Add metadata.h file

common/jack/metadata.h

@@ -0,0 +1,222 @@
+/*
+  Copyright (C) 2011 David Robillard
+  Copyright (C) 2013 Paul Davis
+
+  This program is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or (at
+  your option) any later version.
+
+  This program is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+  License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with this program; if not, write to the Free Software Foundation,
+  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file   jack/metadata.h
+ * @ingroup publicheader
+ * @brief  JACK Metadata API
+ *
+ */
+
+#ifndef __jack_metadata_h__
+#define __jack_metadata_h__
+
+#include <jack/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup Metadata Metadata API.
+ * @{
+ */
+
+/**
+ * A single property (key:value pair).
+ */
+typedef struct {
+    /** The key of this property (URI string). */
+    const char* key;
+
+    /** The property value (null-terminated string). */
+    const char* data;
+
+    /**
+     * Type of data, either a MIME type or URI.
+     *
+     * If type is NULL or empty, the data is assumed to be a UTF-8 encoded
+     * string (text/plain). The data is a null-terminated string regardless of
+     * type, so values can always be copied, but clients should not try to
+     * interpret values of an unknown type.
+     *
+     * Example values:
+     * - image/png;base64 (base64 encoded PNG image)
+     * - http://www.w3.org/2001/XMLSchema#int (integer)
+     *
+     * Official types are preferred, but clients may use any syntactically
+     * valid MIME type (which start with a type and slash, like "text/...").
+     * If a URI type is used, it must be a complete absolute URI
+     * (which start with a scheme and colon, like "http:").
+     */
+    const char* type;
+} jack_property_t;
+
+/**
+ * Set a property on @p subject.
+ *
+ * See the above documentation for rules about @p subject and @p key.
+ * @param subject The subject to set the property on.
+ * @param key The key of the property.
+ * @param value The value of the property.
+ * @param type The type of the property. See the discussion of
+ *             types in the definition of jack_property_t above.
+ * @return 0 on success.
+ */
+int
+jack_set_property(jack_client_t*,
+                  jack_uuid_t subject,
+                  const char* key,
+                  const char* value,
+                  const char* type);
+
+/**
+ * Get a property on @p subject.
+ *
+ * @param subject The subject to get the property from.
+ * @param key The key of the property.
+ * @param value Set to the value of the property if found, or NULL otherwise.
+ *              The caller must free this value with jack_free().
+ * @param type The type of the property if set, or NULL. See the discussion
+ *             of types in the definition of jack_property_t above.
+ *             If non-null, the caller must free this value with jack_free().
+ *
+ * @return 0 on success, -1 if the @p subject has no @p key property.
+ */
+int
+jack_get_property(jack_uuid_t subject,
+                  const char* key,
+                  char**      value,
+                  char**      type);
+
+/**
+ * A description of a subject (a set of properties).
+ */
+typedef struct {
+    jack_uuid_t      subject;        /**< Subject being described. */
+    uint32_t         property_cnt;   /**< Number of elements in "properties". */
+    jack_property_t* properties;     /**< Array of properties. */
+    uint32_t         property_size;  /**< Private, do not use. */
+} jack_description_t;
+
+/**
+ * Free a description.
+ *
+ * @param desc a jack_description_t whose associated memory will all be released
+ * @param free_description_itself if non-zero, then @param desc will also be passed to free()
+ */
+void
+jack_free_description (jack_description_t* desc, int free_description_itself);
+
+/**
+ * Get a description of @p subject.
+ * @param subject The subject to get all properties of.
+ * @param desc Set to the description of subject if found, or NULL otherwise.
+ *             The caller must free this value with jack_free_description().
+ * @return 0 on success, -1 if no @p subject with any properties exists.
+ */
+int
+jack_get_properties (jack_uuid_t         subject,
+                     jack_description_t* desc);
+
+/**
+ * Get descriptions for all subjects with metadata.
+ * @param descs Set to a NULL-terminated array of descriptions.
+ *              The caller must free each of these with jack_free_description(),
+ *              and the array itself with jack_free().
+ * @return 0 on success.
+ */
+int
+jack_get_all_properties (jack_description_t** descs);
+
+/**
+ * Remove a single property on a subject.
+ *
+ * @param client The JACK client making the request to remove the property.
+ * @param subject The subject to remove the property from.
+ * @param key The key of the property to be removed.
+ *
+ * @return 0 on success, -1 otherwise
+ */
+int jack_remove_property (jack_client_t* client, jack_uuid_t subject, const char* key);
+
+/**
+ * Remove all properties on a subject.
+ *
+ * @param client The JACK client making the request to remove some properties.
+ * @param subject The subject to remove all properties from.
+ *
+ * @return a count of the number of properties removed, or -1 on error.
+ */
+int jack_remove_properties (jack_client_t* client, jack_uuid_t subject);
+
+/**
+ * Remove all properties.
+ *
+ * WARNING!! This deletes all metadata managed by a running JACK server.
+ * Data lost cannot be recovered (though it can be recreated by new calls
+ * to jack_set_property()).
+ *
+ * @param client The JACK client making the request to remove all properties
+ *
+ * @return 0 on success, -1 otherwise
+ */
+int jack_remove_all_properties (jack_client_t* client);
+
+typedef enum {
+        PropertyCreated,
+        PropertyChanged,
+        PropertyDeleted
+} jack_property_change_t;
+
+typedef void (*JackPropertyChangeCallback)(jack_uuid_t            subject,
+                                           const char*            key,
+                                           jack_property_change_t change,
+                                           void*                  arg);
+
+/**
+ * Arrange for @p client to call @p callback whenever a property is created,
+ * changed or deleted.
+ *
+ * @param client the JACK client making the request
+ * @param callback the function to be invoked when a property change occurs
+ * @param arg the argument to be passed to @param callback when it is invoked
+ *
+ * @return 0 success, -1 otherwise.
+ */
+int jack_set_property_change_callback (jack_client_t*             client,
+                                       JackPropertyChangeCallback callback,
+                                       void*                      arg);
+
+#ifdef __cplusplus
+} /* namespace */
+#endif
+
+/**
+ * @}
+ */
+
+extern const char* JACK_METADATA_PRETTY_NAME;
+extern const char* JACK_METADATA_HARDWARE;
+extern const char* JACK_METADATA_CONNECTED;
+extern const char* JACK_METADATA_PORT_GROUP;
+extern const char* JACK_METADATA_ICON_SMALL;
+extern const char* JACK_METADATA_ICON_LARGE;
+
+#endif  /* __jack_metadata_h__ */