rdf

RDF models as Clojure(script) namespaces

Overview

This project provides tools for managing RDF data using Apache Jena and Aristotle within Clojure(script), allowing easy manipulation and querying of RDF terms organized into multimethod hierarchies.

Configuration

Below is a configuration example for setting up the Universal Translator, which facilitates RDF model management through a structured namespace.

{:asami  {:sc/create-fn net.wikipunk.asami/map->Connection
          :uri          "asami:mem://.vocab"}
 :vocab  {:sc/create-fn net.wikipunk.rdf/map->UniversalTranslator
          ;; add components that require RDF vocabulary and optionally
          ;; provide asami or datomic as an environment
          :sc/refs      {:env :asami}
          ;; the string to prefix the namespace generated for your rdf models
          :ns-prefix    "net.wikipunk.rdf."
          ;; the project relative path to output the namespaces
          :output-to    "src/cljc/net/wikipunk/rdf/"
          :context      []
          ;; set to true to materialize MOP inferences in classes
          :finalize?    true
          ;; (optional) import private vars from one namespace as
          ;; public ones in another before starting the system
          :import-from  {net.wikipunk.rdf.aio net.wikipunk.rdf.obo}}}

This is a schematic configuration map which is assembled and started using component.

Boot namespace

The convention is to place a file containing the JSON-LD context for your project organized into a Clojure namespace called boot.cljc.

For example, for this project it is located at src/cljc/net/wikipunk/boot.cljc.

:context

Provide a list of namespaces that are tagged with :rdf/type :jsonld/Context in their metadata. These namespaces contain defs of :rdfa/PrefixMapping instances which can be emitted (via net.wikipunk.rdf/emit) to generate the Clojure namespaces from the provided metadata.

For an example see the net.wikipunk.boot namespace which corresponds to the RDFa 1.1 initial context;

(def as
  "Activity Vocabulary"
  {:dcat/downloadURL "net/wikipunk/boot/activitystreams2.ttl"
   :rdfa/uri         "https://www.w3.org/ns/activitystreams#",
   :rdfa/prefix      "as",
   :rdfs/isDefinedBy {:xsd/anyURI "https://www.w3.org/TR/activitystreams-vocabulary/"},
   :rdf/type         :rdfa/PrefixMapping})

:rdf/type is :rdfa/PrefixMapping which has two slots:

:rdfa/uri contains the URI of the vocabulary :rdfa/prefix contains the prefix string used which expands to the uri

:dcat/downloadURL is used to declare the location of the RDF document to download when emitting a Clojure namespace and override the value of :rdfa/uri.

:emit should be set to false if you do not want to emit this prefix mapping as a Clojure namespace

:private should be set to true if you want to emit vars that are declared in another RDF model, this should probably not be used unless you know what you're doing and want to override other definitions

:namespaces should be provided if you want to manually override the prefix mappings declared in the RDF model

:dev

Requirement

• Clojure CLI
• Datomic local

clojure -A:dev

(reset)

Assuming you have started the system and are in the dev namespace use the following functions to explore the vocabulary:

Terms are identified by namespace-qualified keywords where the namespace part is the prefix of the vocabulary and the name part is the name of the term in that vocabulary.

For example, for the namespace "schema" and term "Movie", you can treat the following keyword as its identifier:

:schema/Movie

All metaobjects that are available to the system must have a :db/ident associated with them when the system is started.

(datafy :schema/Movie)

{:rdf/type :rdfs/Class,
 :rdfs/subClassOf :schema/CreativeWork,
 :mop/classPrecedenceList
 [:schema/Movie :schema/CreativeWork :schema/Thing :rdfs/Class],
 :rdfs/label "Movie",
 :rdfs/comment "A movie.",
 :mop/classDirectSlots
 #{:schema/director
   :schema/trailer
   :schema/productionCompany
   :schema/musicBy
   :schema/subtitleLanguage
   :schema/duration
   :schema/titleEIDR
   :schema/actors
   :schema/countryOfOrigin
   :schema/directors
   :schema/actor},
 :db/ident :schema/Movie}

(doc :schema/Movie)

;; -------------------------
;; :schema/Movie
;;    A movie.
;;   isa?
;;   :schema/CreativeWork
;;    :schema/Thing
;;      :rdfs/Class

Metaobject Protocol

Most methods within the system dispatch based on the :rdf/type of the object sorted by class precedence. This allows for dynamic method resolution typical in object-oriented systems but implemented through Clojure's multimethods.

The following describes an anonymous :owl/Class with no properties:

{:rdf/type :owl/Class}

;; Define a method that dispatches on the most specific :rdf/type of the object
(defmethod your-multimethod :your/Thing [args] ...)

datafy

Use clojure.datafy/datafy to find out what a metaobject means by providing a namespace qualified keyword to retrieve it from the currently bound environment (net.wikipunk.mop/*env*).

net.wikipunk.mop/env

The env variable holds the current environment in which metaobjects are resolved. It can be one of three values:

1. nil -- When nil, metaobjects are resolved in Clojure namespaces by looking up the namespace as a prefix in a registry and then looking up the name in that namespace.
2. Asami -- When Asami (net.wikipunk.asami.Connection) is bound to the environment metaobjects are resolved by looking the idents up using asami.core/entity.
3. Datomic -- When Datomic (net.wikipunk.datomic.Connection) is bound to the environment metaobjects are resolved by looking up the idents using datomic.client.api/pull.

credits

Aristotle

Semantic Web

rdfs:seeAlso

wikipunk.net

License

Copyright 2024 Adrian Medina

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.