Semantic Web underpinnings of the IRI Data Library
Semantic Web underpinnings of the IRI Data Library • Semantic Web as a Framework for Multiple Metadata • IRI Data Library: presenting Data in multiple frameworks • Pure RDF Faceted Data Search • Metadata interoperability using adiabatic XML Schema to OWL mapping http: //iridl. ldeo. columbia. edu/ontologies/
blind monks examining an elephant Multiple partial representations of objects described by data John Godfrey Saxe (1816 -1887)
Semantic Web as a Framework for Multiple Metadata: The Data Problem Datasets Users
The Tool Interface Tools Datasets Users
Standard Metadata Schema/Data Services Tools Datasets Users
Many Data Communities
Super Schema Standard metadata schema Standard Metadata Schema Tools Datasets Users Standard Metadata Schema Tools Users Datasets
RDF Data Model Exchange Standard metadata schema RDF
RDF Architecture Virtual (derived) RDF
Where we are coming from – the IRI Data Library presenting Data in multiple frameworks
IRI Data Library Overview URL/URI for data, calculations, figs, etc
Data Flow based Analysis with explicit semantics data analysis data
IRI Data Collection Ocean/Atm “geolocated by lat/lon” multidimensional spectral harmonics equal-area grids GRIB grid codes climate divisions GIS “geolocation by vector object or projection metadata”
IRI Data Collection
IRI Data Collection
IRI General Data Tools Data Page
IRI General Data Tools Data Viewer
Calculations: svd (link: svdview) (link: svd results dataset) (link: svd documentation)
WMS and KML: land cover (link: figure page)
IRI Map Room Malaria Early Warning System • Front page illustrates most recent dekadal rainfall estimates (FEWS RFE) • Administrative and epidemiological overlays available • Change dates to view different time periods • Click and drag box across map to zoom
IRI Data Library Faceted Search: an example of • RDF-based faceted search for climate data • Drawing on multiple ontologies to build an application • Using inference to connect ontologies describing different parts of the framework
Search Interface as Multiple Ontologies Additional Semantics Dataset Ontology Search Interface Datasets Users
Faceted Search http: //iridl. ldeo. columbia. edu/ontologies/query 2. pl? . . .
Distinctive Features of the search • Search terms are interrelated • terms that describe the set of returns are displayed (spanning and not) • Returned items also have structure (subitems and superseded items are not shown)
Architectural Features of the search http: //iridl. ldeo. columbia. edu/ontologies/query 2. pl • Interface is generated from a set of Terms connected to a set of Items • Multiple search structures possible • Multiple languages possible • Search structure is kept in the database, not in the code
Term Ontology Concepts as individuals (unlike conceptual ontology with concepts as classes) Simple Knowledge Organization System (SKOS) is a prime example The ontology used here is slightly different than SKOS: facets are classes of terms rather than being top_concepts
Nuanced tagging Concepts as objects can be interrelated: specific terms imply broader terms Object ends up being tagging with terms ranging from general to specific. Search can then be nuanced tagging can proceed in absence of perfect information
Faceted Search Explicated
Search Interface • Items (datasets/maps) • Terms • Facets • Taxa
Search Interface Semantic API {item} dc: title dc: description rss: link iridl: icon dcterm: is. Part. Of {item 2} dcterm: is. Replaced. By {item 2} {item} trm: is. Described. By {term} a {facet} of {taxa} of {trm: Term}, {facet} a {trm: Facet}, {taxa} a {trm: Taxa}, {term} trm: directly. Implies {term 2}
Faceted Search w/Queries http: //iridl. ldeo. columbia. edu/ontologies/query 2. pl? . . .
RDF Architecture Virtual (derived) RDF
IRI RDF Architecture MMI Data Servers Ontologies JPL bibliography Start Point Standards Organizations RDF/XML-Schema Crawler XML Schema to OWL translation Owl Semantics SWRL Rules Se. RQL CONSTRUCT Sesame Search Queries Search Interface Location Canonicalizer Time Canonicalizer
Cast of Characters NC – netcdf data file format CF – Climate and Forecast metadata convention for netcdf (includes controlled vocabulary for physical quantities) SWEET - Semantic Web for Earth and Environmental Terminology (OWL Ontology) IRIDL – IRI Data Library
NC basic attributes CF attributes IRIDL attributes/objects CF data objects SWEET Ontologies (OWL) CF Standard Names (RDF object) Location CF Standard Names As Terms SWEET as Terms Gazetteer Terms Search Terms IRIDL Terms
XML Schema to OWL ontologies • Semantically-mediated translation between Web Coverage Service (WCS) and OPe. NDAP (data as multiple-dimension variable) • WCS is defined in XML Schema (57!) • Sample Schema to OWL Translation • Method to return JDOM element (XML) containing requested XML property from RDF triple-store (element maps to (Resource, class) pair) • Sample Datasets/Coverages
Please Visit IRI Data Library: http: //iridl. ldeo. columbia. edu/ IRI ontology work: http: //iridl. ldeo. columbia. edu/ontologies/ Or contact: Benno Blumenthal John del Corral Haibo Liu
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