[Interest] QBluetoothServiceDiscoveryAgent cannot retrieve sdp uuids

[Jérôme Godbout]

> Minimal discovery only uses cached SDP values. If the platform does not
have any values the above message is the result. You have to do an active
scan/FullDiscovery.

How can we check if the device support the minimal discovery method? I just
get an empty result and a trace into the console. It's like it failed
silently to the application code and only leave a trace into the debug
console.

>  This is a problem. Please report a bug
As for the full discovery I end up with the following error popup on the
Android device from the system*:*
*"Unfortunately, Bluetooth Share has stopped."* with an ok button. After
that the whole blueooth is shutdown on the device!
it's the system Bluetooth stack that crash hard! The scan emit error
signal: PoweredOffError
Seem like if the device cannot be reach on the second scan it does crash
the bluetooth stack and bring the Android Bluetooth service along with it!

I have to quit the application and restart the Bluetooth stack and start
over and always get the same result with the complete scan!?!?

On 16 August 2018 at 01:51, Alex Blasche <alexander.blasche at qt.io> wrote:

>
>
> > -----Original Message-----
> > From: Interest <interest-bounces+alexander.blasche=qt.io at qt-project.org>
> On
> > Behalf Of Jérôme Godbout
> > Sent: Wednesday, 15 August 2018 21:55
> > To: Qt Interest <interest at qt-project.org>
> > Subject: [Interest] QBluetoothServiceDiscoveryAgent cannot retrieve sdp
> uuids
> >
> > Hi,
> > I'm trying to discover some particular Bluetooth device on Android, but
> I have
> > some trouble using the QBluetoothServiceDiscoveryAgent. Here's the
> workflow:
> >
> > 1.    Scan using QBluetoothDeviceDiscoveryAgent to discovers all devices.
> > 2.    Wait for scan to complete, wait for finished() signal.
> > 3.    Start a scan  QBluetoothServiceDiscoveryAgent for found devices
> one by
> > one. Using start(QBluetoothServiceDiscoveryAgent::MinimalDiscovery). I
> always
> > end up with the following error: cannot retrieve sdp uuids.
>
> Minimal discovery only uses cached SDP values. If the platform does not
> have any values the above message is the result. You have to do an active
> scan/FullDiscovery.
>
> > If I try the complete
> > discovery it just crash hard!
>
> This is a problem. Please report a bug (https://bugreports.qt.io) that
> included your Qt version, a stack trace and ideally a small test program
> that reproduces the problem for you.
>
> > I want to discover any device that can offer a particular services and I
> don't
> > controls device name nor the advertising of the BLE devices. Anyway to
> do this?
> > Or is it a bug with my Android device or am I using it improperly?
>
> If you are looking for BLE services they cannot be retrieved using the SDP
> (QBluetoothServiceDiscoveryAgent) unless the device choose to use a
> classic advertisement too. That's usually not the case though.
>
>
> > Do I have to use QLowEnergyControl and connect to each device one by one
> to
> > fetch the services list on Android to do this?
>
> Usually you should be able to identify the device using the device
> discovery already as the device discovery reveals quite a bit of
> information already. Otherwise yes, you actually have to connect.
>
> --
> Alex
> _______________________________________________
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> Interest at qt-project.org
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>
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