Client-sideProcessingofGeoSPARQLFunc9onswithTriplePa?ernFragmentsChristopheDebruyne(TrinityCollegeDublin)ÉamonnClinton(OrdnanceSurveyIreland)DeclanO’Sullivan(TrinityCollegeDublin)2017-04-03@LinkedDataontheWeb(LDOW2017)

TheADAPTCentreisfundedundertheSFIResearchCentresProgramme(Grant13/RC/2106)andisco-fundedundertheEuropeanRegionalDevelopmentFund.

www.adaptcentre.ie Introduc9on

Geospa9alinforma9onisanimportantpartoftheLDWebSomegeographicLDdatasetsareauthorita9ve•  OrdnanceSurveyLinkedData(UK),data.geohive.ie(IE)

NotallgeographicLDdatasetsadoptstandards•  OrdnanceSurveyLinkedDatausestheirownvocabulary,and

providesnosupportforspaXalfuncXonsNotallendpointsservingGeoSPARQLsupportitsfunc9ons•  GeospaXalfuncXonsarecomputaXonalexpensive;serverload•  Oneo[enprovidesdatadumpsandresolvableURIsasa“good

enough”pracXcetoavoidthisproblem(Verborghetal.2016)

R.Verborgh,M.VanderSande,O.HarXg,J.VanHerwegen,L.DeVocht,B.DeMeester,G.Haesendonck,andP.Colpaert.2016.TriplePacernFragments:Alow-costknowledgegraphinterfacefortheWeb.J.WebSem.37-38(2016),184–206

www.adaptcentre.ie Introduc9on–data.geohive.ie

data.geohive.ieisanongoingcollaboraXonbetweenADAPTandtheOrdnanceSurveyIrelandtopublishOSi’sauthoritaXvegeospaXalinformaXonasLinkedData.StarXngfrompubliclyavailableboundarydata,supporXngtwousecases:provisionofdifferentgeometriesforfeatures,andprovenanceandevoluXonoffeaturesandtheirgeometries

www.adaptcentre.ie Introduc9on–data.geohive.ie

data.geohive.ie•  ProvidesresolvableURIs,dumpsandaLDfrontend•  DecidedagainstprovidingapublicSPARQLendpoint•  TriplePacernFragmentswereadoptedinstead

TriplePa?ernFragments(TPF)•  DistributeloadbetweenaTPFclientandserver•  Lessloadontheserveratthecostofincreasedbandwidth

www.adaptcentre.ie Introduc9on–data.geohive.ie

But,TPFhasnosupportforGeoSPARQL•  Non-implementaXonratherthanlimitaXon•  GeoSPARQLisanextensionofSPARQL(scope)

AgentscannotapplyGeoSPARQLfunc9onsonOSi’sauthoritaXvegeospaXalLinkedData,ortheyhavetoloadthedatainGeoSPARQL-enabledtriplestoresWoulditbefeasibletoextendTPFwithGeoSPARQL?FeasibleasinaviableapproachtoprocessGeoSPARQL

www.adaptcentre.ie Approach

Twopossibleapproaches:A)ExtendingaTPFClient•  TPFserverspecificaXonintact(backwardscompaXble)•  PossiblymorenetworkoverheadB)ExtendingtheTPFserver•  OutsideserverspecificaXon,butproventobeviablefor

substringfiltering(VanHerwegenetal.2015)

Addi9onalrequirement:apureJavaScriptimplementa9on•  Allowsonetoruntheclientinabrowserandhencefacilitate

stakeholdersinformulaXngGeoSPARQLqueries

J.VanHerwegen,L.DeVocht,R.Verborgh,E.Mannens,andR.VandeWalle.2015.SubstringFilteringforLow-CostLinkedDataInterfaces.InTheSemanXcWeb-ISWC2015-14thInternaXonalSemanXcWebConference,Bethlehem,PA,USA,October11-15,2015,Proceedings,PartI(LNCS),Vol.9366.Springer,128–143.

www.adaptcentre.ie Approach

Implementa9on•  WeextendedV2.0.4oftheTPFNode.jsClient

(Availableathcps://github.com/chrdebru/Client.js)•  Madeavailableaweb-clientusingthisextension

(Athcp://theme-e.adaptcentre.ie/geo-tpf/)GeoSPARQLcoverage•  SupportforGeoSPARQLFILTERfuncXonsthatwedeemtooccur

o[eninexamples(sfTouches,sfWithin,…)Func9onsareimplementedintermsofsetopera9ons•  E.g.,sfOverlaps:TheintersecXonofthe2geometriesisnot

emptyandshouldcontainpolygonsormulX-polygonsdenoXngareas.

www.adaptcentre.ie Demonstra9on

PaperprovidesdetailsonusewithinthecontextofaTCDLibraryLinkedDataandSensorDataanalysisprojects.

www.adaptcentre.ie Discussion(condensed)

Onperformance•  BasedoniniXalexperiments.MostXmewenttoprocessingofGeoSPARQL

FILTERfuncXons.SlightlyworseresultsintermsofXmecomparedtorunningqueriesinatriplestore.Wethusdeemourapproachviable.

•  However,ourapproachusingJavaScript(inabrowser)willunlikelyoutperformsuchtriplestoresintermsofperformance

OnOp9miza9on•  OSiprovideshigh-respolygons,whichcausesalotofnetworktraffic.•  br-TPF(HarXgandBuilAranda,2016)didreducethenumberofHTTPcalls,

butnotreallytheamountoftrafficforthepolygons.•  Server-sidesupportforGeoSPARQLfuncXonscouldtacklethatproblem

O.HarXgandC.BuilAranda.2016.Bindings-RestrictedTriplePacernFragments.InOntheMovetoMeaningfulInternetSystems:OTM2016Conferences-ConfederatedInternaXonalConferences:CoopIS,C&TC,andODBASE2016,Rhodes,Greece,October24-28,2016,Proceedings(LNCS),Vol.10033.Springer,762–779.

www.adaptcentre.ie ConclusionsandFutureWork

Conclusions•  WeextendedaTPFclienttosupportGeoSPARQLfuncXons•  Thepaperillustrateshowweuseditfordifferentprojects

LessonsLearned•  IniXalresultsshowedourapproachisviable•  ThoughnetworkoverheadmaysXllbeanissue,anextensionoftheTPF

serverisworthwhileexploring(futurework)•  HowtodealwithGeoSPARQLpredicatesandfuncXons?

Futurework•  CompleteimplementaXonandtestwithfuncXonalbenchmarks,e.g.,

Geographica(Garbisetal,2013)•  Experimentsinvolvingstakeholders,andidenXfythelimitaXonsofour

approachtocharacterize,forinstance,“sensible”queries

G.Garbis,K.Kyzirakos,andM.Koubarakis.2013.Geographica:ABenchmarkforGeospaXalRDFStores(LongVersion).IntheSemanXcWeb-ISWC2013-12thInternaXonalSemanXcWebConference,Sydney,NSW,Australia,October21-25,2013,Proceedings,PartII(LNCS),Vol.8219.Springer,343–359.