Add message extension.

11 files changed, 468 insertions, 41 deletions

diff --git a/doc/reference.doxygen.in b/doc/reference.doxygen.in
index 3e35029..16a35c4 100644
--- a/doc/reference.doxygen.in
+++ b/doc/reference.doxygen.in
@@ -576,6 +576,7 @@ INPUT =  \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/event/event.h \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/instance-access/instance-access.h \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/log/log.h \
+	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/message/message.h \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/osc/osc-print.h \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/osc/osc.h \
 	@LV2_SRCDIR@/lv2/lv2plug.in/ns/ext/pui/pui.h \
@@ -611,7 +612,7 @@ FILE_PATTERNS          =
 # should be searched for input files as well. Possible values are YES and NO. 
 # If left blank NO is used.
 
-RECURSIVE              = YES
+RECURSIVE              = NO
 
 # The EXCLUDE tag can be used to specify files and/or directories that should 
 # excluded from the INPUT source files. This way you can easily exclude a 
diff --git a/lv2/lv2plug.in/ns/ext/message/ext.pc.in b/lv2/lv2plug.in/ns/ext/message/ext.pc.in
new file mode 120000
index 0000000..03dd044
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/ext.pc.in
@@ -0,0 +1 @@
+../../../../../ext.pc.in
\ No newline at end of file
diff --git a/lv2/lv2plug.in/ns/ext/message/manifest.ttl b/lv2/lv2plug.in/ns/ext/message/manifest.ttl
new file mode 100644
index 0000000..3708bd9
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/manifest.ttl
@@ -0,0 +1,9 @@
+@prefix lv2:  <http://lv2plug.in/ns/lv2core#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+
+<http://lv2plug.in/ns/ext/message>
+	a lv2:Specification ;
+	lv2:minorVersion 0 ;
+	lv2:microVersion 1 ;
+	rdfs:seeAlso <message.ttl> .
+
diff --git a/lv2/lv2plug.in/ns/ext/message/message.h b/lv2/lv2plug.in/ns/ext/message/message.h
new file mode 100644
index 0000000..9c03713
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/message.h
@@ -0,0 +1,47 @@
+/*
+  Copyright 2012 David Robillard <http://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.
+*/
+
+/**
+   @file message.h C header for the LV2 Message extension
+   <http://lv2plug.in/ns/ext/message>.
+
+   The message extension is purely data, this header merely defines URIs
+   for convenience.
+*/
+
+#ifndef LV2_MESSAGE_H
+#define LV2_MESSAGE_H
+
+#define LV2_MESSAGE_URI "http://lv2plug.in/ns/ext/message"
+
+#define LV2_MESSAGE_Ack      LV2_MESSAGE_URI "#Ack"
+#define LV2_MESSAGE_Delete   LV2_MESSAGE_URI "#Delete"
+#define LV2_MESSAGE_Error    LV2_MESSAGE_URI "#Error"
+#define LV2_MESSAGE_Get      LV2_MESSAGE_URI "#Get"
+#define LV2_MESSAGE_Message  LV2_MESSAGE_URI "#Message"
+#define LV2_MESSAGE_Move     LV2_MESSAGE_URI "#Move"
+#define LV2_MESSAGE_Patch    LV2_MESSAGE_URI "#Patch"
+#define LV2_MESSAGE_Post     LV2_MESSAGE_URI "#Post"
+#define LV2_MESSAGE_Put      LV2_MESSAGE_URI "#Put"
+#define LV2_MESSAGE_Request  LV2_MESSAGE_URI "#Request"
+#define LV2_MESSAGE_Response LV2_MESSAGE_URI "#Response"
+#define LV2_MESSAGE_Set      LV2_MESSAGE_URI "#Set"
+
+#define LV2_MESSAGE_add   LV2_MESSAGE_URI "#add"
+#define LV2_MESSAGE_body  LV2_MESSAGE_URI "#body"
+#define LV2_MESSAGE_cause LV2_MESSAGE_URI "#cause"
+
+#endif  /* LV2_MESSAGE_H */
diff --git a/lv2/lv2plug.in/ns/ext/message/message.ttl b/lv2/lv2plug.in/ns/ext/message/message.ttl
new file mode 100644
index 0000000..a22dea3
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/message.ttl
@@ -0,0 +1,334 @@
+# LV2 Message 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 msg:  <http://lv2plug.in/ns/ext/message#> .
+@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/message>
+	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 Message" ;
+	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 message 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>
+""" .
+
+msg:Ack
+	a rdfs:Class ;
+	rdfs:subClassOf msg: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>
+""" .
+
+msg:Delete
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request ;
+	rdfs:label "Delete" ;
+	lv2:documentation """
+<p>Request the subject(s) be deleted.</p>
+""" .
+
+msg:Error
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Response ;
+    rdfs:label "Error" ;
+    lv2:documentation """
+<p>A response indicating an error processing a request.</p>
+""" .
+
+msg:Get
+	a rdfs:Class ;
+	rdfs:subClassOf msg: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 msg:subject property as the request, and
+a msg:body that is a description of that subject.  For example:</p>
+<pre class="turtle-code">
+&lt;get-request&gt;
+    a msg:Get ;
+    msg:subject &lt;something&gt; .
+</pre>
+
+<p>Could result in:</p>
+<pre class="turtle-code">
+[]
+    a msg:Response ;
+    msg:cause &lt;get-request&gt; ;
+    msg:subject &lt;something&gt; ;
+    msg:body [
+        eg:name "Something" ;
+        eg:ratio 1.6180339887 ;
+    ] .
+</pre>
+
+<p>Note the use of blank nodes is not required; the value of msg:body may be
+the actual resource node.  Depending on the transport and syntax used this may
+be preferable.  However, the msg: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 msg:Response ;
+    msg:cause &lt;get-request&gt; ;
+    msg:subject &lt;something&gt; ;
+    msg:body &lt;something&gt; .
+</pre>
+""" .
+
+msg:Insert
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request ;
+	rdfs:label "Insert" ;
+	rdfs:subClassOf [
+		a owl:Restriction ;
+		owl:maxCardinality 1 ;
+		owl:onProperty msg:subject
+	] ;
+	lv2:documentation """
+<p>Insert the msg:body at msg: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>
+""" .
+
+msg:Message
+	a rdfs:Class ;
+	rdfs:label "Message" .
+
+msg:Move
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request ;
+	rdfs:label "Move" ;
+	rdfs:subClassOf [
+		a owl:Restriction ;
+		owl:maxCardinality 1 ;
+		owl:onProperty msg:subject ;
+	] , [
+		a owl:Restriction ;
+		owl:cardinality 1 ;
+		owl:onProperty msg:destination ;
+	] ;
+	lv2:documentation """
+<p>Move the msg:subject to msg:destination.  After this, msg:destination has
+the description msg:subject had prior to this request's execution, and
+msg:subject does not exist any more.It is an error if the subject does not
+exist or the destination already exists.</p>
+""" .
+
+msg:Patch
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request , [
+		a owl:Restriction ;
+		owl:minCardinality 1 ;
+		owl:onProperty msg:subject
+	] , [
+		a owl:Restriction ;
+		owl:maxCardinality 1 ;
+		owl:onProperty msg:add
+	] , [
+		a owl:Restriction ;
+		owl:maxCardinality 1 ;
+		owl:onProperty msg:remove
+	] ;
+	lv2:documentation """
+<p>A method for modifying the properties of an object.</p>
+
+<p>This method always has at least one msg:subject, and exactly one msg:add
+and msg:remove property.  The value of msg:add and msg:remove are nodes
+which have the properties to add or remove from the subject(s), respectively.
+The special value msg: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 msg:Patch ;
+    msg:subject &lt;something&gt; ;
+    msg:add [
+        eg:name "New name" ;
+        eg:age 42 ;
+    ] ;
+    msg:remove [
+        eg:name "Old name" ;
+        eg:age msg:wildcard ;  # Remove all old eg:age properties
+    ] .
+</pre>
+""" .
+
+msg:Put
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request ;
+	rdfs:label "Put" ;
+	rdfs:subClassOf [
+		a owl:Restriction ;
+		owl:maxCardinality 1 ;
+		owl:onProperty msg:subject
+	] ;
+	lv2:documentation """
+<p>Put the msg:body as the msg:subject.  If the subject does not already exist,
+it is created.  If the subject does already exist, the msg:body is considered
+an updated version of it, and the previous version is replaced.</p>
+""" .
+
+msg:Request
+	a rdfs:Class ;
+	rdfs:label "Request" ;
+	rdfs:subClassOf msg:Message ;
+	lv2:documentation """
+<p>A request.  A request may have a msg: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>
+""" .
+
+msg:Response
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Message ;
+	rdfs:label "Response" ;
+	lv2:documentation """
+<p>A response to a method.</p>
+""" .
+
+msg:Set
+	a rdfs:Class ;
+	rdfs:subClassOf msg:Request , [
+		a owl:Restriction ;
+		owl:cardinality 1 ;
+		owl:onProperty msg:body
+	] ;
+	lv2:documentation """
+<p>A method for setting properties of an object to unique values.</p>
+
+<p>This is a simplified version of msg:Patch which only makes sense for
+properties which have at most one value.  This method always has at least one
+msg:subject, and exactly one msg:add property.  All the properties of the
+value of msg:add are set on the subject, with all old values for those
+properties removed.  For example:</p>
+
+<pre class="turtle-code">
+[]
+    a msg:Set ;
+    msg:subject &lt;something&gt; ;
+    msg:body [
+        eg:name "New name" ;
+        eg:age 42 ;
+    ] .
+</pre>
+
+<p>This method is equivalent to a msg:Patch where the msg:remove value has
+every property of msg:add but with wildcard values.  For example, the above
+message is equivalent to:</p>
+<pre class="turtle-code">
+[]
+    a msg:Patch ;
+    msg:subject &lt;something&gt; ;
+    msg:add [
+        eg:name "New name" ;
+        eg:age 42 ;
+    ] ;
+    msg:remove [
+        eg:name msg:wildcare ;
+        eg:age msg:wildcard ;
+    ] ;
+</pre>
+""" .
+
+msg:add
+	a rdf:Property ,
+		owl:ObjectProperty ;
+	rdfs:domain msg:Method .
+
+msg:body
+	a rdf:Property ,
+		owl:ObjectProperty ;
+	rdfs:domain msg: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>
+""" .
+
+msg:cause
+	a rdf:Property ,
+		owl:ObjectProperty ;
+	rdfs:domain msg:Response ;
+	rdfs:range msg:Request ;
+	lv2:documentation """
+<p>The request this is a response to.</p>
+""" .
\ No newline at end of file
diff --git a/lv2/lv2plug.in/ns/ext/message/waf b/lv2/lv2plug.in/ns/ext/message/waf
new file mode 120000
index 0000000..5235032
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/waf
@@ -0,0 +1 @@
+../../../../../waf
\ No newline at end of file
diff --git a/lv2/lv2plug.in/ns/ext/message/wscript b/lv2/lv2plug.in/ns/ext/message/wscript
new file mode 120000
index 0000000..7e2c01b
--- /dev/null
+++ b/lv2/lv2plug.in/ns/ext/message/wscript
@@ -0,0 +1 @@
+../../../../../ext.wscript
\ No newline at end of file
diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index ae5434a..5292aee 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -44,6 +44,7 @@
 #include <semaphore.h>
 
 #include "lv2/lv2plug.in/ns/ext/atom/atom-helpers.h"
+#include "lv2/lv2plug.in/ns/ext/message/message.h"
 #include "lv2/lv2plug.in/ns/ext/state/state.h"
 #include "lv2/lv2plug.in/ns/ext/urid/urid.h"
 #include "lv2/lv2plug.in/ns/lv2core/lv2.h"
@@ -81,11 +82,13 @@ typedef struct {
 
 	/* URIs */
 	struct {
+		LV2_URID atom_Blank;
+		LV2_URID atom_Resource;
+		LV2_URID filename_key;
 		LV2_URID midi_Event;
-		LV2_URID atom_Object;
-		LV2_URID set_message;
+		LV2_URID msg_Set;
+		LV2_URID msg_body;
 		LV2_URID state_Path;
-		LV2_URID filename_key;
 	} uris;
 
 	/* Playback state */
@@ -221,27 +224,27 @@ instantiate(const LV2_Descriptor*     descriptor,
 	}
 
 	/* Scan host features for URID map */
+	LV2_URID_Map* map = NULL;
 	for (int i = 0; features[i]; ++i) {
 		if (!strcmp(features[i]->URI, LV2_URID_URI "#map")) {
-			plugin->map = (LV2_URID_Map*)features[i]->data;
-			plugin->uris.midi_Event = plugin->map->map(
-				plugin->map->handle, MIDI_EVENT_URI);
-			plugin->uris.atom_Object = plugin->map->map(
-				plugin->map->handle, ATOM_OBJECT_URI);
-			plugin->uris.set_message = plugin->map->map(
-				plugin->map->handle, SET_MESSAGE_URI);
-			plugin->uris.state_Path = plugin->map->map(
-				plugin->map->handle, LV2_STATE_PATH_URI);
-			plugin->uris.filename_key = plugin->map->map(
-				plugin->map->handle, FILENAME_URI);
+			map = (LV2_URID_Map*)features[i]->data;
 		}
 	}
 
-	if (!plugin->map) {
+	if (!map) {
 		fprintf(stderr, "Host does not support urid:map.\n");
 		goto fail;
 	}
 
+	plugin->map                = map;
+	plugin->uris.atom_Blank    = map->map(map->handle, ATOM_BLANK_URI);
+	plugin->uris.atom_Resource = map->map(map->handle, ATOM_RESOURCE_URI);
+	plugin->uris.filename_key  = map->map(map->handle, FILENAME_URI);
+	plugin->uris.midi_Event    = map->map(map->handle, MIDI_EVENT_URI);
+	plugin->uris.msg_Set       = map->map(map->handle, LV2_MESSAGE_Set);
+	plugin->uris.msg_body      = map->map(map->handle, LV2_MESSAGE_body);
+	plugin->uris.state_Path    = map->map(map->handle, LV2_STATE_PATH_URI);
+
 	/* Open the default sample file */
 	strncpy(plugin->pending_samp->filepath, path, STRING_BUF);
 	strncat(plugin->pending_samp->filepath,
@@ -275,28 +278,41 @@ run(LV2_Handle instance,
 				plugin->frame = 0;
 				plugin->play  = true;
 			}
-		} else if (ev->body.type == plugin->uris.atom_Object) {
+		} else if (ev->body.type == plugin->uris.atom_Resource
+		           || ev->body.type == plugin->uris.atom_Blank) {
 			const LV2_Atom_Object* obj = (LV2_Atom_Object*)&ev->body;
-			if (obj->type == plugin->uris.set_message) {
+			if (obj->type == plugin->uris.msg_Set) {
+				const LV2_Atom_Object* body = NULL;
+				LV2_Atom_Object_Query q1[] = {
+					{ plugin->uris.msg_body, (const LV2_Atom**)&body },
+					LV2_OBJECT_QUERY_END
+				};
+				lv2_object_get(obj, q1);
+
+				if (!body) {  // TODO: check type
+					fprintf(stderr, "Malformed set message with no body.\n");
+					continue;
+				}
+						
 				const LV2_Atom* filename = NULL;
-				LV2_Atom_Object_Query q[] = {
+				LV2_Atom_Object_Query q2[] = {
 					{ plugin->uris.filename_key, &filename },
 					LV2_OBJECT_QUERY_END
 				};
-				lv2_object_get(obj, q);
-
-				if (filename) {
-					char* str = (char*)LV2_ATOM_BODY(filename);
-					fprintf(stderr, "Request to load %s\n", str);
-					memcpy(plugin->pending_samp->filepath, str, filename->size);
-					sem_post(&plugin->signal);
-				} else {
+				lv2_object_get((LV2_Atom_Object*)body, q2);
+
+				if (!filename) {
 					fprintf(stderr, "Ignored set message with no filename\n");
+					continue;
 				}
+
+				char* str = (char*)LV2_ATOM_BODY(filename);
+				fprintf(stderr, "Request to load %s\n", str);
+				memcpy(plugin->pending_samp->filepath, str, filename->size);
+				sem_post(&plugin->signal);
 			} else {
 				fprintf(stderr, "Unknown message type %d\n", obj->id);
 			}
-
 		} else {
 			fprintf(stderr, "Unknown event type %d\n", ev->body.type);
 		}
diff --git a/plugins/eg-sampler.lv2/sampler_ui.c b/plugins/eg-sampler.lv2/sampler_ui.c
index ea57cc1..b807be9 100644
--- a/plugins/eg-sampler.lv2/sampler_ui.c
+++ b/plugins/eg-sampler.lv2/sampler_ui.c
@@ -26,6 +26,7 @@
 #include "lv2/lv2plug.in/ns/ext/atom/atom-helpers.h"
 #include "lv2/lv2plug.in/ns/ext/atom/atom.h"
 #include "lv2/lv2plug.in/ns/ext/atom/forge.h"
+#include "lv2/lv2plug.in/ns/ext/message/message.h"
 #include "lv2/lv2plug.in/ns/ext/urid/urid.h"
 #include "lv2/lv2plug.in/ns/extensions/ui/ui.h"
 
@@ -77,15 +78,29 @@ on_load_clicked(GtkWidget* widget,
 	uint8_t obj_buf[OBJ_BUF_SIZE];
 	lv2_atom_forge_set_buffer(&ui->forge, obj_buf, OBJ_BUF_SIZE);
 
-	LV2_Atom* obj = (LV2_Atom*)lv2_atom_forge_object(
-		&ui->forge, NULL, 0, uri_to_id(ui, SET_MESSAGE_URI));
-	lv2_atom_forge_property_head(&ui->forge, obj,
+	/* Send [
+	 *     a msg:Set ;
+	 *     msg:body [
+	 *         eg-sampler:filename "/foo/bar.wav" ;
+	 *     ] ;
+	 * ]
+	 */
+	LV2_Atom* set = (LV2_Atom*)lv2_atom_forge_blank(
+		&ui->forge, NULL, 0, uri_to_id(ui, LV2_MESSAGE_Set));
+	lv2_atom_forge_property_head(&ui->forge, set,
+	                             uri_to_id(ui, LV2_MESSAGE_body), 0);
+	LV2_Atom* body = (LV2_Atom*)lv2_atom_forge_blank(&ui->forge, set, 0, 0);
+	lv2_atom_forge_property_head(&ui->forge, body,
 	                             uri_to_id(ui, FILENAME_URI), 0);
-	lv2_atom_forge_string(&ui->forge, obj, (uint8_t*)filename, filename_len);
+	lv2_atom_forge_string(&ui->forge, set, (uint8_t*)filename, filename_len);
 
-	ui->write(ui->controller, 0, sizeof(LV2_Atom) + obj->size,
+	lv2_atom_forge_property_head(&ui->forge, body,
+	                             uri_to_id(ui, LV2_MESSAGE_body), 0);
+	set->size += body->size;
+
+	ui->write(ui->controller, 0, sizeof(LV2_Atom) + set->size,
 	          uri_to_id(ui, NS_ATOM "atomTransfer"),
-	          obj);
+	          set);
 
 	g_free(filename);
 }
diff --git a/plugins/eg-sampler.lv2/uris.h b/plugins/eg-sampler.lv2/uris.h
index 5e968ed..87b16cc 100644
--- a/plugins/eg-sampler.lv2/uris.h
+++ b/plugins/eg-sampler.lv2/uris.h
@@ -18,8 +18,8 @@
 #define NS_ATOM "http://lv2plug.in/ns/ext/atom#"
 #define NS_RDF  "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 
-#define SAMPLER_URI     "http://lv2plug.in/plugins/eg-sampler"
-#define MIDI_EVENT_URI  "http://lv2plug.in/ns/ext/midi#MidiEvent"
-#define FILENAME_URI    SAMPLER_URI "#filename"
-#define ATOM_OBJECT_URI NS_ATOM "Object"
-#define SET_MESSAGE_URI "http: //example.org/set"
+#define SAMPLER_URI       "http://lv2plug.in/plugins/eg-sampler"
+#define MIDI_EVENT_URI    "http://lv2plug.in/ns/ext/midi#MidiEvent"
+#define FILENAME_URI      SAMPLER_URI "#filename"
+#define ATOM_BLANK_URI    NS_ATOM "Blank"
+#define ATOM_RESOURCE_URI NS_ATOM "Resource"
diff --git a/plugins/eg-sampler.lv2/wscript b/plugins/eg-sampler.lv2/wscript
index 8050e72..e5988ed 100644
--- a/plugins/eg-sampler.lv2/wscript
+++ b/plugins/eg-sampler.lv2/wscript
@@ -30,6 +30,8 @@ def configure(conf):
                           uselib_store='LV2_ATOM')
         autowaf.check_pkg(conf, 'lv2-lv2plug.in-ns-ext-state',
                           uselib_store='LV2_STATE')
+        autowaf.check_pkg(conf, 'lv2-lv2plug.in-ns-ext-message',
+                          uselib_store='LV2_MESSAGE')
 
     autowaf.check_pkg(conf, 'sndfile', uselib_store='SNDFILE',
                       atleast_version='1.0.0', mandatory=True)
@@ -76,7 +78,7 @@ def build(bld):
               name         = 'sampler',
               target       = '%s/sampler' % bundle,
               install_path = '${LV2DIR}/%s' % bundle,
-              use          = 'SNDFILE',
+              use          = 'SNDFILE LV2CORE LV2_URID LV2_ATOM LV2_STATE LV2_MESSAGE',
               includes     = includes)
 
     # Build UI library
@@ -87,6 +89,6 @@ def build(bld):
                   name         = 'sampler_ui',
                   target       = '%s/sampler_ui' % bundle,
                   install_path = '${LV2DIR}/%s' % bundle,
-                  use          = 'GTK2',
+                  use          = 'GTK2 LV2CORE LV2_URID LV2_ATOM LV2_STATE LV2_MESSAGE',
                   includes     = includes)