Name: Jim Jones
Making the Web of Data Available via Web Feature Services
Jim Jones, Werner Kuhn, Carsten Keßler and Simon Scheider
17th AGILE Conference 2014, Castellón, Spain
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
2
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
3
WFS Server
Shapefile
Database
GIS Client
Web Feature Service (WFS)
KVP
- Data Analysis - Spatial Operations- Generate New Maps...
XML (GML)
Name: Jim Jones
4
Number of hospitals in the cities around the flooding area
Where to get this information?
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
Low InteroperabilityData stored in silos (e.g. databases, shapefiles) and
external sources can't be used in one query.
inefficient maintenanceTable of Contents not easily updated
(e.g. add new data means add new database fields, which has to done by a GIS expert / DBA)
WFS Issues
We propose an LOD based solution called LOD4WFS!
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
6
OutlineWFS andLOD
LOD4WFS Adapter
Solution Evaluation
Conclusion andFuture Work
Name: Jim Jones
7
Linked Open Data
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
Linked Open Data
“linked open data describes a method of publishing structured data so that it can be interlinked and become more useful.”
8
Raw data, now!
Tim Berners-Lee
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
.
LOD Cloud
Geometry
Table ofContents
Name: Jim Jones
10
GIS Client
Research Question
LOD Cloud
How to efficiently make geographic LOD datasets discoverabele by current GIS?
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
11
Related Issues
How to read geographic LOD without modifying the current GIS?
How to develop a solution that is both platform and GIS independent?
Is performance an issue when querying geographic LOD datasets?
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
12
Proposed Solution
GIS ClientLOD Cloud
LOD4WFSAdapter
Creates an intermediate WFS layer “on top” of the LOD cloud
Provides LOD datasets in a format understood by GIS based on OGC Standards.
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
13
LOD4WFS overview in 6 Steps...
LOD4WFSAdapter
GIS Client
KVP
Triple Store
SPARQL
1. Client sends request2. Adapter translates GIS request to SPARQLand performs query.
3. Triple Store processesSPARQL query.
4. Triple Store returnsSPARQL result set.
5. Adapter translates result set and delivers
WFS document to the GIS.
6. GIS gets the WFS document.
XML (GML)RDF
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
GIS ClientLOD Cloud
From this...
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
15
Data Access and Format
Standard Data Access
Federated Data Access
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
16
Standard Data Access
Triple StoreLOD4WFSAdapter
SPARQL
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
17
Standard Data AccessData Structure (Including Meta-Data)
Named Graph
Title DescriptionFeatures
Geometries Attributes (TOC)
...
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
18
Standard Data AccessData Structure
<http://ifgi.lod4wfs.de/graph/municipalities> dct:title "Brazilian Municipalities"^^xsd:string ; dct:abstract "Municipalities of the Brazilian Federal States."^^xsd:string ; dct:subject "municipalities boundaries"^^xsd:string .
my:FEATURE_RECIFE a geo:Feature ; rdf:ID "2611606"^^xsd:integer ; dc:description "Recife"^^xsd:string ; geo:hasGeometry my:GEOMETRY_RECIFE .
my:GEOMETRY_RECIFE a geo:Geometry ;geo:asWKT "<http://www.opengis.net/def/crs/EPSG/ 0/4326>
POLYGON ((-35.0148559599999984 -8.0564907399999992, -34.9939074400000010 -8.0493884799999993,...-35.0148559599999984 -8.0564907399999992))"^^sf:wktLiteral .
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
19
Federated Data Access
LOD CloudLOD4WFSAdapter
Customized SPARQL
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
20
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
21
DBpedia
Ordnance Survey
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
22
Name: Jim Jones
Making the Web of Data Available via Web Feature Services
23
Name: Jim Jones
24
Solution Evaluation (preliminary results)
Geoserver (WFS)
Shapefiles
PostGIS
shp2rdf.R
Parliament Fuseki OWLIM Lite
Ubuntu Server 12.04 LTS Linux 3.2.0-58-generic (amd64)Intel(R) Xeon(R), CPU E5530 @ 2.40GHz, Dual Core8GB RAM
Vocabularies: GeoSPARQL andDublin Core
Geometry Encoding:Well Known Text (WKT)
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
25Making the Web of Data Available via Web Feature Services
Test Datasets
Test Scenario SHP Size DB Size DB Records Turtle file Triples
1 – Brazilian Cities 11.2 MB 16 MB5799
28.7 MB 86988
2 – Amazon Rivers 45 MB 55 MB18690
113.8 MB 359206
3 – Amazon Vegetation 173.2 MB 183 MB 39083416.1 MB 703497
Source: Brazilian Institute of Geography and Statisticshttp://www.ibge.gov.br
Name: Jim Jones
LOD4WFS
GeoserverPostGIS
ParliamentFuseki
OWLIM Lite
~38.2 sec.
~38.87 sec. ~38.7 sec.
~38.85 sec.cURL
GetFeature Request – Scenario 1 (Brazilian Cities – 86988 Triples)
Name: Jim Jones
LOD4WFS
GeoserverPostGIS
ParliamentFuseki
OWLIM Lite
~2:36.2 min.
~2:38.15 min. ~2:38.11 min.
~2:38.0 min.cURL
GetFeature Request – Scenario 2 (Amazon Rivers – 359206 Triples)
Name: Jim Jones
LOD4WFS
GeoserverPostGIS
ParliamentFuseki
OWLIM Lite
~8:35.6 min.
~8:44:7 min. ~8:44:0 min.
~8:39:0 min.cURL
GetFeature Request – Scenario 3 (Amazon Vegetation – 703497 Triples)
Name: Jim Jones
Conclusions
29Making the Web of Data Available via Web Feature Services
Name: Jim Jones
Future Work (Potential for growth!)
30
- Implement spatial queries (GeoSPARQL)- Implement WFS-T (Insert, Update, Delete).- Publish WFS contents as LOD!
Usage of LOD in GIS is perfectly feasible
- LOD4WFS provides a suitable platform forbridging GIS and LOD and querying distributed sources.- The proposed approach enables thematic queries to compose the geometries' table of contents.- Preliminary tests showed that current triple stores provide competitive speed compared to databases
Making the Web of Data Available via Web Feature Services
Name: Jim Jones
31
Obrigado!
Making the Web of Data Available via Web Feature Services
https://github.com/lodum/lod4wfs
