Need to be able to register for notification from characteristics that is only INDICATE

[CodeMusher]

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Steps to reproduce

1. Try to use a peripheral with a characteristic with only INDICATE

Expected behavior

Registration for updates should succeed

Actual behavior

Registration is not performed. The Windows implementation of the StartUpdatesNativeAsync only register in case of Notify.
It could be solved this way
GattWriteResult result;
if (NativeCharacteristic.CharacteristicProperties.HasFlag(GattCharacteristicProperties.Indicate))
result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Indicate);
else
result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Notify);

Crashlog

If something causes an exception paste full stack trace + Exception here

Configuration

Version of the Plugin: e.g. 1.0.0 / 1.0.1-alpha3
3.1.0-rc.1

Platform: e.g. iOS 10.1 / Android 4.4 / ... (including version!!! e.g. Android 5.1 / i0S 10)
UWP/Windows 10

Device: e.g. HTC Sensation /i Phone 7 ...

[smsissuechecker]

Hi @CodeMusher,

I'm the friendly issue checker.
Thanks for using the issue template 🌟
I appreciate it very much. I'm sure, the maintainers of this repository will answer, soon.

[janusw]

Actual behavior

Registration is not performed. The Windows implementation of the StartUpdatesNativeAsync only register in case of Notify. It could be solved this way GattWriteResult result; if (NativeCharacteristic.CharacteristicProperties.HasFlag(GattCharacteristicProperties.Indicate)) result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Indicate); else result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Notify);

This fix is supposed to go into Characteristic.StartUpdatesNativeAsync, right? It currently looks like this:

dotnet-bluetooth-le/Source/Plugin.BLE/Windows/Characteristic.cs

Lines 57 to 64 in 1e19fa8

	protected override async Task StartUpdatesNativeAsync(CancellationToken cancellationToken = default)
	{
	NativeCharacteristic.ValueChanged -= OnCharacteristicValueChanged;
	NativeCharacteristic.ValueChanged += OnCharacteristicValueChanged;
	var result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Notify);
	result.ThrowIfError();
	}

@CodeMusher Can you open a PR for it?

[AskBojesen]

I do not understand the issue. In our project we have a device with a lot of characteristics with only INDICATE.
and even one where the device decides if the characteristic should be send as NOTIFY or INDICATE.
And that works for iOS, Android and Windows

Remember:

• NOTIFY: Unacknowledged
• INDICATE: Acknowledged

[CodeMusher]

@janusw I can try. What is the correct procedure?

[AskBojesen]

But It could be related to how the device handle the requests.

I see the same in the current implementation for Windows, which is also what @janusw points out.
@CodeMusher : Should I make a PR you can test with the solution @janusw suggests?

var result = await NativeCharacteristic.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Notify);

[CodeMusher]

@AskBojesen Do you refer to my suggestion in the original issue?
That works for me but my peripheral has a characteristic with only INDICATE. I'm not sure what happens in case of both INDICATE and NOTIFY. Is one registration enough or do you need to register for both INDICATE and NOTIFY? I feel my knowledge ending here.

[AskBojesen]

I actually see now, that our device is lying in the characteristic properties - reporting NOTIFY, but it is indicate.

[CodeMusher]

Ok, so then you can understand my issue?

[AskBojesen]

Ok, so then you can understand my issue?

Yes I can imagine there could be an issue - I cannot reproduce.
I have created this PR: #858