NAME

       Catmandu::Importer::RDF - parse RDF data

SYNOPSIS

       Command line client "catmandu":

         catmandu convert RDF --url http://d-nb.info/gnd/4151473-7 to YAML

         catmandu convert RDF --file rdfdump.ttl to JSON

         # Parse the input into on JSON document per triplet. This is the
         # most memory efficient (and fastest) way to parse RDF input.
         catmandu convert RDF --triples 1 --file rdfdump.ttl to JSON

         # Transform back into NTriples (conversions to and from triples is the
         # most efficient way to process RDF)
         catmandu convert RDF --triples 1 --file rdfdump.ttl to RDF --type NTriples

         # Query a SPARQL endpoint
         catmandu convert RDF --url http://dbpedia.org/sparql
                              --sparql "SELECT ?film WHERE { ?film dct:subject <http://dbpedia.org/resource/Category:French_films> }"

         catmandu convert RDF --url http://example.org/sparql --sparql query.rq

         # Query a Linked Data Fragment endpoint
         catmandu convert RDF --url http://fragments.dbpedia.org/2014/en
                              --sparql "SELECT ?film WHERE { ?film dct:subject <http://dbpedia.org/resource/Category:French_films> }"

       In Perl code:

           use Catmandu::Importer::RDF;
           my $url = "http://dx.doi.org/10.2474/trol.7.147";
           my $rdf = Catmandu::Importer::RDF->new( url => $url )->first;

DESCRIPTION

       This Catmandu::Importer can be use to import RDF data from URLs, files or input streams,
       SPARQL endpoints, and Linked Data Fragment endpoints.

       By default an RDF graph is imported as single item in aREF format (see RDF::aREF).

CONFIGURATION

       url URL to retrieve RDF from.

       type
           RDF serialization type (e.g. "ttl" for RDF/Turtle).

       base
           Base URL. By default derived from the URL or file name.

       ns  Use default namespace prefixes as provided by RDF::NS to abbreviate predicate and
           datatype URIs. Set to 0 to disable abbreviating URIs.  Set to a specific date to get
           stable namespace prefix mappings.

       triples
           Import each RDF triple as one aREF subject map (default) or predicate map (option
           "predicate_map"), if enabled. This is the most efficient way to process large input
           files. All the processing can be streamed.

       predicate_map
           Import RDF as aREF predicate map, if possible.

       file
       fh
       encoding
       fix Default configuration options of Catmandu::Importer.

       sparql
           The SPARQL query to be executed on the URL endpoint (currectly only SELECT is
           supported).  The query can be supplied as string or as filename. The importer tries to
           automatically add missing PREFIX statements from the default namespace prefixes.

       sparql_result
           Encoding of SPARQL result values. With "aref", query results are encoded in aREF
           format, with URIs in "<" and ">" (no qNames) and literal nodes appended by "@" and
           optional language code. By default (value "simple"), all RDF nodes are simplfied to
           their literal form.

       cache
           Set to a true value to cache repeated URL responses in a CHI based backend.

       cache_options
           Provide the CHI based options for caching result sets. By default a memory store of
           1MB size is used. This is equal to:

               Catamandu::Importer::RDF->new( ...,
                   cache => 1,
                   cache_options => {
                       driver => 'Memory',
                       global => 1,
                       max_size => 1024*1024
                   });

       speed
           If set to a true value, then write RDF file processing speed on the STDERR as number
           of triples parsed per second.

METHODS

       See Catmandu::Importer.

SEE ALSO

       RDF::Trine::Store, RDF::Trine::Parser