# LV2 Variables Extension
# Copyright (C) 2008 David Robillard
# 
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@prefix var:  <http://lv2plug.in/ns/ext/instance-var#> .
@prefix lv2:  <http://lv2plug.in/ns/lv2core#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema> .
@prefix doap: <http://usefulinc.com/ns/doap#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .

<http://lv2plug.in/ns/ext/instance-var> a lv2:Specification ;
    doap:license <http://usefulinc.com/doap/licenses/mit> ;
    doap:name "LV2 Instance Variables" ;
    doap:created "2008-08-18" ;
    doap:maintainer [
        a foaf:Person ;
        foaf:name "David Robillard" ;
        foaf:homepage <http://drobilla.net/> ;
        rdfs:seeAlso <http://drobilla.net/drobilla.rdf>
	] ;
	rdfs:comment """
An extension for setting named/typed variables on an instance of an
LV2 Plugin (or anything else).  A "variable" is really just a (reified)
RDF statement with an implicit subject (e.g. the plugin instance).

Variables serve as a portable, network transparent, and serialisable
mechanism for clients (e.g. user interfaces, programs) to control any
parameter of a running plugin instance.  Because variables are 'keyed'
by URI (the predicate), future extensions can define variables with
specific meanings or restricted/extended types.
The value (rdf:value) of a variable may be anything, but hosts or plugins
aren't guaranteed to support anything other than simple typed literals.
Serialisation and code access to complex variables is considered outside
the scope of this extension.

Hosts and plugins SHOULD use the following types for appropriate values:

<table>
<tr><th>RDF Type</th><th>Data Type</th></tr>
<tr><td>xsd:string</td><td>string</td></tr>
<tr><td>xsd:decimal</td><td>floating point number</td></tr>
<tr><td>xsd:integer</td><td>integer number</td></tr>
<tr><td>xsd:boolean</td><td>boolean value</td></tr>
</table>

This extension does not currently define a code mechanism for access
to variables.  A future revision, or a different extension, may.

An example of a plugin with several variables:
<pre>
&lt;http://example.org/plugin&gt; a lv2:Plugin ;
	lv2var:variable [
		rdf:predicate &lt;http://example.org/greetingology#Greeting&gt; ;
		rdf:value "Hello, cruel world."
	] , [
		rdf:predicate &lt;http://example.org/matheybits#Coeff&gt; ;
		rdf:value 1.23456
	] , [
		rdf:predicate &lt;http://example.org/databits#BigValue&gt; ;
		rdf:value [
			a somext:Something ;
			someext:foo "Foo?" ;
			someext:bar "Bar." ;
			someext:baz 1234.0
		]
	] .
</pre>
""" .


var:Variable a rdfs:Class ;
	rdfs:label   "LV2 Variable" ;
	rdfs:comment "A typed instance variable." ;

	rdfs:subClassOf [
		a                 owl:Restriction ;
		rdfs:comment      "Must have exactly one rdf:predicate which is a resource" ;
		owl:onProperty    rdf:predicate ;
		owl:cardinality   1 ;
		owl:allValuesFrom rdfs:Resource
	], [
		a                 owl:Restriction ;
		rdfs:comment      "Must have exactly one rdf:value (of any type)" ;
		owl:onProperty    rdf:value ;
		owl:cardinality   1
	] .


var:variable a owl:ObjectProperty ;
	rdfs:label   "Has a Variable" ;
	rdfs:range   var:Variable ;
	rdfs:comment """
Relates an LV2 Variable to some Resource, usually a plugin instance.
The domain of this property is not restricted, it may be used for anything.
The range is implicitly an lv2var:Variable, the 'a lv2var:Variable' triple
is not mandatory.
""" .