sensors, mappings and queries in the semantic web

Date: 06/07/2011

Sensors, Mappings and Queries(from a Semantic Web perspective)

Jean-Paul CalbimonteOntology Engineering Group.

Facultad de Informática, Universidad Politécnica de Madrid.

[email protected]

OEG – Charlas de Grupo

Outline

2Sensors, Mappings and Queries

• Previous work• Sensor data• Sensor metadata• Semantic Web representation• Mapping sensor streams• Query observations• Data integration

Previously on …


• Work with Flood environmental sensor data.• SemSorGrid4Env project www.semsorgrid4env.eu.

We are getting high waves

around here!

Live sensor data

Continuous queries

http://www.semsorgrid4env.eu/

Previously on…


SELECT ?waveheightFROM STREAM <www.ssg4env.eu/SensorReadings.srdf> [FROM NOW -10 MINUTES TO NOW STEP 1 MINUTE]WHERE { ?WaveObs a sea:WaveHeightObservation; sea:hasValue ?waveheight; }

Query translation

Query ProcessingC

lient

Stream-to-Ontology mappings

SPARQLStream

[tuples]

Sensor Network

Data translation[triples]

SNEEql

conceptmap-def WaveHeightMeasurement virtualStream <http://ssg4env.eu/Readings.srdf> uri-as concat('ssg4env:WaveSM_', wavesamples.sensorid,wavesamples.ts) attributemap-def hasValue operation constant has-column wavesamples.measured dbrelationmap-def isProducedBy toConcept Sensor joins-via condition equals has-column sensors.sensorid has-column wavesamples.sensorid

conceptmap-def Sensor uri-as concat('ssg4env:Sensor_',sensors.sensorid) attributemap-def hasSensorid operation constant has-column sensors.sensorid

S2O Mappings

SELECT measured FROM wavesamples [NOW -10 MIN]

Previously on …


• Mapping data streams to ontologies

• Use ontological schemas to write queries over streaming data sources

• Rewriting SPARQL-Stream queries into declarative stream queries (e.g. SNEEql)

s:windsamples

sensorid: int PKts: datetime PKspeed: float

t:sensors

sensorid: int PKsensorname: st

WindSpeedMeasurement

Sensor

isProducedBy

xsd:int

hasSpeed

conceptmap-def WindSpeedMeasurement virtualStream <http://ssg4env.eu/Readings.srdf> uri-as concat('ssg4env:WindSM_', windsamples.sensorid,windsamples.ts) attributemap-def hasSpeed operation constant has-column windsamples.speed dbrelationmap-def isProducedBy toConcept Sensor joins-via condition equals has-column sensors.sensorid has-column windsamples.sensorid

conceptmap-def Sensor uri-as concat('ssg4env:Sensor_',sensors.sensorid) attributemap-def hasSensorid operation constant has-column sensors.sensorid

xsd:float

hasSensorid

OntologiesStreams S2O Mapping

Calbimonte, J-P., Corcho O., Gray, A. Enabling Ontology-based Access to Streaming Data Sources. In ISWC 2010.

Keep on working

• Other streaming technologies?

• Other query languages?

• Hundreds of sensors?

• Integrating heterogeneous data?


Beyond SSG4Env Streaming Data Services

Other than SNEEql: CQL-like, Service calls

Not only toy-like streams

Many sources from different providers, schemas

A little help from our friends

• FP7 Network of Excellence

• Swiss Experiment


GeoResearcher

Environmental and GeoScience researchSwiss Alps

...

...

...

Real-time data

Snow,Wind,Radiation.Lot of stuff

I want data to create my pretty

models and compare

I want to win a best paper

award

SwissEx


• Global Sensor Networks, deployment for SwissEx.

• Distributed environment: GSN Davos, GSN Zurich, etc.• In each site, a number of sensors available• Each one with different schema

• Metadata stored in wiki• Federated metadata management:• Jeung H., Sarni, S., Paparrizos, I., Sathe, S., Aberer, K., Dawes, N., Papaioannus, T.,

Lehning, M.Effective Metadata Management in federated Sensor Networks. in SUTC, 2010

Sensor observations

Sensor metadata

Sensor Metadata


station

location

model

sensors

properties

Sensor Metadata

• What properties are measured

• Which sensors available

• Where are they located

• How are they configured

• Who is responsible


Sensor Data: Observations


Heterogeneity

Integration

A model to bind them all

• W3C SSN Ontology


ssn:FeatureOfInterest

ssn:Observation

ssn:isProducedByssn:SensorOutput

ssn:Sensor

ssn:featureOfInterest

ssn:ObservationValue

ssn:Property

ssn:observedByssn:observationResult ssn:hasValue

ssn:hasProperty

ssn:observedProperty

ssn:observes

xsd:datatype

quantityValue

SSN Ontology


ssn:OperatingRange

ssn:SensingDevice

ssn:hasOperatingRange

ssn:Device

ssn:Sensor

ssn:MeasurementCapability

ssn:Sensing

ssn:System

ssn:Deployment

ssn:Platform

ssn:hasDeployment

ssn:deployedOnPlatformssn:implements

ssn:hasMeasurementCapability

ssn:onPlatform

So Far


qQuery

translation

q’Query

Processing

Data translation

dd’

Clie

nt

mappings

[tuple][tuple]

[triple]

Ontology-based sensor query service

SPARQLStream

Target query Se

nso

r Ne

two

rks

SSN Onto

logy

???

Creating Mappings


wan7

timed: datetime PKsp_wind: float

ssn:ObservationValue

qudt:numericValue

xsd:decimal

http://swissex.ch/data#Wan7/WindSpeed/ObsValue{timed}

sp_wind

ssn:SensorOutput

ssn:Observation

ssn:hasValue

ssn:observationResulthttp://swissex.ch/data#

Wan7/WindSpeed/Observation{timed}

http://swissex.ch/data#Wan7/ WindSpeed/ ObsOutput{timed}

ssn:Property

ssn:observedProperty

sweetSpeed:WindSpeed

R2RML

• RDB2RDF W3C Group, R2RML Mapping language:• http://www.w3.org/2001/sw/rdb2rdf/r2rml/


:Wan4WindSpeed a rr:TriplesMapClass; rr:tableName "wan7"; rr:subjectMap [ rr:template "http://swissex.ch/ns#WindSpeed/Wan7/{timed}"; rr:class ssn:ObservationValue; rr:graph ssg:swissexsnow.srdf ]; rr:predicateObjectMap [ rr:predicateMap [ rr:predicate ssn:hasQuantityValue ]; rr:objectMap[ rr:column "sp_wind" ] ]; .

<http://swissex.ch/ns#/WindSpeed/Wan7/2011-05-20:20:00 > a ssn:ObservationValue<http://swissex.ch/ns#/WindSpeed/Wan7/2011-05-20:20:00 > ssn:hasQuantityValue " 4.5"

http://www.w3.org/2001/sw/rdb2rdf/r2rml/



So Far


qQuery

translation

q’Query

Processing

Data translation

dd’

Clie

nt

mappings

[tuple][tuple]

[triple]

Ontology-based sensor query service

SPARQLStream

Target query Se

nso

r Ne

two

rks

SSN Onto

logy

R2RM

L

GSN

???

Data Access

• GSN Web Services• GSN URL API

• Compose the query as a URL:


http://montblanc.slf.ch :22001/ multidata ?vs [0]= wan7 &field [0]= sp_wind &from =15/05/2011+05:00:00& to =15/05/2011+10:00:00&c_vs [0]= wan7 & c_field [0]= sp_wind & c_min [0]=10

SELECT sp_wind FROM wan7 [NOW -5 HOUR] WHERE sp_wind >10 ?

Algebra expressions


timed,sp_wind

π

ω

σ sp_wind>10

5 Hour

wan7

http://montblanc.slf.ch :22001/ multidata ?vs [0]= wan7 &field [0]= sp_wind &from =15/05/2011+05:00:00& to =15/05/2011+10:00:00&c_vs [0]= wan7 & c_field [0]= sp_wind & c_min [0]=10

SELECT sp_wind FROM wan7 [NOW -5 HOUR] WHERE sp_wind >10

Algebra construction


timed,sp_wind

π

ω

σ sp_wind>10

5 Hour

wan7

windsensor1

windsensor2

Static optimization


timed,sp_wind

π

ω

σ sp_wind>10

5 Hour

wan7

timed,windvalue

π

ω

σ windvalue>10

5 Hour

windsensor1

timed,windvalue

π

ω

σ windvalue>10

5 Hour

windsensor2

Getting things done

• Transformed wiki metadata to SSN instances in RDF• Generated R2RML mappings for all sensors• Implementation of Ontology-based querying over

GSN• Fronting GSN with SPARQL-Stream queries• Numbers:

• 28 Deployments• Aprox. 50 sensors in each deployment• More than 1500 sensors• Live updates. Low frequency• Access to all metadata/not all data


Ugly little demo

• Problems• Too many sensors• Too Heterogeneous

• Any sensors available in this region?• Sensors that measure wind speed?• How about getting the data?


Playing with it


Conclusions

• Thou shalt use the SSN Ontology !• Using R2RML mappings• We can apply the approach to different technologies• We can translate to query languages and APIs• Algebra expressions are cool• Scale to hundreds of sensors


TODO

• Make things usable• Combine with LD generation• Integrate with stored RDF data• Streaming/Dynamic RDF vocabularies• Apply to other environments

• MonetDB• OGC SOS Services• Pachube


Thanks!

• Questions, please.


sensors, mappings and queries in the semantic web

Education

column sensors

sensor uri

sensor datacontinuousquerieswe

hundreds of sensors

streaming data sources

isproducedby toconcept

integratingheterogeneous

time data