如何在Windows UWP App中正确订阅蓝牙低能耗设备的GattCharacteristic.ValueChanged通知（指示）？

Question

在我的Linux机器上，我已经使用Java， TinyB库和BlueZ成功订阅了Timeular / ZEI蓝牙LE设备。

但是我确实需要Windows 10（1709）的相同功能。 我在Visual Studio 2017中使用最新的Windows SDK。

我的目标是订阅GattCharacteristic.ValueChanged事件，因此无论何时有人“掷骰子”，BTLE设备都会向Windows应用程序发送通知并调用我的DiceOrientationChangeHandler 。

到目前为止，我得到的是：

    const string DEVICE_MAC_ADDRESS = "ee:ab:17:be:37:20"; //Timeular's MAC address
    const string BLUETOOTH_LE_SERVICE_UUID = "c7e70010-c847-11e6-8175-8c89a55d403c"; //the service which contains Timeular's orientation change characteristic
    const string BLUETOOTH_LE_CHARACTERISTIC_UUID = "c7e70012-c847-11e6-8175-8c89a55d403c"; //the characteristic that allows subscription to notification (indication) for orientation change


    public async void SubscribeToOrientationChangeNotification()
    {
        BluetoothLEDevice bluetoothLEDevice = null;

        //loop through bluetooth devices until we found our desired device by mac address
        DeviceInformationCollection deviceInformationCollection = await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector());
        foreach (var deviceInformation in deviceInformationCollection)
        {
            String deviceInformationId = deviceInformation.Id;
            String mac = deviceInformationId.Substring(deviceInformationId.Length - 17);
            if (mac.Equals(DEVICE_MAC_ADDRESS))
            {
                bluetoothLEDevice = await BluetoothLEDevice.FromIdAsync(deviceInformation.Id);
                Debug.WriteLine($"Found Bluetooth LE Device [{mac}]: {bluetoothLEDevice.ConnectionStatus}");
                break;
            }
        }

        //Subscribe to the connection status change event
        bluetoothLEDevice.ConnectionStatusChanged += ConnectionStatusChangeHandler;

        //get the desired service
        Guid serviceGuid = Guid.Parse(BLUETOOTH_LE_SERVICE_UUID);
        GattDeviceServicesResult serviceResult = await bluetoothLEDevice.GetGattServicesForUuidAsync(serviceGuid);
        if (serviceResult.Status == GattCommunicationStatus.Success)
        {
            GattDeviceService service = serviceResult.Services[0];
            Debug.WriteLine($"Service @ {service.Uuid}, found and accessed!");

            //get the desired characteristic
            Guid characteristicGuid = Guid.Parse(BLUETOOTH_LE_CHARACTERISTIC_UUID);
            GattCharacteristicsResult characteristicResult = await service.GetCharacteristicsForUuidAsync(characteristicGuid);
            if (characteristicResult.Status == GattCommunicationStatus.Success)
            {
                GattCharacteristic characteristic = characteristicResult.Characteristics[0];
                Debug.WriteLine($"Characteristic @ {characteristic.Uuid} found and accessed!");

                //check access to the characteristic
                Debug.Write("We have the following access to the characteristic: ");
                GattCharacteristicProperties properties = characteristic.CharacteristicProperties;
                foreach (GattCharacteristicProperties property in Enum.GetValues(typeof(GattCharacteristicProperties)))
                {
                    if (properties.HasFlag(property))
                    {
                        Debug.Write($"{property} ");
                    }
                }
                Debug.WriteLine("");

                //subscribe to the GATT characteristic's notification
                GattCommunicationStatus status = await characteristic.WriteClientCharacteristicConfigurationDescriptorAsync(
                    GattClientCharacteristicConfigurationDescriptorValue.Notify);
                if (status == GattCommunicationStatus.Success)
                {
                    Debug.WriteLine("Subscribing to the Indication/Notification");
                    characteristic.ValueChanged += DiceOrientationChangeHandler;
                }
                else
                {
                    Debug.WriteLine($"ERR1: {status}");
                }
            } else
            {
                Debug.WriteLine($"ERR2: {characteristicResult.Status}");
            }
        } else
        {
            Debug.WriteLine($"ERR3: {serviceResult.Status}");
        }

    }

    public void DiceOrientationChangeHandler(GattCharacteristic sender, GattValueChangedEventArgs eventArgs)
    {
        Debug.WriteLine($"Dice rolled...");
    }


    public void ConnectionStatusChangeHandler(BluetoothLEDevice bluetoothLEDevice, Object o)
    {
        Debug.WriteLine($"The device is now: {bluetoothLEDevice.ConnectionStatus}");
    }

输出如下：

找到了蓝牙LE设备[ee：ab：17：be：37：20]：已连接

找到并访问了服务@ c7e70010-c847-11e6-8175-8c89a55d403c！

找到并访问了@ c7e70012-c847-11e6-8175-8c89a55d403c特征！

我们可以通过以下方式访问该特征：无阅读指示

订阅指示/通知

设备现已：断开连接

但是，每当我更改设备的方向时，都不会发生任何事情。 服务uuid​​和特征uuid与我在Linux程序中使用的相同，方向更改处理程序正在其中工作。

片刻之后，最后一条消息将被打印到控制台：

线程0x2b40已退出，代码为0（0x0）。

订阅Bluetooth LE设备的通知时我做错了什么？

Answer 1

我终于找到了问题：

使用linux库，它将以某种方式自动确定GATT服务正在使用哪种通知类型。

使用Windows SDK，我必须通过使用GattClientCharacteristicConfigurationDescriptorValue.Indicate明确指定通知的类型是一种指示。

现在，一旦我“掷骰子”，便会触发该事件。