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OSGeoJournalVolume10
Volume 10 Contents UsingGRASSandRforLandscapeRegionaliza-
tionthroughPAMClusterAnalysis . . . . . . 26
FunctionalCoverages . . . . . . . . . . . . . . . . 32
FOSS4G2011ConferenceProceedings 2 OpticksOpenSourceRemoteSensingandImage
Editorial-FOSS4G2011AcademicChair . . . . 3 ProcessingSoftware . . . . . . . . . . . . . . . 44
Opensourcebasedonlinemapsharingtosupport Implementation,challengesandfuturedirections
real-timecollaboration . . . . . . . . . . . . . . 5 ofintegratingservicesfromtheGISanddeci-
AninnovativeWebProcessingServicesbasedGIS sionsciencedomains . . . . . . . . . . . . . . . 49
architecture . . . . . . . . . . . . . . . . . . . . 15 AVividRelicUnderRapidTransformation . . . 55
Welcome from the Conference Chair
WelcometothisspecialeditionoftheOSGeoJournal,featuringselectedpapersfromthe
academictrackthatwerepresentedattheFOSS4G(FreeandOpenSourceSoftwarefor
Geospatial)2011conferenceinDenver.1 TheconferencewasthelargestFOSS4Gyet,with
914attendeesfrom42countries. Feedbackfromattendeeswasverypositive,withthe
post-conferencesurveygivingitanoverallratingof4.32out5. Theattendancereflects
thestronggrowthininterestinopensourcesoftwarethatwearecurrentlyseeinginthe
geospatialindustry.
Wemadeaconsciouseffortin2011toenhancetheacademictrackattheconference
byprovidingimprovedpublishingopportunities. Wedidthisthroughpublishingpapers
bothin“TransactionsinGIS”andinthiseditionoftheOSGeoJournal. Iwouldliketo
thankRafaelMorenoforleadingthiseffort,aswellastherestoftheorganizersofthe
academictrackwhoRafaelrecognizesbelow.
PeterBatty,Ubisense
FOSS4G2011ConferenceChair
1FOSS4G:http://foss4g.org
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OSGeoJournalVolume10 FOSS4G2011ConferenceProceedings
FOSS4G 2011 Conference Proceedings
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OSGeoJournalVolume10 Implementation,challengesandfuturedirectionsofintegratingservicesfromthe...
Implementation, challenges and future
directions of integrating services from the
GIS and decision science domains
AcaseofDistributedSpatialMulti-CriteriaEvaluation environmentalmanagement(Zuccaetal.,2008)inpoverty
assessment(ODPM,2004,Baudetal.,2009). Itisalsoused
LucBoerboom inparticipatorydecisionprocesseseithernormativelymoti-
FacultyofGeo-InformationScienceandEarthObservation(ITC) vatedbecauseitshouldmakedecisionsmoredemocratic,or
UniversityofTwente,P.O.Box217,7500AEEnschede,TheNether- rationallymotivatedbecauseitshouldmakedecisionsmore
lands,[email protected] informed,orinstrumentallybecauseitshouldmakedecision
ÖzgünOskayAlan responsibilityforpossiblefailuresshared(Stirling,2006).The
FacultyofGeo-InformationScienceandEarthObservation(ITC) number of publications has experienced a strong increase
UniversityofTwente,[email protected] (Malczewski,2006).
Butonthewebitcouldaidandchangeindividualand
collaborativedecisionmaking.Itcouldcreateneedandop-
Abstract
portunityforexpandingtherangeofmethodsfortheanalysis
ofspatialpreferenceofgroupsofpeople,forcollaborative
Weareimplementinganopensourceprojectforspatialdeci-
analysis of conflict and consensus, and for learning about
sionmakingcalledDistributedSpatialMulti-CriteriaEvalua-
decision making and decision making processes. It could
tion(DSMCE)underanEUprojectforinter-regionaldevelop-
addvaluetoandbetweenspatialdatainfrastructures,and
mentonforestryandclimatechangeadaptation(ForeStClim).
performintegratedassessmentbetweenorganizationalman-
Inthispaper,wefirstdescribewhatDSMCEisandwhat
dates.Anditcouldgetinfrastructuralproperties(Boerboom,
itdoes. Wehavedesignedanextensiblearchitectureforin-
2010).
tegratingservicesoftwodomains,respectivelytheGISand
SofartherehasonlybeenoneimplementationofSMCE
DecisionSciencesdomain.Therebywedelegatedomainex-
that is server-based with the lightness of a browser client,
pertise to available implementations. We use the Service
whichisParticipatoryGIS.com(BoroushakiandMalcewski,
OrientedArchitecture(SOA)paradigmtobuildourDSMCE
2010),butunlikeourimplementationithasnotbeenimple-
serviceandapplication. Integrationisimplementedbythe
mentedasagenerictoolbutforaspecificprojectnordoes
useofopenspecificationsandprotocolscomingfromthese
makeuseofOGCwebservicesstandardsandimplementa-
domains. DSMCEisnotonlyextensibleintermsoftheex-
tions.
ternalservicesituses,italsoisextensibleasanapplication
Wepresentthefirstprototypeimplementationoftheopen
because it is developed with OSGi technology which that
sourcedistributedspatialmulti-criteriaevaluation(DSMCE)
bringsadvancedmodularity.
web application. It is distributed, not only in the concept
Secondweshareobservationsaboutimplementationchal-
ofdistributedcomputing, becauseitcancollectdatafrom
lengeswehaveaddressed.Thesechallengesarerelatedtothe
distributeddatasources,i.e.WebFeatureServices(WFS),or,
designofintegrationofthetwodomains,theabilityofspeci-
ifdatacannotbeexchangedbecauseofdatapolicies, data
ficationstoaddressrealimplementationproblems,andthe
value,bandwidth,andotherreasons,itcanbedistributedto
reliabilityandqualityofavailableopensourcetools.These
thesedatasourcesandcollectonlytheintermediaryoutputs.
leadustoconclusionsaboutthesolutionswehadtoimple-
Also, decisionmakersaregeographicallydistributedorin
ment.
time. Anddevelopmentofitcanbedistributed,giventhe
Third and finally we give an overview of future direc-
opensourcenature,providedgoodprogrammingpractices
tions. Someofthesetopicsrelatetothespatialdomain,e.g.
andsystemsaremaintained. DistributedSMCEisanopen
theuseofWebProcessingServices(WPS)forpreandpost
sourcewebapplicationdevelopmentprojecthostedonthe
processingarounddecisionanalysis,otherstothedecision
sourceforgeKenai.39
sciencesdomain,e.g.theintegrationofothernon-spatialdata
ImplementingDSMCEwithspatialOGCstandardswas
sourcesandservices,orcollaborativedecisionmaking.
notasstraightforwardastheintendedbyOGC(Percivall,
2010).Wedidnotfindasystematicreviewofissuesaround
Introduction implementationsanduseofOGCstandardsinliterature,al-
though(Heetal.,2009)addressoneoftheissuesusingmulti-
Ifspatialmulti-criteriaevaluation(SMCE)(Herwijnen,1999, versionWFS’.Itisbeyondthescopeofthispapertodoso.
SharifiandRetsios,2004)methodologies,implementations, Butweconsideritusefulforfuturedevelopmentofstandards
andexpertisecouldevolveontheweb,bothdecisionmak- andimplementationstoexplorethechallengeswehavefaced
ingandthedecisionaidingmethodologiescoulddevelopin andthesolutionswehavedeveloped,whichcouldbecome
newdirections.SMCEindesktopapplicationshasbeenused partoffuturemoresystematicstudies.
inanalyticalacademicorconsultingstudiessuchastrans- Sotheoutlineofthispaperisasfollows.Wefirstbriefly
port(SharifiandBoerboom, 2006, Keshkamatetal., 2009), describetheparticularusecaseforwhichthiswebapplication
39http://kenai.com/projects/distributed-DSMCE
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OSGeoJournalVolume10 Implementation,challengesandfuturedirectionsofintegratingservicesfromthe...
isbeingdevelopedanditsgeneralization.Secondwedescribe Thewebapplication(Figure1)opensinanywebbrowser.
thewebapplication.Thenwediscussimplementationchal- Itinitiallyisasinglescreenwithfourpanels. Spatialmulti-
lengeswithopensourcemodules.Finally,wedescribefuture criteria evaluation takes place in the central panel. Here
directions. objectivesandcriteriacanbestructured,standardizedwith
maximumstandardizationtoa0-1scale,prioritizedwiththe
expectedvaluerankingmethod,andaggregated(Nijkamp,
A specific use case and its generaliza-
1990, Sharifi and Retsios, 2004). The Data panel (left) pro-
tion videsaccesstowebfeatureservices. Fromtheservicethe
userreceivessometechnicalinformationandalistoflayers
offered.Afterselectingalayer,itsattributeswillbelistedas
Thespecificusecaseisthefollowing.MostEuropeanforest
thumbnailmapsandtheirattributenames.Multiplethumb-
organizationshaveincludedclimatechangeintheirstrategy
nailscanbepoppedup(popupwindow)toanimageand
documents.Nowthesestrategicintentionsneedtobetrans-
somekeystatisticsofmean,standarddeviation,minimum
latedtoadaptationplansinthedifferentregions.Thisoccurs
andmaximumvalueinordertoobtainafeelingforthedata.
aspartoftheregularforestmanagementadaptationplanning
Thethumbnailscanbedraggedanddroppedintothemaps
processes.Thereforespatialevaluationofvulnerabilityand
field. Thespatialviewpanel(totheright)isaviewerthat
adaptiveoptionsneedstobeconsideredintheseprocesses.
uses OpenLayers, and shows the transparent output map
IntheForeStClimprojecton“TransnationalForestryMan-
ofwell(green)andpoorly(red)performingareasontopof
agementStrategiesinResponsetoRegionalClimateChange
baselayer.HereitisOpenStreetMap.Clickingononeofthe
Impacts“,withinwhichthedistributedspatialmulti-criteria
polygons,attributenamesandvaluesforthatpolygonwill
evaluationwebapplicationisdeveloped,weintendtocom-
bedisplayedintheSpatialInfopanel(lowerrightcorner).
pare several regions. But rather than applying a uniform
evaluationapproachwerecognizetheregionalvariability.
Sotheproblemisthatevaluationofclimatechangevul-
nerabilitiesandsuitabilityofadaptiveoptionisdistributed.
Therearedifferentforestmanagementorganizationsinthe
differentregionsinNorth-westernEurope. Eachorganiza-
tionworksinitsspecificforestpolicyenvironmentandhas
specificpolicyobjectives. Andtheyallhavedifferentdata,
technicaldataenvironments,anddatapolicies. Tosumma-
rize,decisionsoftheseforeseemanagementorganizationsare
idiosyncraticinonlypartlysharedpolicyandmarketenvi-
ronments,andthereisneithervalueinmakingdatabasesand
datasetsinteroperablenorinsemanticallyharmonizingdata.
Finally,theprojecthopesthatintheexchangeofdifferent
evaluationapproachesthedifferentregionswillgainideas
Figure1:ScreenshotoftheDistributedSpatialMulti-Criteria
to improve their own understanding of vulnerability and
Evaluationwebapplication
adaptiveoptions. Andthatthesecanbecommunicatedto
EuropeanpolicybodiesastheMinisterialConferenceonthe
AsdepictedinFigure2thearchitectureconsistsofthree
ProtectionofForestsinEurope
main components: Spatial Services, Decision Support Ser-
Generalizationsfromthisspecificusecasearethefollow-
vicesandfinallytheD-SMCEservice.SpatialServicesconsist
ing.Asfarasdecisionsareconcerned,DSMCEcanbeused
ofdataservicessuchasWFSanddataprocessingservices
fordecisionswheredatacanbethesamefordifferentdeci-
suchasWPS.Inthedecisionsupportservicecomponentwe
sionmakers,butdecisionmakerscanpartiallyorfullyuse
havetheDecisionDeckasamulti-criteriaaidingservice.D-
differentdataanddatasourcesoninternetorintranet.Also
SMCEitselfisaclientofallthoseexternalservicesandplays
itismeanttocommunicatepreferencestructureonInternet
aroleofamediatorservicetobridgetwodomains(Spatial
fordecisionmakerstolearnfromeachothers’approaches
DomainandDecisionSupportdomain)toperformrequired
toevaluationandintegratedassessment.Oftendatacannot
tasksofaSpatialMultiCriteriaAnalysis.Itisimplementedon
besharedormadeinteroperablebecauseitisjustnotworth
theJavaplatformandusesmodulardesignfollowingOSGi
theeffortsinceuseofdataisinfrequentand/oridiosyncratic,
specifications.
anddoesnotpayofftheeffortofmakingdatabasesinteroper-
IfwelookinsidetheD-SMCEcomponenttherewehave
able.Alsodatacanbetoovaluabletobesharedoroutdated
twoservicesaswell. Wehavethebackendservice. Inthis
datashouldnotbeused. DSMCEsupportsdecisionswith
backendserviceweimplementdataaccessandbusinesslay-
organizationaldatabasesandwithdatainfrastructures(SDIs)
ers. Here we have modules of several client implementa-
butalsoatthefringesofSDIs.
tionstoaccessexternalservicesfordataretrievalanddata
processing.Alsowehavesomeothermodulesforrequired
DSMCE calculationsthatexternalservicescannotoffer.Thenthereis
thefrontendservice.Thisserviceconsistsofthepresentation
FirstwedescribewhatDSMCEdoes. Thenwedescribeits layertogetherwithsomeutilitymodulesthatareneededby
architecture. Finally we list functional and technical inno- thewebapplication(e.g. userprofilemanagement, access
vations. DSMCEconsistsoftwoparts,thewebapplication control). The presentation layer is implemented with the
(frontendservice)andthebackendservice. Vaadinframework.
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OSGeoJournalVolume10 Implementation,challengesandfuturedirectionsofintegratingservicesfromthe...
Ourideaistoclearlyseparatethesetwoservices,backend arerepresentedontheweb(i.e.aswebservices)andbuild
andfrontend,byrunningthemastwoindependentservices. a reliable, extensible infrastructure for the mediation of
Ifanecessityarises,wemayliketoaddanewcomponentto allthesedelegatedservices.Thereforecomparingtoother
thisarchitecturesuchasstatisticsservicebyimplementinga softwaresystemsinthefieldofspatialdecisionmaking,
requiredclientinthebackendservice,asitisdepictedinthe DistributedSMCEcanbepositionedasaframeworkrather
bottomofthefigure. thanatailor-madeapplication.
• UseofOSGitechnology.(fig.2)OSGitechnologyisaspeci-
ficationtocreatemodularapplicationsintheJavaplatform.
ThechoiceofOSGitechnologyforDSMCEhasbeenakey
decision.Itistechnicallyandadministrativelymotivated.
Technically,theextensibilitythatisgainedbytheuseof
WebServicescannotbeutilizedwithoutamodularwebap-
plicationthatmediatesinteractionbetweendifferentkinds
of web services. Possibly more important is the admin-
istrativemotivationofdistributedpartialanalysiswithin
differentorganizationalboundaries.Suchschemerequires
bothmodularityandconvenienttoolsfordistributionof
logical components. Distributed SMCE can follow this
schemebyusingOSGi.
• Contribution of own services. Distributed SMCE is not
onlymediatingwebservices, butalsoperforminginter-
mediatecomputationswhicharenotavailableontheweb
ortoospecifictobestandardizedunderOGC,Decision
Figure2: ArchitectureofDistributedSpatialMulti-Criteria Deckorotherstandards.Forinstanceitextractsrelevant
Evaluation informationfromoneservice,e.g. meta-dataandcertain
descriptive statistics from maps like the maximum and
Thecoreofthisnewweb-applicationisfunctionallyand minimumvalues,andusesthisinformationforotherser-
technologically innovative. Functional innovative aspects vicessuchXMCDAservices. Althoughthecomputation
are: mightbespecificstillitmayhavedemandasamodule
• SMCEontheweb. Spatialdataiscurrentlyshownand orasserviceontheweb.Alsoforthesekindofusecases,
sometimesdownloadableoninternet.Amapcanbelooked OSGitechnologyandthecurrentarchitectureofDSMCE
at one at a time. With DSCME multiple maps can be givesenoughroomandflexibility.
viewed, interpreted, and aggregated to perform spatial • Server side rapid development with Ajax/Vaadin. The
evaluation. client,i.e. UserInterface(fig. 2),isbasedontheVaadin
• IntegrationwithMCDAwebservices.(fig2).Wewillapply ServerSideAjaxUIFramework.LikeallotherAjaxframe-
non-spatialmulti-criteriadecisionanalysiswebservices worksVaadinprovidesrichuserexperience. Vaadinhas
standards(XMCDA)(DecisionDeck,2011)inthespatial someadvantagescomparedtootherframeworksinterms
domain.WeightedsummationMCEisthefirstmethodbut ofRapidApplicationDevelopment. Thisisessentialfor
onceembeddedotherscanbeadded. anopensourceprojectwhere3rdpartydevelopersofDis-
• Spatial data from different locations on internet can be tributed SMCE would like to extend Distributed SMCE
broughttotheweb-application andsoitswebclient.ThechoiceofVaadinhassomeimpor-
• Distributedcalculation.Ifdataprovidersdonotwantdata tantimplications.First,sinceVaadinisaserversideAjax
tobemoved,partsofthebackendoftheDSCMEcanbe framework,ithasafairly‘thin’UserInterfacelayerthat
servedfromdifferentlocationswherepartsofacriteria runsonwebbrowsersoftheendusers. Second,browser
treecanbeanalyzedindifferentweblocationsandresults compatibilityissuesarehandledbyVaadin.Sothedevel-
sharedtoa“central”location. operdoesnothavetoworrywhetherthedevelopedcode
isworkingwithdifferentbrowsers.Third,thebigmajority
Technologicalinnovativeaspectsare:
ofoperations,communicationandsecurityishandledin
• Extensibilityofservices.DSMCEisaserviceorientedplat- theserveronaJavaplatform.ThisfeatureofVaadingives
form that mediates the interaction between spatial and usopportunitytodevelopagooddegreeofmodularityin
non-spatialservicesavailableontheweb. Thisfeatureis combinationwiththemodularityenforcedbyOSGithat
uniquesincethemajorityofdecisionsupportsoftwareare appliestotheJavaplatforms. Finally, sincemostofthe
eitherdesktoporisolatedwebapplications. Thisfeature currentwebapplicationsareheavilybasedonJavascript,it
opensopportunitiesforextensionofthesystem(suchas ishardtomodularizethembyusingspecificationssuchas
addingstatisticalcapabilities,etc.) OSGi,orframeworksdevelopedforimperativeprogram-
• Openstandardsandcommunities.DSMCEusesopenstan- minglanguageplatformssuchasJava. Wehavechosen
dardsdevelopedbycommunities.ItusesOGCStandards VaadinbecauseitminimizestheuseofJavascript.
(WebFeatureService, WebProcessingservice, andWeb
MappingService)toprocessspatialdataandDecisionDeck
standardsforthenon-spatialmulti-criteriadecisionanal-
ysis(MCDA)methods. Theunderlyingphilosophyisto
delegatedomainexpertisetootherimplementationsthat
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Discussion
main.Thisproblemofalackofconceptstoprovidesemantics
was already observed by (Foerster and Stoter, 2006). This
Withtheprototypeweaimtoexplorepossiblelimitationsand
issuetogetherwiththefactthatWPSprovidesverygeneric
futurechallenges.Weforinstanceneedtoexperimentwith
interface,wouldhaverequiredustospendconsiderableef-
performance. Somedesignandimplementationissueswe
forttoimplementdecisionaidingalgorithmsforspatialdata
havealreadyencounteredandaddressed.
inWPS.
Thereforewelookedatanalternativesolutionwherewe
DesignIssues
couldseparateanalysisofattributedatafromanalysisofand
operationongeometry.Andwecouldalsofindwebservices
Twomajordesignchoicesweremade.Thefirstwastomake
thatprovidedecisionsemantics.Wefoundasolutioninthe
thewebapplicationhighlymodularanddistributable. The
decisionsciencesdomainwhereopenstandardsformulti-
secondwassubstitutingWPSforDecisionDeckwebservices.
criteriadecisionaiding(MCDA)webserviceshaverecently
Dataexchangerestrictions beendevelopedintheDecisionDeckProject.Nowweonly
considerWPSfortrulygeometricpreandpostprocessing
Twochallengesinthedesignweretohandlethesizeofge-
operationssuchasoverlayanalysisorcalculationofspatial
ographicdatalayersandtheassumptionthatdatapolicies
metricsascriteria.
requiredatatoresideinsideorganizationalboundaries.Both
Finally, we abandoned WPS for decision aiding algo-
challengesviolatedourinitialdesignwherewewantedto
rithmsbecauseof thepossibilitytoprocesslarge volumes
relyfullyonexternalservices.Butnowtheapplicationhad
of data because many criteria maps may be involved and
tobecomedistributableaswellincasesdataservicescould
moreadvanceddecisionaidingmethodsaremorecomplex
notdirectlybeprovided. Sothesechallengesrequiredthat
and resource consuming too. As discussed by (Michaelis
theapplicationatleastpartiallybelocal(insidertheorganiza-
andAmes,2009)insuchsituationsitcanbemoreefficientto
tionalboundary)andcreatedtheneedtodesignadistributed
performtheprocessinglocally.
applicationusingdistributedservices.
As a solution to these challenges we consider the use
ImplementationIssues
of meta-data and delegating the analysis (e.g. calculation
ofdescriptivestatisticsbyWFS)tothedataserviceswher- Wehavefacedthreeimplementationissues. First,wehave
everpossible.Andforfurtheranalysisonthedatasetwithin hadtoaddressinconsistenciesbetweenschemaandschema
organization boundaries we deploy a utility service. This instances.Secondwehavehadtoaddresslackofinformation
servicecanperformanalysisandthencantransmitpartial aboutthedata. Herewedonotmeansomuchmeta-data,
andintermediaryresultstothemainsystem. butdescriptivedata.AndthirdwemissedopensourceGIS
UsingOSGitechnologygivesthispossibilityofdesign- toolkitswithproperdocumentation.
ingahighlymodularapplication.Anotheradvantageareits
“RemoteServices”(OSGiAlliance,2011)fordistributingmod- Inconsistencies between schema and schema in-
ulesovertheweb.Weaimtouse“RemoteServices”ofOSGi stances
tobeabletodistributeournecessarymodulesacrossorgani-
zationalboundariestogiveusopportunitytoretrieveonly We noticed that retrieval of data (or meta-data) becomes
meta-dataandpartialandintermediaryresultstofinalizethe fragilebecauseofdifferencebetweenWFSschemaandWFS
analysis. schemainstancesorbecauseofmissingschemaswhileretriev-
ingcomplextypes.SincethedataretrievalinDSMCEismade
Findingproperservicefordecisionaiding fromremoteWFSservers,whichwedonothavecontrolof,
humanerrorsorbugsinOGCServiceimplementationscan
Atthestartoftheprojectweconsideredtoimplementthe
causebaduserexperience.
multi-criteriadecisionaidingcomponentsasWebProcessing
Asasolution,weimplementedparsersthatuseadomain
Services(WPS).However,weencounteredseveralchallenge
model which is a collection of Java objects based on OGC
aboutWPSinrelationtoourproject. Onechallengewasal-
WebServiceCommonandWebFeatureServicespecifications.
ready formulated by (Friis-Christensen et al., 2007) as the
WeimplementedwithApacheCommonsDigester(Apache
absenceof“separationofgeometryandattributedata: Ge-
CommonsDigester,2011)library. Althoughthisapproach
ometryinformation,thoughnotrequiredforalargenumber
requiresimplementationofjavaobjectsfollowingthedomain
ofprocessingoperations(likeclassificationandattributenor-
model,itgivesniceflexibilityandmoretoleranceforerrors.
malisation)isdraggedalongasinformationballastslowing
ForretrievalofthedatawepreferredtouseGeoJSONformat
downtheperformanceofapplications.Examplesforspecifi-
sinceitisalighterformatcomparingtoGMLandaccessing
cationslookingintothisissuearetherelatedOGCdiscussion
attributedataiseasier.
papersontheGeolinkingService(OGC,2004b)andtheGe-
olinkedDataAccessService(OGC,2004a).”Indeedinour
Dataambiguity
applicationthemajorityofusecasesrequiredonlyattribute
dataoffeaturestobeprocessedandanalysedandthegeo- Anothermainproblemisthelackofsupportforunitsofat-
metricinformationservedjustthemapping.Theseattributes tributesanddescriptionsofattributes.InGML3,schemasfor
are,partiallyinpre-processedform,inputtoXMCDAweb unitsaredefined(Coxetal.,2002),howeverthisinformation
services.Soweabandonedourinitialideatoimplementall isnotbeingusedbytheavailableonlineWebFeatureServices
analysisasWPS. yet. Butdecisionmakerswillneedtoknowsuchattribute
AnotherreasontoabandonWPSwasthelackofconcepts informationandthecurrentlysupportsnameandtypeele-
toprovidesemanticsofthemulti-criteriadecisionaidingdo- mentsarenotsufficientforadecisionmaker.Moreover,most
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OSGeoJournalVolume10 Implementation,challengesandfuturedirectionsofintegratingservicesfromthe...
of the time, the name field is cryptic and not explanatory tobeabletocreatePOSTrequestswithXMLencodingwe
either. usedWAXlibraryforJAVA(Volkmann,2011).
Wehavenotaddressedthisissueofdataambiguityinthe
currentprototype.ForthosecaseswhereWFSareusedthat
Future directions
theuserhasnocontrolover,wewillbeprovidingannotation
toolstothedecisionmaker(enduser)unitsanddatadescrip-
Sincewehavefinishedonlyaprototypesofar,alotcanstill
tionsassumingtheuserhasothermeanstoobtainunitsand
bedone:
datadescriptions.ForthosecaseswhereusersofWFSarein
thesameorganizationastheWFSsupplier,customsolutions
• First,wewanttomodularizeoursystemswithOSGiand
couldbemadetocreateunambiguousdatainterpretation.
runitinanOSGicontainer.
• Secondweneedtocreatestatepersistency,userprofiles
Lack of WFS support for descriptive statistics about
andworkspace.
thedata
• Third,wewanttoproceedwiththeintegrationofDecision
ThegeneraluserofWFS,butcertainlytheuserofWFSvia Decktoprovideagoodamountofmulti-criteriadecision
DSCME,needsdescriptivestatisticssuchasthemaximum, aidingalgorithms.
minimum,mean,andstandarddeviation.Forinstanceofthe • Fourth,wewanttoaddpreprocessingWPSsothatusers
standarddeviationofacertainattributeissmall,ithaslittle can create a suitable criterion map from a geometry of
discriminatoryvaluebetweenthealternatives. Particularly anothermaporofgeometriesofdifferentmaps.
inspatialdatasetswherethenumberofalternatives(points, • Fifth,wehavenotaddressedtheissueofdiscoveringdata
lines,polygons,cells)canbeverylarge,descriptivestatistics but evaluation and use of OGC Catalogue Service is in
areveryimportant.Soalthoughadecisionmakermayfind ouragenda.IfDSCMEbecomesanapplicationthatruns
thecriterionthatusestheattributeimportant,ifitisnotdis- withinorganizationsitwillneedtobecustomizedtouse
criminating,itmightevenbediscardedaltogether.Butalso theorganizationalcatalogue.
forproperlystyledWMSvisualization,notonlyinDSMCE, • Sixth,becauseofthechallengesindataformatsandavail-
maximumandminimumvaluesareimportant. abletoolsthatsupportWebCoverageService(WCS)we
WeexpectedmoresupportfromOGCdataservices(WFS, started our project with vector support. However we
OGC).Descriptivestatisticsareoptionalservicesinsection knowofverygoodexperienceofusefulnessofraster-based
13.3.2ofWFS1.1.0specification(Vretanos,2005):"Theschema SMCEwiththeSMCEmodulewedevelopedearlierinthe
oftheFilterCapabilitiesSectionisdefinedintheFilterEncod- desktopILWISGIS(52North,2011)andwouldliketoin-
ingImplementationSpecification.Thisisanoptionalsection. cludearasterversionintheagenda.
Ifitexists,thentheWFSshouldsupporttheoperationsadver- • Seventh,wewanttodevelopthepotentialforcollaborative
tisedtherein.IftheFilterCapabilitiesSectionisnotdefined, decision making and explore new decision aiding algo-
thentheclientshouldassumethattheserveronlysupports rithms.
theminimumdefaultsetoffilteroperatorsasdefinedinthe • Andfinally,weknowchainingservicesandmanagingit
FilterEncodingImplementationSpecification." bytheuseofworkflowmanagersisveryinteresting.Tobe
abletosatisfydifferentandcomplexscenariosindecision
Sincethesedescriptivestatisticsarecrucialfordecision
makingwewouldliketodevelopaworkflowmechanism
making,weimplementedasimplestatisticsfacilitybyfetch-
for our application. We believe prior to that we need a
ingthewholefeaturesetandusingApacheCommonsMath
gooddegreeofmodularityinourapplication.
librarytocomputedescriptivestatistics.Weconsideredcheck-
ingifafilterisavailablefromaWFSinthecapabilitiesre-
sponse,butthisburdensoursystemwithcomplexityofcheck- Conclusions
inganderrorhandling. Althoughwehaveaworkingsolu-
tion,itbreakswithourinitialideaofusingthemeta-dataand
Wehavepresentedaprototypeofdistributedspatialmulti-
capabilitiesofexternalservicespriortothecoreanalysis.
criteriaevaluationwebapplication,whichintegratesOGC
andDecisionDeckwebservices,therebydelegatingfunction-
Lack of lightweight open source GIS toolkits with
alitytotherespectiveexpertisedomains.Itisdistributed,not
properdocumentation
onlyintheconceptofdistributedcomputing,becauseitcan
As described under section design issues, the majority of collectdatafromdistributeddatasources,i.e. WebFeature
operationsinDSMCEonlyuseattributeinformation,notgeo- Services(WFS),or,ifdatacannotbeexchangedbecauseof
metricinformation.HoweverintheavailableopensourceGIS datapolicies,datavalue,bandwidth,andotherreasons,it
toolkits,datastructuredesignsarenaturallyaffectedbythe canbedistributedtothesedatasourcesandcollectonlythe
traditionalstructureofGISdatawherefeaturesareacompo- intermediaryoutputs. Also,decisionmakersaregeograph-
sitionofgeometryandattributes.Wealsonoticedmanyinter- icallydistributedorintime. Anddevelopmentofitcanbe
dependenciesbetweenlibrariesandlackofdocumentation distributed, given the open source nature, provided good
aboutdependencies.Soitbecomesreallyhardtousetoolkits programmingpracticesandsystemsaremaintained.
forourlighterneedsandwedidnotfindalightweightGIS We have described its workings and architecture. But
toolkit which is efficient for attribute data and helpful for importantlywehaveexplainedseveraldesignandimplemen-
simplemapping.Thesedifficultiesandpoordocumentation tationsolutionswhichwehadtofollowbecauseofpartially
motivatedustoimplementlightweightOGCserviceclients functioningimplementationsofOGCstandards. Weareof-
forWFSandWMS.ForthatpurposeweusedApacheCom- feringanecdotalevidenceofshortcomingsofthesestandards
monsHTTP(ApacheCommonsHttpClient,2011)libraryand butalsoofopensourcesoftware.Itwouldbeworthwhileto
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OSGeoJournalVolume10 FOSS4G2011ConferenceProceedings
doamoresystematicanalysisbutthatisbeyondthescopeof EnvironmentalManagement,Amsterdam,FreeUniversity
thispaper. Amsterdam.
13. KESHKAMAT,S.S.,LOOIJEN,J.M.&ZUIDGEEST,M.H.
P.2009.Theformulationandevaluationoftransportroute
Acknowledgements
planningalternatives: aspatialdecisionsupportsystem
fortheViaBalticaproject, Poland. JournalofTransport
TheForeStClimprojecthasreceivedEuropeanRegionalDe-
Geography,17,54-64.
velopmentFundingthroughINTERREGIVBNEW.
14. MALCZEWSKI,J.2006.GIS-basedmulticriteriadecision
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