int varlink_invoke(Varlink *v, const char *method, JsonVariant *parameters);
int varlink_invokeb(Varlink *v, const char *method, ...);
+/* Enqueue method call, expect a reply now, and possibly more later, which are all delivered to the reply callback */
+int varlink_observe(Varlink *v, const char *method, JsonVariant *parameters);
+int varlink_observeb(Varlink *v, const char *method, ...);
+
/* Enqueue a final reply */
int varlink_reply(Varlink *v, JsonVariant *parameters);
int varlink_replyb(Varlink *v, ...);