to take into account sensor networks streaming data, semantic heterogeneity and quality of serviceEnabling Ontology-based Access to Streaming Data Sources 26
    • Implementation S2O mappings repository Translator IntegrationInterface IntegrationCCO- SNEE QueryInterface Query Service Client WS -WS SNEEql PullInterface IntegrateAs (DataResourceAddressList, S2O document) DataResourceAddress SPARQLQueryFactory (DataResourceName, SPARQLSTR ) addQuery DataResourceAddress GetStreamNewestItem(DataResourceName ) repeat getResultSet DataSetEnabling Ontology-based Access to Streaming Data Sources 27
    • Implementation • Flood Warning Application - Wave Height updated every 10 min - Live data from sensor in buoys - Over 30 deploymentsEnabling Ontology-based Access to Streaming Data Sources 28
    • Conclusions Ontology-base data access • Define stream extensions for R2O • Define SPARQLStream language syntax and semantics • Define S2O mappings-based translation semantics Implementation • Enable engine support for « S2O » documents, SPARQLStream queries • Enabled engine support for SNEEql translation and connection • Limited to non-distributed scenario initiallyEnabling Ontology-based Access to Streaming Data Sources 29
    • Future Work • Ontology-based data access • SPARQL construct expressions, aggregates, projected operators • Implement adapters for other streaming sources • Add query rewriting algorithms • Ontology-based streaming data integration • Horizontal & vertical integration • Integrate streaming + stored data • RDF data sources integration • Streaming query optimization • Analyze cost models • Streaming sources statistics and metadata • Quantitative evaluationEnabling Ontology-based Access to Streaming Data Sources 30
    • Planet Data • EU FP7 Network of Excellence • Working with EPFL Global Sensor Network • SwissExperiment DataEnabling Ontology-based Access to Streaming Data Sources 31
    • Co-authors of this work • Oscar Corcho – Universidad Politécnica de Madrid • Alasdair Gray – The University of Manchester • Supported by the SemSorGrid4Env FP7-223913Enabling Ontology-based Access to Streaming Data Sources 32
    • Thanks! Ontology-based Access to Streaming Data Sources Jean-Paul Calbimonte jp.calbimonte@upm.esEnabling Ontology-based Access to Streaming Data Sources 33