int plugin_register_data_set (const data_set_t *ds);
int plugin_register_log (const char *name,
plugin_log_cb callback, user_data_t *user_data);
int plugin_register_notification (const char *name,
int plugin_register_data_set (const data_set_t *ds);
int plugin_register_log (const char *name,
plugin_log_cb callback, user_data_t *user_data);
int plugin_register_notification (const char *name,