public CompletableFuture<Pair<Long, DeviceCommand>> sendSubscribeToUpdateRequest(final long commandId, final DeviceVO device, BiConsumer<DeviceCommand, Long> callback) { CompletableFuture<Pair<Long, DeviceCommand>> future = new CompletableFuture<>(); final Long subscriptionId = idGenerator.generate(); Consumer<Response> responseConsumer = response -> { Action resAction = response.getBody().getAction(); if (resAction.equals(Action.COMMAND_UPDATE_SUBSCRIBE_RESPONSE)) { future.complete(Pair.of(response.getBody().cast(CommandUpdateSubscribeResponse.class).getSubscriptionId(), response.getBody().cast(CommandUpdateSubscribeResponse.class).getDeviceCommand())); } else if (resAction.equals(COMMAND_UPDATE_EVENT)) { callback.accept(response.getBody().cast(CommandUpdateEvent.class).getDeviceCommand(), subscriptionId); } else { logger.warn("Unknown action received from backend {}", resAction); } }; Filter filter = new Filter(device.getNetworkId(), device.getDeviceTypeId(), Long.toString(commandId), COMMAND_UPDATE_EVENT.name(), null); rpcClient.call(Request.newBuilder() .withBody(new CommandUpdateSubscribeRequest(commandId, device.getDeviceId(), subscriptionId, filter)) .build(), responseConsumer); return future; }