iri data library faceted search : an example of
DESCRIPTION
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 http://iridl.ldeo.columbia.edu/ontologies/. Faceted Search. - PowerPoint PPT PresentationTRANSCRIPT
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
http://iridl.ldeo.columbia.edu/ontologies/
Faceted Searchhttp://iridl.ldeo.columbia.edu/ontologies/query2.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• Returned items also have structure (sub-items and superseded items are not shown)
Architectural Features of the search
• 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
http://iridl.ldeo.columbia.edu/ontologies/query2.pl
Search Interface as Multiple Ontologies
Search Interface
Users
Datasets
Search Ontology
Dataset Ontology
Additional Semantics
Ontology Types
• Attribute Ontology (e.g. Dataset)
• Object Ontology (essential for crosswalk)
• Term Ontology (e.g. search ontology)
Attribute Ontology
• Subjects are the only type-object
• Predicates are “attributes”
• Objects are datatype
• Isomorphic to simple data tables
• Isomorphic to netcdf attributes of datasets
• Some faceted browsers: predicate = facet
Object Ontology
• Objects are object-type• Isomorphic to “belongs to”• Isomorphic to multiple data tables connected by
keys• Express the concept behind netcdf attributes
which name variables • Concepts as objects can be cross-walked• Concepts as object can be interrelated
Example: controlled vocabulary
{variable} cfatt:standard_name {“string”}
Where string has to belong to a list of possibilities.
{variable} cfobj:standard_name {stdnam}
Where stdnam is an individual of the class cfobj:StandardName
Example: controlled vocabulary
Bi-direction crosswalk between the two is somewhat trivial, which means all my objects will have both
cfatt:standard_name
and
cfobj:standard_name
Example: controlled vocabulary
If I am writing software to read/write netcdf files, I use the cfatt ontology and in particular cfatt:standard_name
If I am making connections/cross-walks to other variable naming standards, I use
cfobj:standard_name
Term Ontology
Concepts as individuals
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 nuancedtagging 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:isPartOf {item2} dcterm:isReplacedBy {item2}
{item} trm:isDescribedBy {term}
{term} a {facet} of {taxa} of {trm:Term},{facet} a {trm:Facet}, {taxa} a {trm:Taxa},{term} trm:directlyImplies {term2}
Faceted Search w/Querieshttp://iridl.ldeo.columbia.edu/ontologies/query2.pl?...
RDF Architecture
RDF
RDF RDF
RDF
RDF RDF
RDF
RDF RDF
RDF
RDF
RDF RDF
RDF
RDF RDF
Virtual (derived) RDF
queries queries queries
Data ServersOntologies
MMI
JPL
StandardsOrganizations
Start Point
RDF Crawler
RDFS SemanticsOwl SemanticsSWRL Rules
SeRQL CONSTRUCT
Search Queries
LocationCanonicalizer
TimeCanonicalizer
Sesame
Search Interface
bibliography
IRI RDF Architecture
Cast of Characters
NC – netcdf data file format
CF – Climate and Forecast metadata convention for netcdf
SWEET - Semantic Web for Earth and Environmental Terminology (OWL Ontology)
IRIDL – IRI Data Library
CF attributes
SWEET Ontologies(OWL)
Search Terms
CF Standard Names(RDF object)
IRIDL Terms
NC basic attributes
IRIDLattributes/objects
SWEET as Terms
CF Standard NamesAs Terms
Gazetteer Terms
CF data objects
Location
See Also
• http://iridl.ldeo.columbia.edu/ontologies/
• http://iri.columbia.edu/~benno/Talks/AGU2007Poster.pdf