Catman...er::RDF(3pm)

💖 Catmandu::Importer::RDF 💖

okay bestie, listen up, because this one is genuinely iconic. we're talking about Catmandu::Importer::RDF, a Perl module that lives in the User Contributed Perl Documentation (that's the 3pm section, iykyk) and its whole entire job is parsing RDF data. yes. RDF data. she's a whole vibe and she knows it. 🦋

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✨ NAME ✨

Catmandu::Importer::RDF — parse RDF data. that's it, that's the name, no notes. 💅

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🎀 SYNOPSIS 🎀

so there's a command line client called catmandu and honestly? she eats. here's how you'd use her:

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> }"

and if you're doing it in Perl code, because you're a main character who writes actual 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;

periodt. 💅

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🌸 DESCRIPTION 🌸

the way that this Catmandu::Importer can just... import RDF data from literally everywhere? URLs, files, input streams, SPARQL endpoints, AND Linked Data Fragment endpoints. she contains multitudes fr fr. 🫶

and by default, an RDF graph gets imported as a single item in aREF format (go look at RDF::aREF if you wanna know more, bestie, I'm not gonna gatekeep).

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👑 CONFIGURATION 👑

here's every single knob you can turn. all of them. no skips, no skimming, we respect the config here. ⭐

• url — the URL you're retrieving your RDF from. simple as that.
• type — the RDF serialization type (so like, ttl for RDF/Turtle, that kinda thing).
• base — the base URL. if you don't set it, she derives it from the URL or the file name all by herself. independent queen.
• ns — uses the default namespace prefixes that RDF::NS provides to abbreviate predicate and datatype URIs. set it to 0 to turn off URI abbreviating entirely. set it to a specific date if you want stable namespace prefix mappings. iykyk.
• triples — imports each RDF triple as one aREF subject map (that's the default) or a predicate map (if you turn on the predicate_map option). this is THE most efficient way to process big input files, because all the processing can be streamed. slay.
• predicate_map — imports RDF as an aREF predicate map, if possible. if possible!! 🫠
• file, fh, encoding, fix — the default configuration options of Catmandu::Importer. the classics.
• sparql — the SPARQL query to run against the URL endpoint (as of right now, only SELECT is supported, okay?). you can hand her the query as a string OR as a filename. she also tries to automatically add any missing PREFIX statements using the default namespace prefixes, which is very generous of her honestly. 👑
• sparql_result — the encoding of SPARQL result values. with aref, query results get encoded in aREF format, with URIs wrapped in < and > (no qNames) and literal nodes appended with @ plus an optional language code. by default (that's the value simple), all RDF nodes get simplfied down to their literal form.
• cache — set this to a true value and she'll cache repeated URL responses in a CHI based backend. obsessed.
• cache_options — gives you the CHI based options for caching result sets. by default a memory store of 1MB size is used, which is exactly equal to this:

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

• speed — set this to a true value and she writes the RDF file processing speed to the STDERR as the number of triples parsed per second. little performance report, as a treat. 🔥

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⭐ METHODS ⭐

go look at Catmandu::Importer. that's the whole thing. I said what I said. 💜

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🌈 SEE ALSO 🌈

• RDF::Trine::Store
• RDF::Trine::Parser

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okay that's the whole page bestie, you made it, I'm so proud of you. 🎀 this beauty ships as perl v5.36.0, dated 2022-12-06 — and yeah, the header up top calls her Catman...er::RDF(3pm) because apparently we ran out of room, but you and me both know her full government name. go parse some RDF. slay 💖✨