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# LV2 Patch Extension
# Copyright 2012 David Robillard <d@drobilla.net>
#
# 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.
#
# THIS 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.

@prefix doap:  <http://usefulinc.com/ns/doap#> .
@prefix foaf:  <http://xmlns.com/foaf/0.1/> .
@prefix lv2:   <http://lv2plug.in/ns/lv2core#> .
@prefix patch: <http://lv2plug.in/ns/ext/patch#> .
@prefix owl:   <http://www.w3.org/2002/07/owl#> .
@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#> .

<http://lv2plug.in/ns/ext/patch>
	a lv2:Specification ;
	doap:license <http://opensource.org/licenses/isc> ;
	doap:maintainer [
		a foaf:Person ;
		rdfs:seeAlso <http://drobilla.net/drobilla.rdf> ;
		foaf:homepage <http://drobilla.net/> ;
		foaf:name "David Robillard" ;
	] ;
	doap:name "LV2 Patch" ;
	doap:release [
		doap:created "2012-02-08" ;
		doap:revision "0.1" ;
	] ;
	doap:shortdesc "Messages for accessing and manipulating properties." ;
	lv2:documentation """
<p>This extension defines messages which can be used to access and manipulate
property-based data.  It is designed to provide a powerful dynamic control
interface for LV2 plugins, but is useful for RDF-like systems in general.</p>

<p>The main feature of this design is that requests and responses are
themselves completely described in RDF.  Thus, the complete <q>protocol</q> can
be expressed wherever RDF can without imposing additional implementation
burdens like a new syntax or binary formats.  In particular, messages can be
serialised in Turtle, or as an <a
href="http://lv2plug.in/ns/ext/atom#Object">LV2 Object</a>.</p>

<p>This set of patch types is deliberately small to avoid an explosion of
messages that all implementations would have to explicitly support.  Instead,
the idea is to achieve control via manipulating properties rather than defining
custom commands.  However, this is conceptual; there is no requirement that the
receiver actually implement a store of resources with properties.</p>

<p>For example, consider an object that can blink.  Rather than define a
specific interface to control this (e.g. <code>obj.start_blinking();
obj.stop_blinking()</code>), set a <q>blinking</q> property to true or false to
achieve the desired behaviour.  One benefit of this approach is that a
persistent state model is available <q>for free</q>: simply serialise the
<q>blinking</q> property.</p>

<p>Because changes are described in terms of properties, important
functionality like undo stacks or revision control are simple to implement
generically.  Accordingly, plugins are strongly encouraged to use these
property-based messages rather than defining custom methods for every action
they require (or worse, defining entirely new formats for messages).</p>

<p>These methods are deliberately very similar to HTTP methods, but defined
specifically for property-based resources.  The <q>properties</q> used here are
RDF properties, thus predicates from any of the countless pre-existing
vocabularies may be used.</p>
""" .

patch:Ack
	a rdfs:Class ;
	rdfs:subClassOf patch:Response ;
	rdfs:label "Ack" ;
	lv2:documentation """
<p>An acknowledgement that a request has been successfully processed.  This is
returned as a reply when a specific reply type is not necessary or
appropriate.</p>
""" .

patch:Delete
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ;
	rdfs:label "Delete" ;
	lv2:documentation """
<p>Request the subject(s) be deleted.</p>
""" .

patch:Error
	a rdfs:Class ;
	rdfs:subClassOf patch:Response ;
	rdfs:label "Error" ;
	lv2:documentation """
<p>A response indicating an error processing a request.</p>
""" .

patch:Get
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ;
	rdfs:label "Get" ;
	lv2:documentation """
<p>Request a description of the subject.</p>

<p>The detail of the response is not specified, it may be a flat description of
all the properties of the subject, or a more expressive description with
several subjects.  A good choice is a <q><a
href="http://www.w3.org/Submission/CBD/">concise bounded description</a></q>,
i.e. a description which recursively includes all properties with blank node
values.</p>

<p>The response should have the same patch:subject property as the request, and
a patch:body that is a description of that subject.  For example:</p>
<pre class="turtle-code">
&lt;get-request&gt;
    a patch:Get ;
    patch:subject &lt;something&gt; .
</pre>

<p>Could result in:</p>
<pre class="turtle-code">
[]
    a patch:Response ;
    patch:request &lt;get-request&gt; ;
    patch:subject &lt;something&gt; ;
    patch:body [
        eg:name "Something" ;
        eg:ratio 1.6180339887 ;
    ] .
</pre>

<p>Note the use of blank nodes is not required; the value of patch:body may be
the actual resource node.  Depending on the transport and syntax used this may
be preferable.  However, the patch:subject property is required regardless.  For
example, the same response could be written:</p>

<pre class="turtle-code">
&lt;something&gt;
    eg:name "Something" ;
    eg:ratio 1.6180339887 .

[]
    a patch:Response ;
    patch:request &lt;get-request&gt; ;
    patch:subject &lt;something&gt; ;
    patch:body &lt;something&gt; .
</pre>
""" .

patch:Insert
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ;
	rdfs:label "Insert" ;
	rdfs:subClassOf [
		a owl:Restriction ;
		owl:maxCardinality 1 ;
		owl:onProperty patch:subject ;
	] ;
	lv2:documentation """
<p>Insert the patch:body at patch:subject.  If the subject does not exist, it is
created.  If the subject does already exist, it is added to.  This request only
adds properties, it never removes them.  The user must take care that multiple
values are not set for properties which should only have one value.</p>
""" .

patch:Message
	a rdfs:Class ;
	rdfs:label "Message" .

patch:Move
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ;
	rdfs:label "Move" ;
	rdfs:subClassOf [
		a owl:Restriction ;
		owl:maxCardinality 1 ;
		owl:onProperty patch:subject ;
	] , [
		a owl:Restriction ;
		owl:cardinality 1 ;
		owl:onProperty patch:destination ;
	] ;
	lv2:documentation """
<p>Move the patch:subject to patch:destination.  After this, patch:destination has
the description patch:subject had prior to this request's execution, and
patch:subject does not exist any more.It is an error if the subject does not
exist or the destination already exists.</p>
""" .

patch:Patch
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ,
	[
		a owl:Restriction ;
		owl:minCardinality 1 ;
		owl:onProperty patch:subject ;
	] , [
		a owl:Restriction ;
		owl:maxCardinality 1 ;
		owl:onProperty patch:add ;
	] , [
		a owl:Restriction ;
		owl:maxCardinality 1 ;
		owl:onProperty patch:remove ;
	] ;
	lv2:documentation """
<p>A method for modifying the properties of an object.</p>

<p>This method always has at least one patch:subject, and exactly one patch:add
and patch:remove property.  The value of patch:add and patch:remove are nodes
which have the properties to add or remove from the subject(s), respectively.
The special value patch:wildcard may be used as the value of a remove property
to remove all properties with the given predicate.  For example:</p>

<pre class="turtle-code">
[]
    a patch:Patch ;
    patch:subject &lt;something&gt; ;
    patch:add [
        eg:name "New name" ;
        eg:age 42 ;
    ] ;
    patch:remove [
        eg:name "Old name" ;
        eg:age patch:wildcard ;  # Remove all old eg:age properties
    ] .
</pre>
""" .

patch:Put
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ;
	rdfs:label "Put" ;
	rdfs:subClassOf [
		a owl:Restriction ;
		owl:maxCardinality 1 ;
		owl:onProperty patch:subject ;
	] ;
	lv2:documentation """
<p>Put the patch:body as the patch:subject.  If the subject does not already exist,
it is created.  If the subject does already exist, the patch:body is considered
an updated version of it, and the previous version is replaced.</p>
""" .

patch:Request
	a rdfs:Class ;
	rdfs:label "Request" ;
	rdfs:subClassOf patch:Message ;
	lv2:documentation """
<p>A request.  A request may have a patch:subject property, which indicates which
resource the request applies to.  The subject may be omitted in contexts where
it is implicit (e.g. the recipient is the subject).</p>
""" .

patch:Response
	a rdfs:Class ;
	rdfs:subClassOf patch:Message ;
	rdfs:label "Response" ;
	lv2:documentation """
<p>A response to a method.</p>
""" .

patch:Set
	a rdfs:Class ;
	rdfs:subClassOf patch:Request ,
	[
		a owl:Restriction ;
		owl:cardinality 1 ;
		owl:onProperty patch:body ;
	] ;
	lv2:documentation """
<p>A method for setting properties of an object to unique values.</p>

<p>This is a simplified version of patch:Patch which only makes sense for
properties which have at most one value.  This method always has at least one
patch:subject, and exactly one patch:add property.  All the properties of the
value of patch:add are set on the subject, with all old values for those
properties removed.  For example:</p>

<pre class="turtle-code">
[]
    a patch:Set ;
    patch:subject &lt;something&gt; ;
    patch:body [
        eg:name "New name" ;
        eg:age 42 ;
    ] .
</pre>

<p>This method is equivalent to a patch:Patch where the patch:remove value has
every property of patch:add but with wildcard values.  For example, the above
patch is equivalent to:</p>
<pre class="turtle-code">
[]
    a patch:Patch ;
    patch:subject &lt;something&gt; ;
    patch:add [
        eg:name "New name" ;
        eg:age 42 ;
    ] ;
    patch:remove [
        eg:name patch:wildcare ;
        eg:age patch:wildcard ;
    ] ;
</pre>
""" .

patch:subject
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Message .

patch:add
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Message .

patch:remove
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Message .

patch:destination
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Message .

patch:body
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Message ;
	lv2:documentation """
<p>The body of a message.</p>

<p>The details of this property's value depend on the type of message it is a
part of.</p>
""" .

patch:request
	a rdf:Property ,
		owl:ObjectProperty ;
	rdfs:domain patch:Response ;
	rdfs:range patch:Request ;
	lv2:documentation """
<p>The request this is a response to.</p>
""" .