- void (*call)(void *closure, const char *api, const char *verb, struct json_object *args, void (*callback)(void*, int, struct json_object*), void *callback_closure);
+ /* CAUTION: respect the order, add at the end */
+
+ void (*call)(void *closure, const char *api, const char *verb, struct json_object *args,
+ void (*callback)(void*, int, struct json_object*), void *callback_closure);
+
+ int (*call_sync)(void *closure, const char *api, const char *verb, struct json_object *args,
+ struct json_object **result);