+struct user_data_s
+{
+ void *data;
+ void (*free_func) (void *);
+};
+typedef struct user_data_s user_data_t;
+
+/*
+ * Callback types
+ */
+typedef int (*plugin_init_cb) (void);
+typedef int (*plugin_read_cb) (user_data_t *);
+typedef int (*plugin_write_cb) (const data_set_t *, const value_list_t *,
+ user_data_t *);
+typedef int (*plugin_flush_cb) (int timeout, const char *identifier,
+ user_data_t *);
+typedef void (*plugin_log_cb) (int severity, const char *message,
+ user_data_t *);
+typedef int (*plugin_shutdown_cb) (void);
+typedef int (*plugin_notification_cb) (const notification_t *,
+ user_data_t *);
+