1 / 21

Linked Data Practices for the Geospatial Community

Linked Data Practices for the Geospatial Community. Talk subtitle. Presented at GEOSS Workshop on Climate Boulder Colorado, 23 September 2011 Stephan Zednik, zednis@rpi.edu RPI / Tetherless World Constellation. Value Proposition of Linked Data. Discover

chance
Download Presentation

Linked Data Practices for the Geospatial Community

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Linked Data Practices for the Geospatial Community Talk subtitle Presented at GEOSS Workshop on Climate Boulder Colorado, 23 September 2011 Stephan Zednik, zednis@rpi.edu RPI / Tetherless World Constellation

  2. Value Proposition of Linked Data • Discover • Web resources ‘easy’ to generate and link to • Access • Leverage HTTP methods • Integrate • RDF is a standard mechanism for specifying the existence and meaning of connections between items described in the data • Use • Web standards for data access and representation simplify data consumption while providing (extreme) expressivity

  3. Principles of Linked Data There are 4 principle expectations (rules) for Linked Data • Use URIs as names for things • Use HTTP URIs so that people can look up those names • When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL) • Include links to other URIs, so that they can discover more things

  4. World Wide Web of Data!

  5. Linked Data Languages • SKOS (Simple Knowledge Organizational System) • Thesauri, Taxonomies, Topical Hierarchies • RDFS (RDF Schema) • Vocabularies • OWL (Web Ontology Language) • Ontologies • RDFS+ • RDFS + Subset of OWL

  6. Reuse • Key factor in re-usability of data: structure • Regular and structured is • Easier to find • Easier to make tools for • More likely to be referenced • and therefore beneficiary of network effect

  7. Re-use Concerns • Usage & Uptake • Maintenance & Governance • Coverage • Expressivity • Modularity

  8. Example: SWEET 2 Dependency Graph

  9. Finding Vocabularies • No current definitive directory to find existing vocabularies • SchemaWeb, SchemaCache, Swoogle • Statistics on usage of vocabularies in the wild • Section 2.3 of the State of the LOD Cloud • http://lod-cloud.net/state#terms

  10. Using Vocabularies • If suitable terms are found, they should be re-used • Maximizes potential for consumption • Network effect on re-used vocabulary • New terms should be mapped to well-established existing vocabularies • Standards bodies useful to establish & promote vocabularies • Network effect long-term driving factor • Example: FOAF

  11. W3C Geo Vocabulary • Basic RDF vocabulary that provides a namespace for representing latitude, longitude, and other spatially located things using WGS84 as a reference datum • http://www.w3.org/2003/01/geo/ • Wideusage, but far toosimple for GIS tools <rdf:RDFxmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#"> <geo:Point> <geo:lat>55.701</geo:lat> <geo:long>12.552</geo:long> </geo:Point> </rdf:RDF>

  12. OGC GeoSPARQL • Includes • RDF/OWL Vocabulary for representing spatial information • A set of functions for spatial computations • A set of query transformation Rules • Expressivity for GIS tool requirements • http://www.opengeospatial.org/projects/groups/geosparqlswg

  13. OGC GeoSPARQL RDF

  14. Discovering Linked Data • ‘Standard’ discovery of linked data is via other linked data… • OpenSearch • Version 1.1 Geo extension (very basic) • Semantics? • DataCasting • ProductCasting • InventoryCasting • ServiceCasting

  15. Querying Linked Data • SPARQL Endpoint • Requires understanding of structure • Generally domain agnostic • Faceted Browsing • Pelorus • http://clarkparsia.com/pelorus • S2S • http://tw.rpi.edu/web/project/sesf/workinggroups/s2s • Supports Widgets

  16. SPARQL Endpoint Web Browser

  17. Pelorus

  18. S2S Faceted Browser

  19. Services & Linked Data • SOAP Web Services and Linked Data are not complementary • Document exchange vs Web of Data • SOAP ignores HTTP access semantics • REST (Representational State Transfer) • HTTP as a mechanism for retrieval of resource representations exposed via URIs • Resource Orientated Architecture (ROA) • Stateless interactions • Linked Data and RESTful services can be complementary • Will take care in design

  20. Questions? • Stephan Zednik, zednis@rpi.edu

  21. References • Tom Heath and Christian Bizer (2011) Linked Data: Evolving the Web into a Global Data Space (1st Edition) Synthesis Lectures on the Semantic Web: Theory and Technology, 1:1, 1-136. Morgan & Claypool. • DOI: 10.2200/S00334ED1V01Y201102WBE001 • http://linkeddatabook.com/editions/1.0/ • GeoSPARQL SWG • http://www.opengeospatial.org/projects/groups/geosparqlswg • JPL Datacasting • http://datacasting.jpl.nasa.gov/ • Pelorus • http://clarkparsia.com/pelorus • S2S • http://tw.rpi.edu/web/project/sesf/workinggroups/s2s

More Related