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Ingredients for Semantic Sensor Networks
1. Ingredients for the Semantic Sensor Web Jožef Stefan Institute Ljubljana, Slovenia September 23rd 2011 Oscar Corcho Facultad de Informática,Universidad Politécnica de Madrid Campus de Montegancedosn, 28660 Boadilla del Monte, Madrid http://www.oeg-upm.net ocorcho@fi.upm.es Phone: 34.91.3366605 Fax: 34.91.3524819
2. Index PART I. Motivation From Sensor Networks… … to the Sensor Web / Internet of Things… … to Semantic Sensor Web and Linked Stream/Sensor Data
19. The Sensor Web (relatedto Internet of Things) Universal, web-based access to sensor data Some sensor networkproperties: Networked Mostlywireless Each network with some kind of authority and administration Sometimes noisy 9 Source: Adaptedfrom Alan Smeaton’sinvitedtalk at ESWC2009
20. Should we care as computer scientists? They are mostly useful for environmental scientists, physicists, geographers, seismologists, … [continue for more than 100 disciplines] Hence interesting for those computer scientists interested on helping these users… We are many ;-) But they are also interesting for “pure” computer scientists They address an important set of “grand challenge” Computer Science issues including: Heterogeneity Scale Scalability Autonomic behaviour Persistence, evolution Deployment challenges Mobility Source: Dave de Roure
21. A semanticperspectiveonthesechallenges Sensor data querying and (pre-)processing Data heterogeneity Data quality New inferencecapabilitiesrequiredtodealwith sensor information Sensor data modelrepresentation and management For data publication, integration and discovery Bridgingbetween sensor data and ontologicalrepresentationsfor data integration Ontologies: Observations and measurements, time series, etc. Eventmodels Userinteractionwith sensor data
22. Vision (aftersomeiterations, and more to come) 12 RWI WorkingGrouponIoT: NetworkedKnowledgeGluhak et al, 2011. AnArchitecturalBlueprintfor a Real-World Internet', FutureInternet Assembly
23. Semantic Sensor Web / LinkedStream-Sensor Data (LSD) A representation of sensor/streamdata followingthestandards of LinkedData ButwhatisLinked Data?
24.
25. … where data are given well-defined and explicitly represented meaning, …
26. … so that it can be shared and used by humans and machines, ...
29. Semantic Sensor Web / LinkedStream-Sensor Data (LSD) A representation of sensor/streamdata followingthestandards of LinkedData Addingsemanticsallowsthesearch and exploration of sensor data withoutany prior knowledge of the data source Usingtheprinciples of Linked Data facilitatestheintegration of stream data totheincreasingnumber of Linked Data collections Earlyreferences… AmitSheth, CoryHenson, and SatyaSahoo, "Semantic Sensor Web," IEEE Internet Computing, July/August 2008, p. 78-83 Sequeda J, Corcho O. LinkedStream Data: A Position Paper. Proceedingsof the 2nd International WorkshoponSemantic Sensor Networks, SSN 09 Le-Phuoc D, Parreira JX, Hauswirth M. Challengesin LinkedStream Data Processing: A Position Paper. Proceedingsof the3rd International WorkshoponSemantic Sensor Networks, SSN 10
30. Let’schecksomeexamples Meteorological data in Spain: automaticweatherstations http://aemet.linkeddata.es/ Paperunder open review at theSemantic Web Journal http://www.semantic-web-journal.net/content/transforming-meteorological-data-linked-data Live sensors in Slovenia http://sensors.ijs.si/ ChannelCoastalObservatory in Southern UK http://webgis1.geodata.soton.ac.uk/flood.html And some more from DERI Galway, Knoesis, CSIRO, etc. 17
33. Coastal Channel Observatory and other sources 20 Sensors, Mappings and Queries Work with Flood environmental sensor data. SemSorGrid4Env project www.semsorgrid4env.eu.
34. PART II How to create, publish and consume Linked Stream Data
35. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
36.
37. State of the art on sensor network ontologies in the report below
38. In 2009, a W3C incubator group was started, which has just finished
44. SSN Ontology paper submitted to Journal of Web SemanticsSSN ontologies. History
45. Deployment System OperatingRestriction Process Device PlatformSite Data Skeleton ConstraintBlock MeasuringCapability Overview of the SSN ontology modules
46. deploymentProcesPart only Deployment System OperatingRestriction hasSubsystem only, some hasSurvivalRange only SurvivalRange DeploymentRelatedProcess hasDeployment only System OperatingRange Deployment hasOperatingRange only deployedSystem only deployedOnPlatform only Process hasInput only inDeployment only Device Input Device Process onPlatform only PlatformSite Output Platform hasOutput only, some attachedSystem only Data Skeleton implements some isProducedBy some Sensor Sensing hasValue some SensorOutput sensingMethodUsed only detects only SensingDevice observes only SensorInput ObservationValue isProxyFor only Property isPropertyOf some includesEvent some observedProperty only observationResult only hasProperty only, some observedBy only Observation FeatureOfInterest featureOfInterest only ConstraintBlock MeasuringCapability hasMeasurementCapability only forProperty only inCondition only inCondition only Condition MeasurementCapability Overview of the SSN ontologies
47. SSN Ontology. Sensor and environmental properties Skeleton Property Communication MeasuringCapability hasMeasurementProperty only MeasurementCapability MeasurementProperty Accuracy Frequency Precision Resolution Selectivity Latency DetectionLimit Drift MeasurementRange ResponseTime Sensitivity EnergyRestriction OperatingRestriction hasOperatingProperty only OperatingProperty OperatingRange EnvironmentalOperatingProperty MaintenanceSchedule OperatingPowerRange hasSurvivalProperty only SurvivalRange SurvivalProperty EnvironmentalSurvivalProperty SystemLifetime BatteryLifetime
48. A usageexample Upper SWEET DOLCE UltraLite SSG4Env infrastructure SSN Schema Service External OrdnanceSurvey FOAF Flood domain CoastalDefences AdditionalRegions Role 27
50. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
52. Goodpractices in URI Definition Wehavetoidentify… Sensors Features of interest Properties Observations Debate betweenbeingobservationor sensor-centric Observation-centricseemsto be thewinner Forsomedetails of sensor-centric, check [Sequeda and Corcho, 2009]
53. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
54. Queries to Sensor/Stream Data SNEEql RSTREAM SELECT id, speed, direction FROM wind[NOW]; Streaming SPARQL PREFIX fire: <http://www.semsorgrid4env.eu/ontologies/fireDetection#> SELECT ?sensor ?speed ?direction FROM STREAM <http://…/SensorReadings.rdf> WINDOW RANGE 1 MS SLIDE 1 MS WHERE { ?sensor a fire:WindSensor; fire:hasMeasurements ?WindSpeed, ?WindDirection. ?WindSpeed a fire:WindSpeedMeasurement; fire:hasSpeedValue ?speed; fire:hasTimestampValue ?wsTime. ?WindDirection a fire:WindDirectionMeasurement; fire:hasDirectionValue ?direction; fire:hasTimestampValue ?dirTime. FILTER (?wsTime == ?dirTime) } C-SPARQL REGISTER QUERY WindSpeedAndDirection AS PREFIX fire: <http://www.semsorgrid4env.eu/ontologies/fireDetection#> SELECT ?sensor ?speed ?direction FROM STREAM <http://…/SensorReadings.rdf> [RANGE 1 MSEC SLIDE 1 MSEC] WHERE { … 33 Semantically Integrating Streaming and Stored Data
55. SPARQL-STR v1 34 Sensors, Mappings and Queries SELECT ?waveheight FROM STREAM <www.ssg4env.eu/SensorReadings.srdf> [FROM NOW -10 MINUTES TO NOW STEP 1 MINUTE] WHERE { ?WaveObs a sea:WaveHeightObservation; sea:hasValue ?waveheight; } SELECT measuredFROM wavesamples [NOW -10 MIN] conceptmap-def WaveHeightMeasurement virtualStream <http://ssg4env.eu/Readings.srdf> uri-as concat('ssg4env:WaveSM_', wavesamples.sensorid,wavesamples.ts) attributemap-defhasValue operation constant has-columnwavesamples.measured dbrelationmap-def isProducedBy toConcept Sensor joins-via condition equals has-column sensors.sensorid has-columnwavesamples.sensorid conceptmap-def Sensor uri-as concat('ssg4env:Sensor_',sensors.sensorid) attributemap-def hasSensorid operation constant has-column sensors.sensorid Query translation SNEEql SPARQLStream Query Processing Stream-to-Ontology mappings Client Sensor Network Data translation [tuples] [triples] S2O Mappings Source: EnablingOntology-based Access toStreaming Data Sources. Calbimonte JP, Corcho O, Gray AJG. ISWC 2010
56. SPARQL-STR v2 SPARQLStream algebra(S1 S2 Sm) GSN Query translation q SNEEql, GSN API Sensor Network (S1) SPARQLStream (Og) Relational DB (S2) Query Evaluator Stream-to-Ontology Mappings (R2RML) Client Stream Engine (S3) RDF Store (Sm) Data translation [tuples] [triples] Ontology-based Streaming Data Access Service Source: PlanetDatadeliverable D1.1 (to be published in Sep 30th 2011) www.planetdata.eu
64. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
65.
66. Temporal/spatial data are represented by linear constraints, representing as literals of type strdf:semiLinearPointSet.
68. Querying: stSPARQL Find all WMS services with FOI flood plain that cover the Coastal Defence Partnership modelled area and provide valid information for the next 12 hours select distinct ?ENDPOINT where { ?SERVICE rdf:typeServices:WebService . ?SERVICE Services:hasEndpointReference ?ENDPOINT . ?SERVICE Services:hasServiceTypeServices:WMS . ?SERVICE Services:hasDataset ?DATASET . ?DATASET Services:includesFeatureTypeCoastalDefences:FloodPlain. ?DATASET time:hasTemporalExtent ?TIME . filter(?TIME contains “[NOW,NOW+12]"^^RegistryOntology:TemporalInterval) . ?DATASET Services:coversRegion ?SERVICEREGION . ?SERVICEREGION Services:hasSpatialExtent ?SERVICEREGIONGEO . AdditionalRegions:CoastalDefencePartnershipModelledArea Services:hasSpatialExtent ?COSTALGEO . filter(?SERVICEREGIONGEO contains ?COSTALGEO) } Source: Our NKUA partners at SemsorGrid4Env 2nd Year Review Meeting - Brussels, 16-17 Nov. 2010 44
69. Implementation: STRABON SupportforstRDF and SPARQL, plus Topologicaloperators in spatialfilters DISJOINT, TOUCH, EQUALS, CONTAINS, COVERS, COVERED BY, OVERLAP ConstructSpatialGeometries e.g. ?geo1 union ?geo2 Projectionoperation e.g. ?geo[1,2] Renameoperator ConversionFunctionsforexportinggeometries: e.g. ToWKT(?geo) AS ?geoAsWKT Library thatreturns SPARQL results as a KML document 45 Source: Our NKUA partners at SemsorGrid4Env
70. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
71. Sensor High-level API Source: Kevin Page and rest of Southampton’steam at SemsorGrid4Env
72. Sensor High-level API Source: Kevin Page and rest of Southampton’steam at SemsorGrid4Env
74. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
75. SwissEx 51 Sensors, Mappings and Queries Global Sensor Networks, deployment for SwissEx. Distributedenvironment: GSN Davos, GSN Zurich, etc. In each site, a number of sensorsavailable Each one withdifferentschema Metadatastored in wiki Federatedmetadata management: Jeung H., Sarni, S., Paparrizos, I., Sathe, S., Aberer, K., Dawes, N., Papaioannus, T., Lehning, M.EffectiveMetadata Management in federatedSensor Networks. in SUTC, 2010 Sensor observations Sensormetadata
76. Gettingthingsdone Transformed wiki metadata to SSN instances in RDF Generated R2RML mappings for all sensors Implementation of Ontology-basedquerying over GSN Fronting GSN with SPARQL-Stream queries Numbers: 28 Deployments Aprox. 50 sensors in eachdeployment More than 1500 sensors Live updates. Lowfrequency Access to all metadata/not all data 52 Sensors, Mappings and Queries
80. HowtodealwithLinkedStream/Sensor Data Ingredients Anontologymodel Goodpractices in URI definition Supportingsemantictechnology SPARQL extensions Tohandle time and tuplewindows Tohandlespatio-temporal constraints REST APIstoaccessit Anotherexample: semanticallyenriching GSN A couple of lessonslearned
81. LessonsLearned High-level (part I) Sensor data isyetanothergoodsource of data withsomespecialproperties Everythingthatwe do withourrelationaldatasetsorother data sources can be done with sensor data Practicallessonslearned (part II) Manageseparatelydata and metadata of thesensors Data shouldalways be separatedbetweenrealtime-data and historical-data Use the time formatxsd:dateTimeand the time zone Graphicalrepresentation of data forweeksormonthsisnot trivial anyway
82. Ingredients for the Semantic Sensor Web Jožef Stefan Institute Ljubljana, Slovenia September 23rd 2011 Oscar Corcho Acknowledgments: allthoseidentified in slides + the SemsorGrid4Env team (Jean Paul Calbimonte, Alasdair Gray, Kevin Page, etc.), the AEMET team at OEG-UPM (GhislainAtemezing, Daniel Garijo, José Mora, María Poveda, Daniel Vila, Boris Villazón) + Pablo Rozas (AEMET)
Notas del editor
The where clasue for both SPARQL extensions is the same