RDF::Q...iption(3pm)

💖 RDF::Query::ServiceDescription 💖

okay so bestie, welcome to the RDF::Q...iption(3pm) page — it lives in the User Contributed Perl Documentation section, and it's literally the whole glow-up guide for describing federated query data sources. yes that's a real thing and yes it's as iconic as it sounds 💅

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✨ VERSION ✨

this doc describes RDF::Query::ServiceDescription version 2.919. slay.

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🌸 METHODS 🌸

• new ( $service_uri, %data )

that's it. that's the description the manpage gave us. no notes, no elaboration, just vibes 💀 (the constructor is doing constructor things, iykyk)

• new_from_uri ( $url )

makes a whole new service description object for you, using the DARQ-style service description data sitting over at $url. like, it goes and fetches it, bestie 🦋

• new_with_model ( $model )

same energy as the one above, except instead of a URL it uses the DARQ-style service description data that's already loaded up inside the $model object you hand it. no fetching required ✨

• url

hands you back the endpoint URL of the service. the actual address. the main character 📍

• size

returns the number of triples the service claims to have. "claims" is doing a lot of heavy lifting in that sentence, bestie, but okay 👑

• label

returns the label of the service. cute little name tag 🎀

• definitive

returns true if the endpoint claims to have definitive information. and if it doesn't claim that? you get false. iconic behaviour ⭐

• 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 these 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

the way that struct is laid out... obsessed 😭

• patterns

returns an ARRAY reference of RDF::Query::Algebra::BasicGraphPattern objects — these represent the common patterns the endpoint uses. it's giving "here's what I'm known for" 🌈

• computed_statement_generator

returns a closure that's appropriate for passing to RDF::Query->add_computed_statement_generator, so it can generate statement iterators for the remote service. very demure, very delegation 💅

this closure takes ($query, $bridge, \%bound, $subj, $pred, $obj [, $context ] ) as its arguments, and it returns either undef — if no statements can be generated given the arguments — or an RDF::Trine::Iterator::Graph iterator holding the statements matching $subj, $pred, $obj [, $context ]. two outcomes, one closure, no cap 🫶

• answers_triple_pattern ( $triple )

returns true if the service this object is describing can actually answer queries made up of the triple pattern you supplied. vibe check passed ✅

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👑 AUTHOR 👑

Gregory Todd Williams <gwilliams@cpan.org>

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that's the whole page bestie, you ate it 🍓 this was written against perl v5.40.1 and dated 2025-08-18 — go forth and describe those federated data sources, periodt 💜🧚