grpc_invoke_async_np - Executes an RPC.
  grpc_error_t grpc_invoke_async_np(
                   grpc_object_handle_t_np *handle,
                   char *method_name,
                   grpc_sessionid_t *session_id,
                   ...)
  grpc_object_handle_t_np *handle  char *method_name  grpc_sessionid_t *session_id  Other argumentsThe grpc_invoke_async_np() function calls the method defined by the object handle. The grpc_invoke_async_np() function does not wait for the called method to complete execution.
This function is MT-safe.
If successful, GRPC_NO_ERROR is returned. In the case of an error, Error code is returned.
  GRPC_NOT_INITIALIZED  GRPC_SERVER_NOT_FOUND  GRPC_FUNCTION_NOT_FOUND  GRPC_INVALID_FUNCTION_HANDLE  GRPC_RPC_REFUSED  GRPC_COMMUNICATION_FAILED  GRPC_TIMEOUT_NP  GRPC_OTHER_ERROR_CODE