NAME¶

RDF::Query::ServiceDescription - Class for describing federated query data sources.

VERSION¶

This document describes RDF::Query::ServiceDescription version 2.908.

METHODS¶

"new ( $service_uri, %data )"

"new_from_uri ( $url )"

Creates a new service description object using the DARQ-style service description data located at $url.

"new_with_model ( $model )"

Creates a new service description object using the DARQ-style service description data loaded in the supplied $model object.

"url"

Returns the endpoint URL of the service.

"size"

Returns the number of triples the service claims to have.

"label"

Returns the label of the service.

"definitive"

Returns true if the endpoint claims to have definitive information.

"capabilities"

Returns an ARRAY reference of capabilities (as HASH references) of the service. Each capability will contain information on size, selectivity, any subject-object filter, and required predicate, with the following classes:

 

  $capability->{object_selectivity} # RDF::Trine::Node::Literal xsd:double
  $capability->{sofilter} # RDF::Query::Expression
  $capability->{size} # RDF::Trine::Node::Literal xsd:integer
  $capability->{pred} # RDF::Trine::Node::Resource
    

"patterns"

Returns an ARRAY reference of RDF::Query::Algebra::BasicGraphPattern objects representing common patterns used by the endpoint.

"computed_statement_generator"

Returns a closure appropriate for passing to "RDF::Query->add_computed_statement_generator" to generate statement iterators for the remote service.

 

This closure takes "($query, $bridge, \%bound, $subj, $pred, $obj [, $context ] )" as arguments and returns either "undef" if no statements can be generated given the arguments, or a "RDF::Trine::Iterator::Graph" iterator containing statements matching "$subj, $pred, $obj [, $context ]".

"answers_triple_pattern ( $triple )"

Returns true if the service described by this object can answer queries comprised of the supplied triple pattern.

AUTHOR¶

 Gregory Todd Williams <gwilliams@cpan.org>