+ session_error_t err, u32 opaque);
+int app_worker_add_half_open (app_worker_t * app_wrk, transport_proto_t tp,
+ session_handle_t ho_handle,
+ session_handle_t wrk_handle);
+int app_worker_del_half_open (app_worker_t * app_wrk, transport_proto_t tp,
+ session_handle_t ho_handle);
+u64 app_worker_lookup_half_open (app_worker_t * app_wrk, transport_proto_t tp,
+ session_handle_t ho_handle);