diff --git a/headers/private/midi/protocol.h b/headers/private/midi/protocol.h
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+/**
+ * @file protocol.h
+ *
+ * Definitions for the communications protocol between 
+ * libmidi2.so and the midi_server.
+ *
+ * @author Matthijs Hollemans
+ */
+
+#ifndef MIDI_PROTOCOL_H
+#define MIDI_PROTOCOL_H
+
+/** MIME signature of the midi_server application. */
+#define MIDI_SERVER_SIGNATURE  "application/x-vnd.OpenBeOS.midi-server"
+
+/** Timeout for delivering and responding to messages (microseconds). */
+#define TIMEOUT  2000000
+
+/** Received when a new app starts using the Midi Kit. */
+#define MSG_REGISTER_APP  'Mapp'
+
+/** Sent when we have completed a "register app" request. */
+#define MSG_APP_REGISTERED  'mAPP'
+
+/** Received when an app creates a new local endpoint. */
+#define MSG_CREATE_ENDPOINT  'Mnew'
+
+/**
+ * Sent to all other applications when an app creates a 
+ * new endpoint. Also sent when an application registers 
+ * with the midi_server (MSG_REGISTER_APP). 
+ */
+#define MSG_ENDPOINT_CREATED  'mNEW'
+
+/** Received when an app deletes a local endpoint. */
+#define MSG_DELETE_ENDPOINT  'Mdel'
+
+/** 
+ * The midi_server sends this message to itself when an app 
+ * dies and its endpoints must be removed from the roster.
+ */
+#define MSG_PURGE_ENDPOINT  'Mdie'
+
+/**
+ * Sent to all applications when an endpoint is deleted,
+ * either by the app that owned it, or by the midi_server
+ * if the owner app has died.
+ */
+#define MSG_ENDPOINT_DELETED  'mDEL'
+
+/**
+ * Received when an app changes the attributes of one 
+ * of its local endpoints. 
+ */
+#define MSG_CHANGE_ENDPOINT  'Mchg'
+
+/** 
+ * Sent to all other applications when an app changes
+ * the attributes of one of its local endpoints.
+ */
+#define MSG_ENDPOINT_CHANGED  'mCHG'
+
+/**
+ * Received when an app wants to establish a connection
+ * between a producer and a consumer.
+ */
+#define MSG_CONNECT_ENDPOINTS  'Mcon'
+
+/** 
+ * Sent to all other applications when an app establishes
+ * a connection between a producer and a consumer. Like
+ * MSG_ENDPOINT_CREATED, this notification is also sent to
+ * applications when they register with the midi_server.
+ */
+#define MSG_ENDPOINTS_CONNECTED 'mCON'
+
+/**
+ * Received when an app wants to break a connection
+ * between a producer and a consumer.
+ */
+#define MSG_DISCONNECT_ENDPOINTS  'Mdis'
+
+/** 
+ * Sent to all other applications when an app breaks
+ * a connection between a producer and a consumer.
+ */
+#define MSG_ENDPOINTS_DISCONNECTED 'mDIS'
+
+#endif // MIDI_PROTOCOL_H